Links Getting Started Administrators Application Developers Catalina Developers Jasper Developers | Security Manager HOW-TOBackground |
The Java SecurityManager is what allows a web browser
to run an applet in its own sandbox to prevent untrusted code from
accessing files on the local file system, connecting to a host other
than the one the applet was loaded from, and so on. In the same way
the SecurityManager protects you from an untrusted applet running in
your browser, use of a SecurityManager while running Tomcat can protect
your server from trojan servlets, JSPs, JSP beans, and tag libraries.
Or even inadvertent mistakes.
Imagine if someone who is authorized to publish JSPs on your site
inadvertently included the following in their JSP:
Every time this JSP was executed by Tomcat, Tomcat would exit.
Using the Java SecurityManager is just one more line of defense a
system administrator can use to keep the server secure and reliable.
WARNING - Implementation of a SecurityManager in
Tomcat has not been fully tested or had a security audit. Make sure that
you are satisfied with your SecurityManager configuration before allowing
untrusted users to publish web applications, JSPs, servlets, beans, or
tag libraries. However, running with a SecurityManager is definitely
better than running without one.
|
Permissions |
Permission classes are used to define what Permissions a class loaded
by Tomcat will have. There are a number of Permission classes that are
a standard part of the JDK, and you can create your own Permission class
for use in your own web applications. Both techniques are used in
Tomcat 4.
Standard Permissions |
This is just a short summary of the standard system SecurityManager
Permission classes applicable to Tomcat. See
http://java.sun.com/security/
for more information.
- java.util.PropertyPermission - Controls read/write
access to JVM properties such as
java.home .
- java.lang.RuntimePermission - Controls use of
some System/Runtime functions like
exit() and
exec() .
- java.io.FilePermission - Controls read/write/execute
access to files and directories.
- java.net.SocketPermission - Controls use of
network sockets.
- java.net.NetPermission - Controls use of
multicast network connections.
- java.lang.reflect.ReflectPermission - Controls
use of reflection to do class introspection.
- java.security.SecurityPermission - Controls access
to Security methods.
- java.security.AllPermission - Allows access to all
permissions, just as if you were running Tomcat without a
SecurityManager.
|
|
Configuring Tomcat With A SecurityManager |
Policy File Format
The security policies implemented by the Java SecurityManager are
configured in the $CATALINA_HOME/conf/catalina.policy file.
This file completely replaces the java.policy file present
in your JDK system directories. The catalina.policy file
can be edited by hand, or you can use the
policytool
application that comes with Java 1.2 or later.
Entries in the catalina.policy file use the standard
java.policy file format, as follows:
, Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) |
// Example policy file entry
grant [signedBy <signer>,] [codeBase <code source>] {
permission <class> [<name> [, <action list>]];
};
| , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) |
The signedBy and codeBase entries are
optional when granting permissions. Comment lines begin with "//" and
end at the end of the current line. The codeBase is in the
form of a URL, and for a file URL can use the ${java.home}
and ${catalina.home} properties (which are expanded out to
the directory paths defined for them by the JAVA_HOME and
CATALINA_HOME environment variables).
The Default Policy File
The default $CATALINA_HOME/conf/catalina.policy file
looks like this:
, Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) |
// ============================================================================
// catalina.corepolicy - Security Policy Permissions for Tomcat 4.0
//
// This file contains a default set of security policies to be enforced (by the
// JVM) when Catalina is executed with the "-security" option. In addition
// to the permissions granted here, the following additional permissions are
// granted to the codebase specific to each web application:
//
// * Read access to the document root directory
//
// $Id: security-manager-howto.xml,v 1.1 2001/09/09 22:43:48 craigmcc Exp $
// ============================================================================
// ========== SYSTEM CODE PERMISSIONS =========================================
// These permissions apply to javac
grant codeBase "file:${java.home}/lib/-" {
permission java.security.AllPermission;
};
// These permissions apply to all shared system extensions
grant codeBase "file:${java.home}/jre/lib/ext/-" {
permission java.security.AllPermission;
};
// These permissions apply to javac when ${java.home] points at $JAVA_HOME/jre
grant codeBase "file:${java.home}/../lib/-" {
permission java.security.AllPermission;
};
// These permissions apply to all shared system extensions when
// ${java.home} points at $JAVA_HOME/jre
grant codeBase "file:${java.home}/lib/ext/-" {
permission java.security.AllPermission;
};
// ========== CATALINA CODE PERMISSIONS =======================================
// These permissions apply to the server startup code
grant codeBase "file:${catalina.home}/bin/bootstrap.jar" {
permission java.security.AllPermission;
};
// These permissions apply to the servlet API classes
// and those that are shared across all class loaders
// located in the "common" directory
grant codeBase "file:${catalina.home}/common/-" {
permission java.security.AllPermission;
};
// These permissions apply to the container's core code, plus any additional
// libraries installed in the "server" directory
grant codeBase "file:${catalina.home}/server/-" {
permission java.security.AllPermission;
};
// These permissions apply to the jasper page compiler
// located in the "jasper" directory.
grant codeBase "file:${catalina.home}/jasper/-" {
permission java.security.AllPermission;
};
// These permissions apply to shared web application libraries
// including the Jasper runtime library installed in the "lib" directory
grant codeBase "file:${catalina.home}/lib/-" {
permission java.security.AllPermission;
};
// These permissions apply to shared web application classes
// located in the "classes" directory
grant codeBase "file:${catalina.home}/classes/-" {
permission java.security.AllPermission;
};
// ========== WEB APPLICATION PERMISSIONS =====================================
// These permissions are granted by default to all web applications
// In addition, a web application will be given a read FilePermission
// and JndiPermission for all files and directories in its document root.
grant {
// Required for JNDI lookup of named JDBC DataSource's and
// javamail named MimePart DataSource used to send mail
permission java.util.PropertyPermission "java.home", "read";
permission java.util.PropertyPermission "java.naming.*", "read";
permission java.util.PropertyPermission "javax.sql.*", "read";
// OS Specific properties to allow read access
permission java.util.PropertyPermission "os.name", "read";
permission java.util.PropertyPermission "os.version", "read";
permission java.util.PropertyPermission "os.arch", "read";
permission java.util.PropertyPermission "file.separator", "read";
permission java.util.PropertyPermission "path.separator", "read";
permission java.util.PropertyPermission "line.separator", "read";
// JVM properties to allow read access
permission java.util.PropertyPermission "java.version", "read";
permission java.util.PropertyPermission "java.vendor", "read";
permission java.util.PropertyPermission "java.vendor.url", "read";
permission java.util.PropertyPermission "java.class.version", "read";
permission java.util.PropertyPermission "java.specification.version", "read";
permission java.util.PropertyPermission "java.specification.vendor", "read";
permission java.util.PropertyPermission "java.specification.name", "read";
permission java.util.PropertyPermission "java.vm.specification.version", "read";
permission java.util.PropertyPermission "java.vm.specification.vendor", "read";
permission java.util.PropertyPermission "java.vm.specification.name", "read";
permission java.util.PropertyPermission "java.vm.version", "read";
permission java.util.PropertyPermission "java.vm.vendor", "read";
permission java.util.PropertyPermission "java.vm.name", "read";
// Required for getting BeanInfo
permission java.lang.RuntimePermission "accessClassInPackage.sun.beans.*";
// Allow read of JAXP compliant XML parser debug
permission java.util.PropertyPermission "jaxp.debug", "read";
};
// You can assign additional permissions to particular web applications by
// adding additional "grant" entries here, based on the code base for that
// application, /WEB-INF/classes/, or /WEB-INF/lib/ jar files.
//
// Different permissions can be granted to JSP pages, classes loaded from
// the /WEB-INF/classes/ directory, all jar files in the /WEB-INF/lib/
// directory, or even to individual jar files in the /WEB-INF/lib/ directory.
//
// For instance, assume that the standard "examples" application
// included a JDBC driver that needed to establish a network connection to the
// corresponding database and used the scrape taglib to get the weather from
// the NOAA web server. You might create a "grant" entries like this:
//
// The permissions granted to the context root directory apply to JSP pages.
// grant codeBase "file:${catalina.home}/webapps/examples/-" {
// permission java.net.SocketPermission "dbhost.mycompany.com:5432", "connect";
// permission java.net.SocketPermission "*.noaa.gov:80", "connect";
// };
//
// The permissions granted to the context WEB-INF/classes directory
// grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/classes/-" {
// };
//
// The permission granted to your JDBC driver
// grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/lib/driver.jar!/-" {
// permission java.net.SocketPermission "dbhost.mycompany.com:5432", "connect";
// };
// The permission granted to the scrape taglib
// grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/lib/scrape.jar!/-" {
// permission java.net.SocketPermission "*.noaa.gov:80", "connect";
// };
| , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) |
Starting Tomcat With A SecurityManager
Once you have configured the catalina.policy file for use
with a SecurityManager, Tomcat can be started with a SecurityManager in
place by using the "-security" option:
, Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) |
$CATALINA_HOME/bin/catalina.sh start -security (Unix)
%CATALINA_HOME%\bin\catalina start -security (Windows)
| , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
/images/void.gif) | , Section 12. For a more introductory level
document for web application developers as well as administrators, see
(FIXME - link to backgrounder on container managed security
to be provided).
For information about utilizing the Single Sign On feature of
Tomcat 4 (allowing a user to authenticate themselves once across the entire
set of web applications associated with a virtual host), see
here.
A Realm is a "database" of usernames and passwords that
identify valid users of a web application (or set of web applications), plus
an enumeration of the list of roles associated with each valid user.
You can think of roles as similar to groups in Unix-like operating
systems, because access to specific web application resources is granted to
all users possessing a particular role (rather than enumerating the list of
associated usernames). A particular user can have any number of roles
associated with their username.
Although the Servlet Specification describes a portable mechanism for
applications to declare their security requirements (in the
web.xml deployment descriptor), there is no portable API
defining the interface between a servlet container and the associated user
and role information. In many cases, however, it is desireable to "connect"
a servlet container to some existing authentication database or mechanism
that already exists in the production environment. Therefore, Tomcat 4
defines a Java interface (org.apache.catalina.Realm) that
can be implemented by "plug in" components to establish this connection.
Three standard plug-ins are provided, supporting connection to three different
sources of authentication information:
JDBCRealm - Accesses authentication information
stored in a relational database, accessed via a JDBC driver.
JNDIRealm - Accesses authentication information
stored in an LDAP based directory server, accessed via a JNDI provider.
MemoryRealm - Accesses authentication
information stored in an in-memory object collection, which is initialized
from an XML document (conf/tomcat-users.xml).
It is also possible to write your own Realm implementation,
and integrate it with Tomcat 4. However, doing this is beyond the scope of
this document. See (FIXME - reference to developer stuff)
for more information.
Before getting into the details of the standard Realm implementations, it is
important to understand, in general terms, how a Realm is configured. In
general, you will be adding an XML element to your conf/server.xml
configuration file, that looks something like this:
<Realm className="... class name for this implementation"
... other attributes for this implementation .../>
The <Realm> element can be nested inside one of three
different elements, which has a direct impact on the "scope" of that Realm
(i.e. which web applications will share the same authentication information):
Inside an <Engine> element - This Realm will be shared
across ALL web applications on ALL virtual hosts, UNLESS it is overridden
by a Realm element nested inside a subordinate <Host>
or <Context> element.
Inside a <Host> element - This Realm will be shared across
ALL web applications for THIS virtual host, UNLESS it is overridden
by a Realm element nested inside a subordinate <Context>
element.
Inside a <Context> element - This Realm will be used ONLY
for THIS web application.
Introduction
JDBCRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a relational database
accessed via a JDBC driver. There is substantial configuration flexibility
that lets you adapt to existing table and column names, as long as your
database structure conforms to the following requirements:
There must be a table, referenced below as the users table,
that contains one row for every valid user that this Realm
should recognize.
The users table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat when the user logs in.
Password to be recognized by Tomcat when the user logs in.
This value may in cleartext or digested - see below for more
information.
There must be a table, referenced below as the user roles table,
that contains one row for every valid role that is assigned to a
particular user. It is legal for a user to have zero, one, or more than
one valid role.
The user roles table must contain at least two columns (it may
contain more if your existing applications required it):
Username to be recognized by Tomcat (same value as is specified
in the users table).
Role name of a valid role associated with this user.
Quick Start
To set up Tomcat to use JDBCRealm, you will need to follow these steps:
If you have not yet done so, create tables and columns in your database
that conform to the requirements described above.
Configure a database username and password for use by Tomcat, that has
at least read only access to the tables described above. (Tomcat will
never attempt to write to these tables.)
Place a copy of the JDBC driver you will be using inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Note that only JAR files are recognized!
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JDBCRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The database username used to establish a JDBC connection.
The database password used to establish a JDBC connection.
The database URL used to establish a JDBC connection.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The fully qualified Java class name of the JDBC driver to be used.
Consult the documentation for your JDBC driver for the appropriate
value.
The name of the column, in the user roles table, that
contains the name of a role assigned to this user.
The name of the column, in the users table, that contains
the password for this user (either in clear text, or digested if the
digest attribute is set).
The name of the column, in the users and user roles
tables, that contains the username of this user.
The name of the table that contains one row for each role
assigned to a particular username. This table must include at
least the columns named by the userNameCol and
roleNameCol attributes.
The name of the table that contains one row for each username
to be recognized by Tomcat. This table must include at least the columns
named by the userNameCol and userCredCol
attributes.
Example
An example SQL script to create the needed tables might look something
like this (adapt the syntax as required for your particular database):
create table users (
user_name varchar(15) not null primary key,
user_pass varchar(15) not null
);
create table user_roles (
user_name varchar(15) not null,
role_name varchar(15) not null,
primary key (user_name, role_name)
);
Example Realm elements are included (commented out) in the
default $CATALINA_HOME/conf/server.xml file. Here's an example
for using a MySQL database called "authority", configured with the tables
described above, and accessed with username "dbuser" and password "dbpass":
<Realm className="org.apache.catalina.realm.JDBCRealm" debug="99"
driverName="org.gjt.mm.mysql.Driver"
connectionURL="jdbc:mysql://localhost/authority?user=dbuser;password=dbpass"
userTable="users" userNameCol="user_name" userCredCol="user_pass"
userRoleTable="user_roles" roleNameCol="role_name"/>
Additional Notes
JDBCRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the users and user roles
table is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
JNDIRealm is an implementation of the Tomcat 4
Realm interface that looks up users in a directory server
accessed by a JNDI provider (typically, the standard LDAP provider that
is available with the JNDI API classes). There is substantial configuration
flexibility that lets you adapt to the existing schema inside your directory
server, as long as it conforms to the following requirements:
Each user that can be authenticated is represented by an individual
element in the top level DirContext that is accessed
via the connectionURL attribute.
The user element must have the following characteristics:
The distinguished name (dn) attribute of this element
contains the username that is presented for authentication.
There must be an attribute (identified by the userPassword
attribute of our Realm element) that contains the user's
password, either in clear text or digested (see below for more info).
Each group of users that has been assigned a particular role is
represented by an individual element in the top level
DirContext that is accessed via the
connectionURL attribute.
The user group element must have the following characteristics:
The set of all possible groups of interest can be selected by an LDAP
search pattern configured by the roleSearch attribute
of our Realm element.
The roleSearch pattern optionally includes pattern
replacements "{0}" for the distinguished name, and/or "{1} for the
username, of the authenticated user for which roles will be
retrieved.
The roleBase attribute can be set to the element that
is the base of the search for matching roles. If not specified,
the entire directory context will be searched.
The roleSubtree attribute can be set to true
if you wish to search the entire subtree of the directory context.
The default value of false requests a search of only the
current level.
The element includes an attribute (whose name is configured by the
roleName attribute of our Realm element)
containing the name of the role represented by this element.
There must be an administrator username and password that Tomcat can
use to establish a connection to the directory server, with at least
read-only access to the information described above. A future
version of Tomcat will support an option to use the user's username and
password to attempt this connection.
Quick Start
To set up Tomcat to use JNDIRealm, you will need to follow these steps:
Make sure your directory server is configured with a schema that matches
the requirements listed above.
Configure a username and password for use by Tomcat, that has
at least read only access to the information described above. (Tomcat will
never attempt to modify this information.)
Place a copy of the JNDI driver you will be using (typically
ldap.jar available with JNDI) inside the
$CATALINA_HOME/server/lib directory (if you do not need it
visible to web applications) or $CATALINA_HOME/common/lib
(if it will be used both by Tomcat 4 and by your apps).
Set up a <Realm> element, as described below, in your
$CATALINA_HOME/conf/server.xml file.
Restart Tomcat 4 if it is already running.
Realm Element Attributes
To configure JNDIRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.JDBCRealm" here.
The directory server username used to establish a JNDI connection.
The directory server password used to establish a JNDI connection.
The directory server URL used to establish a JNDI connection.
The fully qualified Java class name of the JNDI context factory to be
used for this connection. By default, the standard JNDI LDAP provider
is used (com.sun.jndi.ldap.LdapCtxFactory).
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
The base element for role searches. If not specified, the top level
element in the directory context will be used.
The name of the directory server attribute containing the role name.
An LDAP search pattern for selecting roles in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want roles for, and/or {1} to substitute in the username of
the user you want roles for.
Set to true if you want role searches to search subtrees
of the element selected by roleBase. The default value of
false causes only the top level element to be searched.
The name of the directory server attribute (in the user element) that
contains the cleartext or digested user password (depending on the setting
of the digest attribute).
An LDAP search pattern for selecting users in this Realm, following the
syntax supported by the java.text.MessageFormat class. Use
{0} to substitute in the distinguished name of the user you
want to select.
Example
Creation of the appropriate schema in your directory server is beyond the
scope of this document, because it is unique to each directory server
implementation. In the examples below, we will assume that you are using a
distribution of the OpenLDAP directory server (version 2.0.11 or later), which
can be downloaded from
http://www.openldap.org. Assume that
your slapd.conf file contains the following settings
(among others):
database ldbm
suffix dc="mycompany",dc="com"
rootdn "cn=Manager,dc=mycompany,dc=com"
rootpw secret
These settings help us identify values for the values to be specified for
connectionName, and connectionPassword, and we
will assume for connectionURL that the directory server runs on
the same machine as Tomcat. See
http://java.sun.com/products/jndi/docs.html
for more information about configuring and using the JNDI LDAP provider.
Next, assume that this directory server has been populated with elements
as shown below (in LDIF format), which define the same users and roles
as the default $CATALINA_HOME/conf/tomcat-users.xml does for
MemoryRealm:
# Define a user named 'tomcat'
dn: cn=tomcat,dc=mycompany,dc=com
cn: tomcat
userPassword: tomcat
sn: Tomcat User
objectClass: person
# Define a user named 'role1'
dn: cn=role1,dc=mycompany,dc=com
cn: role1
userPassword: tomcat
sn: Role1 User
objectClass: person
# Define a user named 'both'
dn: cn=both,dc=mycompany,dc=com
cn: both
userPassword: tomcat
sn: Both User
objectClass: person
# Define an entry to base role searches on
dn: dc=roles,dc=mycompany,dc=com
cn: roles
objectClass: person
sn: Roles Entry
# Define all members of the 'tomcat' role
dn: cn=tomcat,dc=roles,dc=mycompany,dc=com
cn: tomcat
objectClass: groupOfUniqueNames
uniqueMember: cn=tomcat,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
# Define all members of the 'role1' role
dn: cn=role1,dc=roles,dc=mycompany,dc=com
cn: role1
objectClass: groupOfUniqueNames
uniqueMember: cn=role1,dc=mycompany,dc=com
uniqueMember: cn=both,dc=mycompany,dc=com
An example Realm element for the OpenLDAP directory server
configured as described above might look like this:
<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"
connectionName="cn=Manager,dc=mycompany,dc=com"
connectionPassword="secret"
connectionURL="ldap://localhost:389"
roleBase="dc=roles,dc=mcclan,dc=net"
roleName="cn"
roleSearch="(uniqueMember={0})"
roleSubtree="false"
userPassword="userPassword"
userPattern="cn={0},dc=mycompany,dc=com"
/>
Additional Notes
JNDIRealm operates according to the following rules:
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm. Thus, any changes you have made to the database
directly (new users, changed passwords or roles, etc.) will be immediately
reflected.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser). Any changes to the database information for an
already authenticated user will not be reflected until
the next time that user logs on again.
Administering the information in the directory server
is the responsibility of your own applications. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
Introduction
MemoryRealm is a simple demonstration implementation of the
Tomcat 4 Realm interface. It is not designed for production use.
At startup time, MemoryRealm loads information about all users, and their
corresponding roles, from an XML document (by default, this document is loaded from $CATALINA_HOME/conf/tomcat-users.xml). Changes to the data
in this file are not recognized until Tomcat is restarted.
Realm Element Attributes
To configure MemoryRealm, you will create a <Realm>
element and nest it in your $CATALINA_HOME/conf/server.xml file,
as described above. The following
attributes are supported by this implementation:
The fully qualified Java class name of this Realm implementation.
You MUST specify the value
"org.apache.catalina.realm.MemoryRealm" here.
The level of debugging detail logged by this Realm
to the associated Logger. Higher numbers
generate more detailed output. If not specified, the default
debugging detail level is zero (0).
The digest algorithm used to store passwords in non-plaintext formats.
Valid values are those accepted for the algorithm name by the
java.security.MessageDigest class. See
Digested Passwords for more
information. If not specified, passwords are stored in clear text.
Absolute or relative (to $CATALINA_HOME) pathname of the XML document
containing our valid usernames, passwords, and roles. See below for more
information on the format of this file. If not specified, the value
conf/tomcat-users.xml is used.
User File Format
The users file (by default, conf/tomcat-users.xml must be an
XML document, with a root element <tomcat-users>. Nested
inside the root element will be a <user> element for each
valid user, consisting of the following attributes:
name - Username this user must log on with.
password - Password this user must log on with (in
clear text if the digest attribute was not set on the
<Realm> element, or digested appropriately as
described here otherwise).
roles - Comma-delimited list of the role names
associated with this user.
Example
The default installation of Tomcat 4 is configured with a MemoryRealm
nested inside the <Engine> element, so that it applies
to all virtual hosts and web applications. The default contents of the
conf/tomcat-users.xml file is:
<tomcat-users>
<user name="tomcat" password="tomcat" roles="tomcat" />
<user name="role1" password="tomcat" roles="role1" />
<user name="both" password="tomcat" roles="tomcat,role1" />
</tomcat-users>
Additional Notes
MemoryRealm operates according to the following rules:
When Tomcat first starts up, it loads all defined users and their
associated information from the users file. Changes to the data in
this file will not be recognized until Tomcat is
restarted.
When a user attempts to access a protected resource for the first time,
Tomcat 4 will call the authenticate() method of this
Realm.
Once a user has been authenticated, the user (and his or her associated
roles) are cached within Tomcat for the duration of the user's login.
(For FORM-based authentication, that means until the session times out or
is invalidated; for BASIC authentication, that means until the user
closes their browser).
Administering the information in the users file is the responsibility
of your application. Tomcat does not
provide any built-in capabilities to maintain users and roles.
Debugging and exception messages logged by this Realm will
be recorded by the Logger that is associated with our
surrounding Context, Host, or
Engine. By default, the corresponding Logger will create a
log file in the $CATALINA_HOME/logs directory.
For each of the standard Realm implementations, the user's
password (by default) is stored in clear text. In many environments, this is
undesireable because casual observers of the authentication data can collect
enough information to log on successfully, and impersonate other users.
To avoid this problem, the standard implementations support the concept of
digesting user passwords. This causes the stored version of the
passwords to be encoded (in a form that is not easily reversible), but that
the Realm implementation can still utilize for authentication.
Digested passwords are selected by specifying the digest
attribute on your <Realm> element. The value for this
attribute must be one of the digest algorithms supported by the
java.security.MessageDigest class (SHA, MD2, or MD5). When you
select this option, the contents of the password that is stored in the
Realm must be the cleartext version of the password, as digested
by the specified algorithm.
When the authenticate() method of the Realm is called, the
(cleartext) password specified by the user is itself digested by the same
algorithm, and the result is compared with the value returned by the
Realm. An equal match implies that the cleartext version of the
original password is the same as the one presented by the user, so that this
user should be authorized.
To calculate the digested value of a cleartext password, two convenience
techniques are supported:
If you are writing an application that needs to calculate digested
passowrds dynamically, call the static Digest() method of the
org.apache.catalina.realm.RealmBase class, passing the
cleartext password and the digest algorithm name as arguments. This
method will return the digested password.
If you want to execute a command line utility to calculate the digested
password, simply execute
java org.apache.catalina.realm.RealmBase \
-a {algorithm} {cleartext-password}
and the digested version of this cleartext password will be returned to
standard output.
To use either of the above techniques, the
$CATALINA_HOME/server/lib/catalina.jar file will need to be
on your class path to make the RealmBase class available.
The example application shipped with Tomcat 4 includes an area that is
protected by a security constraint, utilizing form-based login. To access it,
point your browser at
http://localhost:8080/examples/jsp/security/protected/
and log on with one of the usernames and passwords described for the default
MemoryRealm.
If you wish to use the Manager Application
to deploy and undeploy applications in a running Tomcat 4 installation, you
MUST add the "manager" role to at least one username in your selected Realm
implementation. This is because the manager web application itself uses a
security constraint that requires role "manager" to access ANY request URI
within that application.
For security reasons, no username in the default Realm (i.e. using
conf/tomcat-users.xml is assigned the "manager" role. Therfore,
no one will be able to utilize the features of this application until the
Tomcat administrator specifically assigns this role to one or more users.
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