SEC-626: Update Ldap configuration section
http://jira.springframework.org/browse/SEC-626
This commit is contained in:
Luke Taylor
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@ -17,16 +17,132 @@
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setting up a directory using the free LDAP server OpenLDAP: <ulink
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url="http://www.zytrax.com/books/ldap/"/>. Some familiarity with the JNDI APIs used
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to access LDAP from Java may also be useful. We don't use any third-party LDAP libraries
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(Mozilla/Netscape, JLDAP etc.) in the LDAP provider.</para>
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(Mozilla, JLDAP etc.) in the LDAP provider, but extensive use is made of Spring LDAP, so
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some familiarity with that project may be useful if you plan on adding your own
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customizations.</para>
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</sect1>
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<sect1 id="ldap-with-acegi">
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<sect1>
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<title>Using LDAP with Spring Security</title>
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<para>The main LDAP provider class is
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<para> LDAP authentication in Spring Security can be roughly divided into the following
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stages. <orderedlist>
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<listitem>
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<para>Obtaining the unique LDAP <quote>Distinguished Name</quote>, or DN, from
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the login name. This will often mean performing a search in the directory,
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unless the exact mapping of usernames to DNs is known in advance.</para>
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</listitem>
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<listitem>
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<para>Authenticating the user, either by binding as that user or by performing a
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remote <quote>compare</quote> operation of the user's password against the
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password attribute in the directory entry for the DN.</para>
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</listitem>
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<listitem>
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<para>Loading the list of authorities for the user.</para>
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</listitem>
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</orderedlist> The exception is when the LDAP directory is just being used to retrieve
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user information and authenticate against it locally. This may not be possible as
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directories are often set up with limited read access for attributes such as user
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passwords. </para>
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<para> We will look at some configuration scenarios below. For full information on available
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configuration options, please consult the security namespace schema (information from
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which should be available in your XML editor). </para>
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</sect1>
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<sect1>
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<title>Configuring an LDAP Server</title>
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<para> The first thing you need to do is configure the server against which authentication
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should take place. This is done using the <literal><ldap-server></literal> element
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from the security namespace. This can be configured to point at an external LDAP server,
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using the <literal>url</literal> attribute: <programlisting><![CDATA[
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<ldap-server url="ldap://springframework.org:389/dc=springframework,dc=org" />
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]]></programlisting></para>
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<sect2>
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<title>Using an Embedded Test Server</title>
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<para> The <literal><ldap-server></literal> element can also be used to create an
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embedded server, which can be very useful for testing and demonstrations. In this
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case you use it without the <literal>url</literal> attribute: <programlisting><![CDATA[
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<ldap-server root="dc=springframework,dc=org"/>
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]]></programlisting> Here we've specified that the root DIT of the directory should be
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<quote>dc=springframework,dc=org</quote>, which is the default. Used this way,
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the namespace parser will create an embedded Apache Directory server and scan the
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classpath for any LDIF files, which it will attempt to load into the server. You can
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customize this behaviour using the <literal>ldif</literal> attribute, which defines
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an LDIF resource to be loaded: <programlisting><![CDATA[
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<ldap-server ldif="classpath:users.ldif" />
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]]></programlisting> This makes it a lot easier to get up and running with LDAP, since it can be
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inconvenient to work all the time with an external server. It also insulates the
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user from the complex bean configuration needed to wire up an Apache Directory
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server. Using plain Spring Beans the configuration would be much more cluttered. You
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must have the necessary Apache Directory dependency jars available for your
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application to use. These can be obtained from the <olink targetdoc="sample-apps"
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targetptr="ldap">LDAP sample application</olink>. </para>
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</sect2>
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<sect2>
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<title>Using Bind Authentication</title>
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<para> This is the most common LDAP authentication scenario. <programlisting>
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<![CDATA[
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<ldap-authentication-provider user-dn-pattern="uid={0},ou=people"/>
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]]></programlisting> This simple example would obtain the DN for the user by
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substituting the user login name in the supplied pattern and attempting to bind as
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that user with the login password. This is OK if all your users are stored under a
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single node in the directory. If instead you wished to configure an LDAP search
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filter to locate the user, you could use the following: <programlisting>
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<![CDATA[
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<ldap-authentication-provider user-search-filter="(uid={0})" user-search-base="ou=people"/>
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]]></programlisting> If used with the server definition above, this would
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perform a search under the DN <literal>ou=people,dc=springframework,dc=org</literal>
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using the value of the <literal>user-search-filter</literal> attribute as a filter.
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Again the user login name is substituted for the parameter in the filter name. If
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<literal>user-search-base</literal> isn't supplied, the search will be performed
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from the root. </para>
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</sect2>
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<sect2>
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<title>Loading Authorities</title>
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<para> How authorities are loaded from groups in the LDAP directory is controlled by the
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following attributes. <itemizedlist>
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<listitem>
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<para><literal>group-search-base</literal>. Defines the part of the
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directory tree under which group searches should be performed.</para>
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</listitem>
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<listitem>
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<para><literal>group-role-attribute</literal>. The attribute which contains
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the name of the authority defined by the group entry. Defaults to
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<literal>cn</literal></para>
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</listitem>
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<listitem>
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<para><literal>group-search-filter</literal>. The filter which is used to
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search for group membership. The default is <literal
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>uniqueMember={0}</literal>, corresponding to the <literal
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>groupOfUniqueMembers</literal> LDAP class. In this case, the
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substituted parameter is the full distinguished name of the user. The
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parameter <literal>{1}</literal> can be used if you want to filter on
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the login name.</para>
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</listitem>
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</itemizedlist> So if we used the following configuration <programlisting>
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<![CDATA[
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<ldap-authentication-provider user-dn-pattern="uid={0},ou=people group-search-base="ou=groups" />
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]]></programlisting> and authenticated successfully as user <quote>ben</quote>,
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the subsequent loading of authorities would perform a search under the directory
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entry <literal>ou=groups,dc=springframework,dc=org</literal>, looking for entries
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which contain the attribute <literal>uniqueMember</literal> with value <literal
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>uid=ben,ou=people,dc=springframework,dc=org</literal>. For more information on
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loading authorities, see the Javadoc for the
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<classname>DefaultLdapAuthoritiesPopulator</classname> class. </para>
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</sect2>
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</sect1>
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<sect1>
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<title>Implementation Classes</title>
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<para>The namespace configuration options we've used above are simple to use and much more
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concise than using Spring beans explicitly. There are situations when you may need to
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know how to configure Spring Security LDAP directly in your application context. You may
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wish to customize the behaviour of some of the classes, for example. If you're happy using
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namespace configuration then you can skip this section and the next one.
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</para>
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<para>
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The main LDAP
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provider class is
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<classname>org.springframework.security.providers.ldap.LdapAuthenticationProvider</classname>.
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This bean doesn't actually do much itself other than implement the
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<methodname>retrieveUser</methodname> method required by its base class,
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<classname>AbstractUserDetailsAuthenticationProvider</classname>. It delegates the
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work to two other beans, an <interfacename>LdapAuthenticator</interfacename> and an
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This bean doesn't actually do much itself but delegates the work to two other beans, an
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<interfacename>LdapAuthenticator</interfacename> and an
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<interfacename>LdapAuthoritiesPopulator</interfacename> which are responsible for
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authenticating the user and retrieving the user's set of
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<interfacename>GrantedAuthority</interfacename>s respectively.</para>
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@ -61,10 +177,9 @@
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substituted for the parameter <parameter>{0}</parameter>. The pattern should be
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relative to the DN that the configured
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<interfacename>InitialDirContextFactory</interfacename> will bind to (see the
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section on <link linkend="ldap-dircontextfactory">connecting to the LDAP
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section on <link linkend="ldap-context-source">connecting to the LDAP
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server</link> for more information on this). For example, if you are using an
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LDAP server specified by the URL <literal
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>ldap://monkeymachine.co.uk/dc=springframework,dc=org</literal>, and have a
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LDAP server with the URL <literal>ldap://monkeymachine.co.uk/dc=springframework,dc=org</literal>, and have a
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pattern <literal>uid={0},ou=greatapes</literal>, then a login name of "gorilla"
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will map to a DN <literal
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>uid=gorilla,ou=greatapes,dc=springframework,dc=org</literal>. Each configured
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@ -93,27 +208,18 @@
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Directory has its own non-standard syntax for user authentication.</para>
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</sect3>
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</sect2>
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<sect2 id="ldap-dircontextfactory">
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<sect2 id="ldap-context-source">
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<title>Connecting to the LDAP Server</title>
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<para>The beans discussed above have to be able to connect to the server. They both have
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to be supplied with an <interfacename>InitialDirContextFactory</interfacename>
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instance. Unless you have special requirements, this will usually be a
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<classname>DefaultInitialDirContextFactory</classname> bean, which can be
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to be supplied with a <interfacename>SpringSecurityContextSource</interfacename>
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which is an extension of Spring LDAP's <interfacename>ContextSource</interfacename>.
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Unless you have special requirements, you will usually
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configure a <classname>DefaultSpringSecurityContextSource</classname> bean, which can be
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configured with the URL of your LDAP server and optionally with the username and
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password of a "manager" user which will be used by default when binding to the
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server (instead of binding anonymously). It currently supports "simple" LDAP
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authentication.</para>
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<para><classname>DefaultInitialDirContextFactory</classname> uses Sun's JNDI LDAP
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implementation by default (the one that comes with the JDK). It also supports the
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built in connection pooling offered by Sun's provider. Connections which are
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obtained either anonymously or with the "manager" user's identity will be pooled
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automatically. Connections obtained with a specific user's identity will not be
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pooled. Connection pooling can be disabled completely by setting the <property
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>useConnectionPool</property> property to false.</para>
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<para>See the <ulink
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url="http://acegisecurity.org/multiproject/acegi-security/xref/org/acegisecurity/providers/ldap/DefaultInitialDirContextFactory.html"
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>class Javadoc and source</ulink> for more information on this bean and its
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properties.</para>
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server (instead of binding anonymously). For more information read the Javadoc for
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this class and for Spring LDAP's <classname>AbstractContextSource</classname>.
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</para>
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</sect2>
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<sect2 id="ldap-searchobjects">
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<title>LDAP Search Objects</title>
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@ -134,61 +240,58 @@
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>{0}</parameter> which will be replaced with the user's login name.</para>
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</sect3>
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</sect2>
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</sect1>
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<sect1 id="ldap-config">
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<title>Configuration</title>
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<para>There is a version of the <link linkend="contacts-sample">Contacts Sample
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Application</link> which uses LDAP. You can copy the beans and filter setup from this as
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a starting point for configuring your own application.</para>
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<para>A typical configuration, using some of the beans we've discussed above, might look
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like this: <programlisting>
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<![CDATA[
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<bean id="initialDirContextFactory"
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class="org.springframework.security.ldap.DefaultInitialDirContextFactory">
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<sect2 id="ldap-bean-config">
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<title>Spring Bean Configuration</title>
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<para>A typical configuration, using some of the beans we've discussed here, might look
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like this: <programlisting>
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<![CDATA[
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<bean id="contextSource"
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class="org.springframework.security.ldap.DefaultSpringSecurityContextSource">
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<constructor-arg value="ldap://monkeymachine:389/dc=springframework,dc=org"/>
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<property name="managerDn"><value>cn=manager,dc=springframework,dc=org</value></property>
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<property name="managerPassword"><value>password</value></property>
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</bean>
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<bean id="userSearch"
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class="org.springframework.security.ldap.search.FilterBasedLdapUserSearch">
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<constructor-arg index="0" value=""/>
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<constructor-arg index="1" value="(uid={0})"/>
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<constructor-arg index="2">
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<ref local="initialDirContextFactory" />
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</constructor-arg>
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<property name="searchSubtree" value="true"/>
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<property name="userDn" value="cn=manager,dc=springframework,dc=org"/>
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<property name="password" value="password"/>
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</bean>
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<bean id="ldapAuthProvider"
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class="org.springframework.security.providers.ldap.LdapAuthenticationProvider">
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<constructor-arg>
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<bean class="org.springframework.security.providers.ldap.authenticator.BindAuthenticator">
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<constructor-arg><ref local="initialDirContextFactory"/></constructor-arg>
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<constructor-arg ref="contextSource"/>
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<property name="userDnPatterns"><list><value>uid={0},ou=people</value></list></property>
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</bean>
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</constructor-arg>
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<constructor-arg>
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<bean class="org.springframework.security.ldap.populator.DefaultLdapAuthoritiesPopulator">
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<constructor-arg><ref local="initialDirContextFactory"/></constructor-arg>
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<constructor-arg><value>ou=groups</value></constructor-arg>
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<property name="groupRoleAttribute"><value>ou</value></property>
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<constructor-arg ref="contextSource"/>
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<constructor-arg value="ou=groups"/>
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<property name="groupRoleAttribute" value="ou"/>
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</bean>
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</constructor-arg>
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</bean>
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]]>
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</programlisting> This would set up the provider to access an LDAP server with URL
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</programlisting> This would set up the provider to access an LDAP server with URL
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<literal>ldap://monkeymachine:389/dc=springframework,dc=org</literal>.
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Authentication will be performed by attempting to bind with the DN <literal
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>uid=<user-login-name>,ou=people,dc=springframework,dc=org</literal>. After
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successful authentication, roles will be assigned to the user by searching under the DN
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Authentication will be performed by attempting to bind with the DN <literal
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>uid=<user-login-name>,ou=people,dc=springframework,dc=org</literal>. After
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successful authentication, roles will be assigned to the user by searching under the DN
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<literal>ou=groups,dc=springframework,dc=org</literal> with the default filter
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<literal>(member=<user's-DN>)</literal>. The role name will be taken from the
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<quote>ou</quote> attribute of each match.</para>
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<para>We've also included the configuration for a user search object, which uses the filter
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<literal>(uid=<user-login-name>)</literal>. This could be used instead of the
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DN-pattern (or in addition to it), by setting the authenticator's <property
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>userSearch</property> property. The authenticator would then call the search object to
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obtain the correct user's DN before attempting to bind as this user.</para>
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<para>To configurae a user search object, which uses the filter
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<literal>(uid=<user-login-name>)</literal> for use instead of the
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DN-pattern (or in addition to it), you would configure the following bean
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<programlisting><![CDATA[
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<bean id="userSearch"
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class="org.springframework.security.ldap.search.FilterBasedLdapUserSearch">
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<constructor-arg index="0" value=""/>
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<constructor-arg index="1" value="(uid={0})"/>
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<constructor-arg index="2" ref="contextSource" />
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<property name="searchSubtree" value="true"/>
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</bean> ]]>
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</programlisting>
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and use it by setting the authenticator's <property>userSearch</property> property. The authenticator
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would then call the search object to obtain the correct user's DN before attempting to bind as this user.</para>
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</sect2>
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</sect1>
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</chapter>
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