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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
]>
<document url="realm.html">

  &project;

  <properties>
    <author email="craigmcc@apache.org">Craig R. McClanahan</author>
    <title>The Realm Component</title>
  </properties>

<body>

<section name="Table of Contents">
<toc/>
</section>

<section name="Introduction">

  <p>A <strong>Realm</strong> element represents a "database" of usernames,
  passwords, and <em>roles</em> (similar to Unix <em>groups</em>) assigned
  to those users.  Different implementations of Realm allow Catalina to be
  integrated into environments where such authentication information is already
  being created and maintained, and then utilize that information to implement
  <em>Container Managed Security</em> as described in the Servlet
  Specification.</p>

  <p>A Catalina container (<a href="engine.html">Engine</a>,
  <a href="host.html">Host</a>, or <a href="context.html">Context</a>) may
  contain no more than one Realm element (although if supported by the Realm
  this one Realm may itself contain multiple nested Realms). In addition, the
  Realm associated with an Engine or a Host is automatically inherited by
  lower-level containers unless the lower level container explicitly defines its
  own Realm. If no Realm is configured for the Engine, an instance of the
  <a href="#Null_Realm_-_org.apache.catalina.realm.NullRealm">Null Realm</a>
  will be configured for the Engine automatically.</p>

  <p>For more in-depth information about container managed security in web
  applications, as well as more information on configuring and using the
  standard realm component implementations, please see the
  <a href="../realm-howto.html">Container-Managed Security Guide</a>.
  </p>

    <p><em>The description below uses the variable name $CATALINA_BASE to refer the
    base directory against which most relative paths are resolved. If you have
    not configured Tomcat for multiple instances by setting a CATALINA_BASE
    directory, then $CATALINA_BASE will be set to the value of $CATALINA_HOME,
    the directory into which you have installed Tomcat.</em></p>

</section>


<section name="Attributes">

  <subsection name="Common Attributes">

    <p>All implementations of <strong>Realm</strong>
    support the following attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This class must
        implement the <code>org.apache.catalina.Realm</code> interface.</p>
      </attribute>

    </attributes>

    <p>Unlike most Catalina components, there are several standard
    <strong>Realm</strong> implementations available.  As a result,
    the <code>className</code> attribute MUST be used to select the
    implementation you wish to use.</p>

  </subsection>


  <subsection name="DataSource Database Realm - org.apache.catalina.realm.DataSourceRealm">

    <p>The <strong>DataSource Database Realm</strong> connects Tomcat to
    a relational database, accessed through a JNDI named JDBC DataSource
    to perform lookups of usernames, passwords, and their associated
    roles.  Because the lookup is done each time that it is required,
    changes to the database will be immediately reflected in the
    information used to authenticate new logins.</p>

    <p>The JDBC Realm uses a single db connection. This requires that
    realm based authentication be synchronized, i.e. only one authentication
    can be done at a time. This could be a bottleneck for applications
    with high volumes of realm based authentications.</p>

    <p>The DataSource Database Realm supports simultaneous realm based
    authentications and allows the underlying JDBC DataSource to
    handle optimizations like database connection pooling.</p>

    <p>A rich set of additional attributes lets you configure the name
    of the JNDI JDBC DataSource, as well as the table and
    column names used to retrieve the required information:</p>

    <attributes>

      <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
        <p>When this attribute has the value of <code>authOnly</code> or
        <code>strictAuthOnly</code>, the <strong>roleNameCol</strong> and
        <strong>userRoleTable</strong> attributes become optional. If those two
        attributes are omitted, the user's roles will not be loaded by this
        Realm.</p>
      </attribute>

      <attribute name="dataSourceName" required="true">
        <p>The name of the JNDI JDBC DataSource for this Realm.</p>
      </attribute>

      <attribute name="localDataSource" required="false">
        <p>When the realm is nested inside a Context element, this allows the
        realm to use a DataSource defined for the Context rather than a global
        DataSource.  If not specified, the default is <code>false</code>: use a
        global DataSource.</p>
      </attribute>

      <attribute name="roleNameCol" required="false">
        <p>Name of the column, in the "user roles" table, which contains
        a role name assigned to the corresponding user.</p>
        <p>This attribute is <strong>required</strong> in majority of
        configurations. See <strong>allRolesMode</strong> attribute for
        a rare case when it can be omitted.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

      <attribute name="stripRealmForGss" required="false">
        <p>When processing users authenticated via the GSS-API, this attribute
        controls if any &quot;@...&quot; is removed from the end of the user
        name. If not specified, the default is <code>true</code>.</p>
      </attribute>

      <attribute name="userCredCol" required="true">
        <p>Name of the column, in the "users" table, which contains
        the user's credentials (i.e. password).  If a
        <code>CredentialHandler</code> is specified, this component
        will assume that the passwords have been encoded with the
        specified algorithm.  Otherwise, they will be assumed to be
        in clear text.</p>
      </attribute>

      <attribute name="userNameCol" required="true">
        <p>Name of the column, in the "users" and "user roles" table,
        that contains the user's username.</p>
      </attribute>

      <attribute name="userRoleTable" required="false">
        <p>Name of the "user roles" table, which must contain columns
        named by the <code>userNameCol</code> and <code>roleNameCol</code>
        attributes.</p>
        <p>This attribute is <strong>required</strong> in majority of
        configurations. See <strong>allRolesMode</strong> attribute for
        a rare case when it can be omitted.</p>
      </attribute>

      <attribute name="userTable" required="true">
        <p>Name of the "users" table, which must contain columns named
        by the <code>userNameCol</code> and <code>userCredCol</code>
        attributes.</p>
      </attribute>

      <attribute name="X509UsernameRetrieverClassName" required="false">
        <p>When using X509 client certificates, this specifies the class name
        that will be used to retrieve the user name from the certificate.
        The class must implement the
        <code>org.apache.catalina.realm.X509UsernameRetriever</code>
        interface. The default is to use the certificate's SubjectDN
        as the username.</p>
      </attribute>
    </attributes>

    <p>See the <a href="../realm-howto.html#DataSourceRealm">
    DataSource Realm How-To</a> for more information on setting up container
    managed security using the DataSource Database Realm component.</p>

  </subsection>


  <subsection name="JNDI Directory Realm - org.apache.catalina.realm.JNDIRealm">

    <p>The <strong>JNDI Directory Realm</strong> connects Tomcat to
    an LDAP Directory, accessed through an appropriate JNDI driver,
    that stores usernames, passwords, and their associated
    roles. Changes to the directory are immediately reflected in the
    information used to authenticate new logins.</p>

    <p>The directory realm supports a variety of approaches to using
    LDAP for authentication:</p>

    <ul>
    <li>The realm can either use a pattern to determine the
    distinguished name (DN) of the user's directory entry, or search
    the directory to locate that entry.
    </li>

    <li>The realm can authenticate the user either by binding to the
    directory with the DN of the user's entry and the password
    presented by the user, or by retrieving the password from the
    user's entry and performing a comparison locally.
    </li>

    <li>Roles may be represented in the directory as explicit entries
    found by a directory search (e.g. group entries of which the user
    is a member), as the values of an attribute in the user's entry,
    or both.
    </li>
    </ul>

    <p> A rich set of additional attributes lets you configure the
    required behaviour as well as the connection to the underlying
    directory and the element and attribute names used to retrieve
    information from the directory:</p>

    <attributes>

      <attribute name="adCompat" required="false">
        <p>Microsoft Active Directory often returns referrals.
        When iterating over NamingEnumerations these lead to
        PartialResultExceptions. If you want us to ignore those exceptions,
        set this attribute to "true". Unfortunately there's no stable way
        to detect, if the Exceptions really come from an AD referral.
        The default value is "false".</p>
      </attribute>

      <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
      </attribute>

      <attribute name="alternateURL" required="false">
        <p>If a socket connection cannot be made to the provider at
        the <code>connectionURL</code> an attempt will be made to use the
        <code>alternateURL</code>.</p>
      </attribute>

      <attribute name="authentication" required="false">
        <p>A string specifying the type of authentication to use.
        "none", "simple", "strong" or a provider specific definition
        can be used. If no value is given the providers default is used.</p>
      </attribute>

      <attribute name="cipherSuites" required="false">
        <p>Specify which cipher suites are allowed when trying to open
        a secured connection using StartTLS. The allowed cipher suites
        are specified by a comma separated list. The default is to use the
        cipher suites of the JVM.</p>
      </attribute>

      <attribute name="commonRole" required="false">
        <p>A role name assigned to each successfully authenticated user in
        addition to the roles retrieved from LDAP. If not specified, only
        the roles retrieved via LDAP are used.</p>
      </attribute>

      <attribute name="connectionName" required="false">
        <p>The directory username to use when establishing a
        connection to the directory for LDAP search operations. If not
        specified an anonymous connection is made, which is often
        sufficient unless you specify the <code>userPassword</code>
        property.</p>
      </attribute>

      <attribute name="connectionPassword" required="false">
        <p>The directory password to use when establishing a
        connection to the directory for LDAP search operations. If not
        specified an anonymous connection is made, which is often
        sufficient unless you specify the <code>userPassword</code>
        property.</p>
      </attribute>

      <attribute name="connectionPoolSize" required="false">
        <p>The JNDI realm can use a pool of connections to the directory server
        to avoid blocking on a single connection. This attribute value is the
        maximum pool size. If not specified, it will use <code>1</code>, which
        means a single connection will be used.</p>
      </attribute>

      <attribute name="connectionTimeout" required="false">
        <p>The timeout in milliseconds to use when establishing the connection
        to the LDAP directory. If not specified, a value of 5000 (5 seconds) is
        used.</p>
      </attribute>

      <attribute name="connectionURL" required="true">
        <p>The connection URL to be passed to the JNDI driver when
        establishing a connection to the directory.</p>
      </attribute>

      <attribute name="contextFactory" required="false">
        <p>Fully qualified Java class name of the factory class used
        to acquire our JNDI <code>InitialContext</code>.  By default,
        assumes that the standard JNDI LDAP provider will be utilized.</p>
      </attribute>

      <attribute name="derefAliases" required="false">
        <p>A string specifying how aliases are to be dereferenced during
        search operations. The allowed values are "always", "never",
        "finding" and "searching". If not specified, "always" is used.</p>
      </attribute>

      <attribute name="forceDnHexEscape" required="false">
        <p>A setting of <code>true</code> forces escaping in the String
        representation of a distinguished name to use the <code>\nn</code> form.
        This may avoid issues with realms using Active Directory which appears
        to be more tolerant of optional escaping when the <code>\nn</code> form
        is used. If not specified, the default of <code>false</code> will be
        used.</p>
      </attribute>

      <attribute name="hostnameVerifierClassName" required="false">
        <p>The name of the class to use for hostname verification when
        using StartTLS for securing the connection to the ldap server.
        The default constructor will be used to construct an instance of
        the verifier class. The default is to accept only those hostnames,
        that are valid according to the peer certificate of the ldap
        server.</p>
      </attribute>

      <attribute name="protocol" required="false">
         <p>A string specifying the security protocol to use. If not given
         the providers default is used.</p>
      </attribute>

      <attribute name="readTimeout" required="false">
          <p>The timeout, in milliseconds, to use when trying to read from a
          connection to the directory. If not specified, the default of 5000
          (5 seconds) is used.</p>
      </attribute>

      <attribute name="referrals" required="false">
        <p>How do we handle JNDI referrals? Allowed values are
        "ignore", "follow", or "throw"  (see javax.naming.Context.REFERRAL
        for more information).
        Microsoft Active Directory often returns referrals.
        If you need to follow them set referrals to "follow".
        Caution: if your DNS is not part of AD, the LDAP client lib might try
        to resolve your domain name in DNS to find another LDAP server.</p>
      </attribute>

      <attribute name="roleBase" required="false">
        <p>The base directory entry for performing role searches. If not
        specified the top-level element in the directory context will be used.
        If specified it may optionally include pattern replacements
        &quot;{0}&quot;..&quot;{n}&quot; corresponding to the name parts of the
        user's distinguished name (as returned by
        <code>javax.naming.Name.get()</code>).</p>
      </attribute>

      <attribute name="roleName" required="false">
        <p>The name of the attribute that contains role names in the
        directory entries found by a role search. In addition you can
        use the <code>userRoleName</code> property to specify the name
        of an attribute, in the user's entry, containing additional
        role names.</p>
        <p>If <code>roleName</code> is not specified a role
        search does not take place, and roles are taken only from the
        user's entry.</p>
      </attribute>

      <attribute name="roleNested" required="false">
        <p>Set to <code>true</code> if you want to nest roles into roles.
        When a role search is performed and the value of this property is
        <code>true</code>, the search will be repeated recursively to find
        all the roles that belong to the user either directly or indirectly.
        If not specified, the default value of <code>false</code> is used.</p>
      </attribute>

      <attribute name="roleSearch" required="false">
        <p>The LDAP filter expression used for performing role
        searches.</p>

        <p>Use <code>{0}</code> to substitute the distinguished name (DN)
        of the user, and/or <code>{1}</code> to substitute the username,
        and/or <code>{2}</code> for the value of an attribute from the
        user's directory entry, of the authenticated user.
        The name of the attribute that provides the value for <code>{2}</code>
        is configured by the <code>userRoleAttribute</code> property.</p>

        <p>When <code>roleNested</code> property is <code>true</code>,
        this filter expression will be also used to recursively search for
        other roles, which indirectly belong to this user. To find the
        roles that match the newly found role, the following values
        are used:
        <code>{0}</code> is substituted by the distinguished name of the newly
        found role, and both <code>{1}</code> and <code>{2}</code> are
        substituted by the name of the role (see the <code>roleName</code>
        property). The <code>userRoleAttribute</code> property is not
        applicable to this search.</p>

        <p>If this property is not specified, a role search does not take
        place and roles are taken only from the attribute in the user's entry
        specified by the <code>userRoleName</code> property.</p>
      </attribute>

      <attribute name="roleSearchAsUser" required="false">
        <p> When searching for user roles, should the search be performed as the
        user currently being authenticated? If false,
        <code>connectionName</code> and <code>connectionPassword</code> will be
        used if specified, else an anonymous. If not specified, the default
        value of <code>false</code> is used. Note that when accessing the
        directory using delegated credentials, this attribute is always ignored
        and the search is performed using the delegated credentials.</p>
      </attribute>

      <attribute name="roleSubtree" required="false">
        <p>Set to <code>true</code> if you want to search the entire
        subtree of the element specified by the <code>roleBase</code>
        property for role entries associated with the user. The
        default value of <code>false</code> causes only the top level
        to be searched.</p>
      </attribute>

      <attribute name="sizeLimit" required="false">
        <p>Specifies the maximum number of records to return when using the
        <code>userSearch</code> attribute. If not specified, the default of
        <code>0</code> is used which indicates no limit.</p>
      </attribute>

      <attribute name="spnegoDelegationQop" required="false">
        <p>When the JNDI Realm is used with the SPNEGO authenticator and
        <code>useDelegatedCredential</code> is <code>true</code> this attribute
        controls the QOP (Quality of Protection) that should be used for
        the connection to the LDAP
        server after authentication. This value is used to set the
        <code>javax.security.sasl.qop</code> environment property for the LDAP
        connection. This attribute should be a comma-separated list of values
        selected from <code>auth-conf</code>, <code>auth-int</code> and
        <code>auth</code>. See <a
        href="http://docs.oracle.com/javase/7/docs/api/javax/security/sasl/Sasl.html#QOP"
        rel="nofollow">Java documentation</a> for more details.</p>
        <p>The default value is <code>auth-conf</code>.</p>
      </attribute>

      <attribute name="sslProtocol" required="false">
        <p>Specifies which ssl protocol should be used, when connecting with
        StartTLS. The default is to let the jre decide. If you need even more
        control, you can specify the <code>SSLSocketFactory</code> to use.</p>
      </attribute>

      <attribute name="sslSocketFactory" required="false">
        <p>Specifies which <code>SSLSocketFactory</code> to use when connecting
        to the ldap server using StartTLS. An instance of the class will be
        constructed using the default constructor. If none class name is given
        the default jre <code>SSLSocketFactory</code> will be used.</p>
      </attribute>

      <attribute name="stripRealmForGss" required="false">
        <p>When processing users authenticated via the GSS-API, this attribute
        controls if any &quot;@...&quot; is removed from the end of the user
        name. If not specified, the default is <code>true</code>.</p>
      </attribute>

      <attribute name="timeLimit" required="false">
        <p>Specifies the time (in milliseconds) to wait for records to be
        returned when using the <code>userSearch</code> attribute. If not
        specified, the default of <code>0</code> is used which indicates no
        limit.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

      <attribute name="useContextClassLoader" required="false">
        <p>Instructs JNDIRealm to use the context class loader when opening the
        connection for the JNDI provider. The default value is
        <code>true</code>. To load classes using the container's classloader,
        specify <code>false</code>.</p>
      </attribute>

      <attribute name="useDelegatedCredential" required="false">
        <p>When the JNDIRealm is used with the SPNEGO authenticator, delegated
        credentials for the user may be available. If such credentials are
        present, this attribute controls whether or not they are used to
        connect to the directory. If not specified, the default value of
        <code>true</code> is used.</p>
      </attribute>

      <attribute name="userBase" required="false">
        <p>The base element for user searches performed using the
        <code>userSearch</code> expression.  Not used if you are using
        the <code>userPattern</code> expression.</p>
      </attribute>

      <attribute name="userPassword" required="false">
        <p>Name of the attribute in the user's entry containing the
        user's password.  If you specify this value, JNDIRealm will
        bind to the directory using the values specified by
        <code>connectionName</code> and
        <code>connectionPassword</code> properties, and retrieve the
        corresponding attribute for comparison to the value specified
        by the user being authenticated.  If you do
        <strong>not</strong> specify this value, JNDIRealm will
        attempt a simple bind to the directory using the DN of the
        user's entry and the password presented by the user, with a
        successful bind being interpreted as an authenticated
        user.</p>
      </attribute>

      <attribute name="userPattern" required="false">
        <p>Pattern for the distinguished name (DN) of the user's
        directory entry, with <code>{0}</code> marking where the
        actual username should be inserted. You can use this property
        instead of <code>userSearch</code>, <code>userSubtree</code>
        and <code>userBase</code> when the distinguished name contains
        the username and is otherwise the same for all users. Note that
        when accessing the directory using delegated credentials, this
        attribute is always ignored and <code>userSearch</code>,
        <code>userSubtree</code> and <code>userBase</code> are always
        used instead.</p>
      </attribute>

      <attribute name="userRoleName" required="false">
        <p>The name of an attribute in the user's directory entry
        containing zero or more values for the names of roles assigned
        to this user.  In addition you can use the
        <code>roleName</code> property to specify the name of an
        attribute to be retrieved from individual role entries found
        by searching the directory. If <code>userRoleName</code> is
        not specified all the roles for a user derive from the role
        search.</p>
      </attribute>

      <attribute name="userRoleAttribute" required="false">
        <p>The name of an attribute in the user's directory entry
        containing the value that you wish to use when you search for
        roles. This is especially useful for RFC 2307 where
        the role memberUid can be the <code>uid</code> or the
        <code>uidNumber</code> of the user. This value will be
        marked as <code>{2}</code> in your role search filter expression.
        This value will NOT be available for nested role searches.</p>
      </attribute>

      <attribute name="userSearch" required="false">
        <p>The LDAP filter expression to use when searching for a
        user's directory entry, with <code>{0}</code> marking where
        the actual username should be inserted.  Use this property
        (along with the <code>userBase</code> and
        <code>userSubtree</code> properties) instead of
        <code>userPattern</code> to search the directory for the
        user's entry.</p>
      </attribute>

      <attribute name="userSearchAsUser" required="false">
        <p> When searching for a user's entry, should the search be performed as
        the user currently being authenticated? If false,
        <code>connectionName</code> and <code>connectionPassword</code> will be
        used if specified, else an anonymous. If not specified, the default
        value of <code>false</code> is used. Note that when accessing the
        directory using delegated credentials, this attribute is always ignored
        and the search is performed using the delegated credentials.</p>
      </attribute>

      <attribute name="userSubtree" required="false">
        <p>Set to <code>true</code> if you want to search the entire
        subtree of the element specified by the <code>userBase</code>
        property for the user's entry. The default value of
        <code>false</code> causes only the top level to be searched.
        Not used if you are using the <code>userPattern</code>
        expression.</p>
      </attribute>

      <attribute name="useStartTls" required="false">
        <p>Set to <code>true</code> if you want to use StartTLS for securing
        the connection to the ldap server. The default value is <code>false</code>.
        </p>
      </attribute>

      <attribute name="X509UsernameRetrieverClassName" required="false">
        <p>When using X509 client certificates, this specifies the class name
        that will be used to retrieve the user name from the certificate.
        The class must implement the
        <code>org.apache.catalina.realm.X509UsernameRetriever</code>
        interface. The default is to use the certificate's SubjectDN
        as the username.</p>
      </attribute>
    </attributes>

    <p>See the <a href="../realm-howto.html">Container-Managed Security Guide</a> for more
    information on setting up container managed security using the
    JNDI Directory Realm component.</p>

  </subsection>


  <subsection name="UserDatabase Realm - org.apache.catalina.realm.UserDatabaseRealm">

    <p>The <strong>UserDatabase Realm</strong> is a Realm implementation
    that is based on a UserDatabase resource made available through the global
    JNDI resources configured for this Tomcat instance.</p>

    <p>The UserDatabase Realm implementation supports the following
    additional attributes:</p>

    <attributes>

      <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
      </attribute>

      <attribute name="localJndiResource" required="false">
        <p>When the realm is nested inside a Context element, this allows the
        realm to use a UserDatabase defined for the Context rather than a global
        UserDatabase. If not specified, the default is <code>false</code>: use a
        global UserDatabase.</p>
      </attribute>

      <attribute name="resourceName" required="true">
        <p>The name of the global <code>UserDatabase</code> resource
        that this realm will use for user, password and role information.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

      <attribute name="X509UsernameRetrieverClassName" required="false">
        <p>When using X509 client certificates, this specifies the class name
        that will be used to retrieve the user name from the certificate.
        The class must implement the
        <code>org.apache.catalina.realm.X509UsernameRetriever</code>
        interface. The default is to use the certificate's SubjectDN
        as the username.</p>
      </attribute>
    </attributes>

    <p>See the
    <a href="../realm-howto.html">Container-Managed Security Guide</a> for more
    information on setting up container managed security using the UserDatabase
    Realm component and the
    <a href="../jndi-resources-howto.html">JNDI resources how-to</a> for more
    information on how to configure a UserDatabase resource.</p>

  </subsection>


  <subsection name="Memory Based Realm - org.apache.catalina.realm.MemoryRealm">

    <p>The <strong>Memory Based Realm</strong> is a simple Realm implementation
    that reads user information from an XML format, and represents it as a
    collection of Java objects in memory.  This implementation is intended
    solely to get up and running with container managed security - it is NOT
    intended for production use.  As such, there are no mechanisms for
    updating the in-memory collection of users when the content of the
    underlying data file is changed.</p>

    <p>The Memory Based Realm implementation supports the following
    additional attributes:</p>

    <attributes>

      <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
      </attribute>

      <attribute name="pathname" required="false">
        <p>URL, absolute path or relative path (to $CATALINA_BASE) for the XML
        file containing our user information.  See below for details on the
        XML element format required.  If no pathname is specified, the
        default value is <code>conf/tomcat-users.xml</code>.</p>
      </attribute>

      <attribute name="stripRealmForGss" required="false">
        <p>When processing users authenticated via the GSS-API, this attribute
        controls if any &quot;@...&quot; is removed from the end of the user
        name. If not specified, the default is <code>true</code>.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

      <attribute name="X509UsernameRetrieverClassName" required="false">
        <p>When using X509 client certificates, this specifies the class name
        that will be used to retrieve the user name from the certificate.
        The class must implement the
        <code>org.apache.catalina.realm.X509UsernameRetriever</code>
        interface. The default is to use the certificate's SubjectDN
        as the username.</p>
      </attribute>
    </attributes>

    <p>The XML document referenced by the <code>pathname</code> attribute must
    conform to the following requirements:</p>
    <ul>
    <li>The root (outer) element must be <code>&lt;tomcat-users&gt;</code>.
        </li>
    <li>Each authorized user must be represented by a single XML element
        <code>&lt;user&gt;</code>, nested inside the root element.</li>
    <li>Each <code>&lt;user&gt;</code> element must have the following
        attributes:
        <ul>
        <li><strong>username</strong> - Username of this user (must be unique
            within this file).<br/>
            For compatibility, it is allowed to use <strong>name</strong> as an
            alternative name for this attribute.</li>
        <li><strong>password</strong> - Password of this user (in
            clear text).</li>
        <li><strong>roles</strong> - Comma-delimited list of the role names
            assigned to this user.</li>
        </ul></li>
    </ul>

    <p>See the <a href="../realm-howto.html">Container-Managed Security Guide</a> for more
    information on setting up container managed security using the
    Memory Based Realm component.</p>

  </subsection>


  <subsection name="JAAS Realm - org.apache.catalina.realm.JAASRealm">

    <p><strong>JAASRealm</strong> is an implementation of the Tomcat
    <code>Realm</code> interface that authenticates users through the Java
    Authentication &amp; Authorization Service (JAAS) framework which is now
    provided as part of the standard J2SE API.</p>

    <p>Using JAASRealm gives the developer the ability to combine practically
    any conceivable security realm with Tomcat's CMA.</p>

    <p>JAASRealm is prototype for Tomcat of the JAAS-based J2EE authentication
    framework for J2EE v1.4, based on the <a
    href="https://www.jcp.org/en/jsr/detail?id=196">JCP Specification Request
    196</a> to enhance container-managed security and promote 'pluggable'
    authentication mechanisms whose implementations would be
    container-independent.</p>

    <p>Based on the JAAS login module and principal
    (see <code>javax.security.auth.spi.LoginModule</code> and
    <code>javax.security.Principal</code>), you can develop your own security
    mechanism or wrap another third-party mechanism for integration with the CMA
    as implemented by Tomcat.</p>

    <p>The JAAS Realm implementation supports the following additional
    attributes:</p>

    <attributes>

      <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
      </attribute>

      <attribute name="appName" required="false">
       <p>The name of the application as configured in your login configuration
       file
       (<a href="http://docs.oracle.com/javase/1.4.2/docs/guide/security/jaas/tutorials/LoginConfigFile.html">JAAS LoginConfig</a>).</p>
       <p>If not specified <code>appName</code> is derived from the Container's
       name it is placed in, for example <code>Catalina</code> or <code>ROOT</code>.
       If the realm is not placed in any Container, the default is <code>Tomcat</code>.
       </p>
      </attribute>

      <attribute name="userClassNames" required="true">
        <p>A comma-separated list of the names of the classes that you have made
        for your user <code>Principals</code>.</p>
      </attribute>

      <attribute name="configFile" required="false">
        <p>The name of a JAAS configuration file to use with this Realm. It will
        be searched for using <code>ClassLoader#getResource(String)</code> so it
        is possible for the configuration to be bundled within a web
        application. If not specified, the default JVM global JAAS configuration
        will be used.</p>
      </attribute>

      <attribute name="roleClassNames" required="false">
        <p>A comma-separated list of the names of the classes that you have made
        for your role <code>Principals</code>.</p>
      </attribute>

      <attribute name="stripRealmForGss" required="false">
        <p>When processing users authenticated via the GSS-API, this attribute
        controls if any &quot;@...&quot; is removed from the end of the user
        name. If not specified, the default is <code>true</code>.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

      <attribute name="useContextClassLoader" required="false">
        <p>Instructs JAASRealm to use the context class loader for loading the
        user-specified <code>LoginModule</code> class and associated
        <code>Principal</code> classes. The default value is <code>true</code>,
        which is backwards-compatible with the way Tomcat 5 works. To load
        classes using the container's classloader, specify
        <code>false</code>.</p>
      </attribute>

      <attribute name="X509UsernameRetrieverClassName" required="false">
        <p>When using X509 client certificates, this specifies the class name
        that will be used to retrieve the user name from the certificate.
        The class must implement the
        <code>org.apache.catalina.realm.X509UsernameRetriever</code>
        interface. The default is to use the certificate's SubjectDN
        as the username.</p>
      </attribute>
    </attributes>

    <p>See the <a href="../realm-howto.html">Container-Managed Security
    Guide</a> for more information on setting up container managed security
    using the JAAS Realm component.</p>

  </subsection>


  <subsection name="Combined Realm - org.apache.catalina.realm.CombinedRealm">

    <p><strong>CombinedRealm</strong> is an implementation of the Tomcat
    <code>Realm</code> interface that authenticates users through one or more
    sub-Realms.</p>

    <p>Using CombinedRealm gives the developer the ability to combine multiple
    Realms of the same or different types. This can be used to authenticate
    against different sources, provide fall back in case one Realm fails or for
    any other purpose that requires multiple Realms.</p>

    <p>Sub-realms are defined by nesting <code>Realm</code> elements inside the
    <code>Realm</code> element that defines the CombinedRealm. Authentication
    will be attempted against each <code>Realm</code> in the order they are
    listed. Authentication against any Realm will be sufficient to authenticate
    the user. The authenticated user, and their associated roles, will be taken
    from the first Realm that successfully authenticates the user.</p>

    <p>See the <a href="../realm-howto.html">Container-Managed Security
    Guide</a> for more information on setting up container managed security
    using the CombinedRealm component.</p>

    <p>The CombinedRealm implementation supports the following additional
    attributes.</p>

    <attributes>

      <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

    </attributes>
  </subsection>


  <subsection name="LockOut Realm - org.apache.catalina.realm.LockOutRealm">

    <p><strong>LockOutRealm</strong> is an implementation of the Tomcat
    <code>Realm</code> interface that extends the CombinedRealm to provide lock
    out functionality to provide a user lock out mechanism if there are too many
    failed authentication attempts in a given period of time.</p>

    <p>To ensure correct operation, there is a reasonable degree of
    synchronization in this Realm.</p>

    <p>This Realm does not require modification to the underlying Realms or the
    associated user storage mechanisms. It achieves this by recording all failed
    logins, including those for users that do not exist. To prevent a DOS by
    deliberating making requests with invalid users (and hence causing this
    cache to grow) the size of the list of users that have failed authentication
    is limited.</p>

    <p>Sub-realms are defined by nesting <code>Realm</code> elements inside the
    <code>Realm</code> element that defines the LockOutRealm. Authentication
    will be attempted against each <code>Realm</code> in the order they are
    listed. Authentication against any Realm will be sufficient to authenticate
    the user.</p>

    <p>The LockOutRealm implementation supports the following additional
    attributes.</p>

    <attributes>
       <attribute name="allRolesMode" required="false">
        <p>This attribute controls how the special role name <code>*</code> is
        handled when processing authorization constraints in web.xml. By
        default, the specification compliant value of <code>strict</code> is
        used which means that the user must be assigned one of the roles defined
        in web.xml. The alternative values are <code>authOnly</code> which means
        that the user must be authenticated but no check is made for assigned
        roles and <code>strictAuthOnly</code> which means that the user must be
        authenticated and no check will be made for assigned roles unless roles
        are defined in web.xml in which case the user must be assigned at least
        one of those roles.</p>
      </attribute>

      <attribute name="cacheRemovalWarningTime" required="false">
       <p>If a failed user is removed from the cache because the cache is too
       big before it has been in the cache for at least this period of time (in
       seconds) a warning message will be logged. Defaults to 3600 (1 hour).</p>
      </attribute>

      <attribute name="cacheSize" required="false">
       <p>Number of users that have failed authentication to keep in cache. Over
       time the cache will grow to this size and may not shrink. Defaults to
       1000.</p>
      </attribute>

      <attribute name="failureCount" required="false">
       <p>The number of times in a row a user has to fail authentication to be
       locked out. Defaults to 5.</p>
      </attribute>

      <attribute name="lockOutTime" required="false">
       <p>The time (in seconds) a user is locked out for after too many
       authentication failures. Defaults to 300 (5 minutes). Further
       authentication failures during the lock out time will cause the lock out
       timer to reset to zero, effectively extending the lock out time. Valid
       authentication attempts during the lock out period will not succeed but
       will also not reset the lock out time.</p>
      </attribute>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

    </attributes>

    <p>See the <a href="../realm-howto.html">Container-Managed Security
    Guide</a> for more information on setting up container managed security
    using the LockOutRealm component.</p>

  </subsection>

  <subsection name="Null Realm - org.apache.catalina.realm.NullRealm">

    <p><strong>NullRealm</strong> is a minimal implementation of the Tomcat
    <code>Realm</code> interface that always returns null when an attempt is
    made to validate a user name and associated credentials. It is intended to
    be used as a default Realm implementation when no other Realm is
    specified.</p>

    <p>The NullRealm implementation supports the following additional
    attributes.</p>

    <attributes>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

    </attributes>

  </subsection>

  <subsection name="Authenticated User Realm - org.apache.catalina.realm.AuthenticatedUserRealm">

    <p><strong>AuthenticatedUserRealm</strong> is intended for use with
    Authenticator implementations (SSLAuthenticator, SpnegoAuthenticator) that
    authenticate the user as well as obtain the user credentials. An
    authenticated Principal is always created from the user name presented to
    without further validation.</p>
    <p><strong>Note:</strong> It is unsafe to use this Realm with Authenticator
    implementations that do not validate the provided credentials.</p>

    <p>The AuthenticatedUserRealm implementation supports the following
    additional attributes.</p>

    <attributes>

      <attribute name="transportGuaranteeRedirectStatus" required="false">
        <p>The HTTP status code to use when the container needs to issue an HTTP
           redirect to meet the requirements of a configured transport
           guarantee. The provided status code is not validated. If not
           specified, the default value of <code>302</code> is used.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Nested Components">

  <p>You can nest the following components by nesting the corresponding element
  inside your <strong>Realm</strong> element:</p>
  <ul>
  <li><strong>CombinedRealm Implementation</strong> - If you are using the
    <em>CombinedRealm Implementation</em> or a Realm
    that extends the CombinedRealm, e.g. the LockOutRealm, one or more
    <strong>&lt;Realm&gt;</strong> elements may be nested inside it.</li>
  <li><a href="credentialhandler.html"><strong>CredentialHandler</strong></a> -
      You may nest at most one instance of this element inside a Realm. This
      configures the credential handler that will be used to validate provided
      credentials with those stored by the Realm. If not specified a default
      <em>MessageDigestCredentialHandler</em> will be configured.</li>
  </ul>

</section>


<section name="Special Features">

  <p>See <a href="host.html">Single Sign On</a> for information about
  configuring Single Sign On support for a virtual host.</p>

</section>


</body>


</document>
