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| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>21.10. LDAP Authentication</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="auth-peer.html" title="21.9. Peer Authentication" /><link rel="next" href="auth-radius.html" title="21.11. RADIUS Authentication" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">21.10. LDAP Authentication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="auth-peer.html" title="21.9. Peer Authentication">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="client-authentication.html" title="Chapter 21. Client Authentication">Up</a></td><th width="60%" align="center">Chapter 21. Client Authentication</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="auth-radius.html" title="21.11. RADIUS Authentication">Next</a></td></tr></table><hr /></div><div class="sect1" id="AUTH-LDAP"><div class="titlepage"><div><div><h2 class="title" style="clear: both">21.10. LDAP Authentication <a href="#AUTH-LDAP" class="id_link">#</a></h2></div></div></div><a id="id-1.6.8.17.2" class="indexterm"></a><p> |
| This authentication method operates similarly to |
| <code class="literal">password</code> except that it uses LDAP |
| as the password verification method. LDAP is used only to validate |
| the user name/password pairs. Therefore the user must already |
| exist in the database before LDAP can be used for |
| authentication. |
| </p><p> |
| LDAP authentication can operate in two modes. In the first mode, |
| which we will call the simple bind mode, |
| the server will bind to the distinguished name constructed as |
| <em class="replaceable"><code>prefix</code></em> <em class="replaceable"><code>username</code></em> <em class="replaceable"><code>suffix</code></em>. |
| Typically, the <em class="replaceable"><code>prefix</code></em> parameter is used to specify |
| <code class="literal">cn=</code>, or <em class="replaceable"><code>DOMAIN</code></em><code class="literal">\</code> in an Active |
| Directory environment. <em class="replaceable"><code>suffix</code></em> is used to specify the |
| remaining part of the DN in a non-Active Directory environment. |
| </p><p> |
| In the second mode, which we will call the search+bind mode, |
| the server first binds to the LDAP directory with |
| a fixed user name and password, specified with <em class="replaceable"><code>ldapbinddn</code></em> |
| and <em class="replaceable"><code>ldapbindpasswd</code></em>, and performs a search for the user trying |
| to log in to the database. If no user and password is configured, an |
| anonymous bind will be attempted to the directory. The search will be |
| performed over the subtree at <em class="replaceable"><code>ldapbasedn</code></em>, and will try to |
| do an exact match of the attribute specified in |
| <em class="replaceable"><code>ldapsearchattribute</code></em>. |
| Once the user has been found in |
| this search, the server disconnects and re-binds to the directory as |
| this user, using the password specified by the client, to verify that the |
| login is correct. This mode is the same as that used by LDAP authentication |
| schemes in other software, such as Apache <code class="literal">mod_authnz_ldap</code> and <code class="literal">pam_ldap</code>. |
| This method allows for significantly more flexibility |
| in where the user objects are located in the directory, but will cause |
| two separate connections to the LDAP server to be made. |
| </p><p> |
| The following configuration options are used in both modes: |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">ldapserver</code></span></dt><dd><p> |
| Names or IP addresses of LDAP servers to connect to. Multiple |
| servers may be specified, separated by spaces. |
| </p></dd><dt><span class="term"><code class="literal">ldapport</code></span></dt><dd><p> |
| Port number on LDAP server to connect to. If no port is specified, |
| the LDAP library's default port setting will be used. |
| </p></dd><dt><span class="term"><code class="literal">ldapscheme</code></span></dt><dd><p> |
| Set to <code class="literal">ldaps</code> to use LDAPS. This is a non-standard |
| way of using LDAP over SSL, supported by some LDAP server |
| implementations. See also the <code class="literal">ldaptls</code> option for |
| an alternative. |
| </p></dd><dt><span class="term"><code class="literal">ldaptls</code></span></dt><dd><p> |
| Set to 1 to make the connection between PostgreSQL and the LDAP server |
| use TLS encryption. This uses the <code class="literal">StartTLS</code> |
| operation per <a class="ulink" href="https://datatracker.ietf.org/doc/html/rfc4513" target="_top">RFC 4513</a>. |
| See also the <code class="literal">ldapscheme</code> option for an alternative. |
| </p></dd></dl></div><p> |
| </p><p> |
| Note that using <code class="literal">ldapscheme</code> or |
| <code class="literal">ldaptls</code> only encrypts the traffic between the |
| PostgreSQL server and the LDAP server. The connection between the |
| PostgreSQL server and the PostgreSQL client will still be unencrypted |
| unless SSL is used there as well. |
| </p><p> |
| The following options are used in simple bind mode only: |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">ldapprefix</code></span></dt><dd><p> |
| String to prepend to the user name when forming the DN to bind as, |
| when doing simple bind authentication. |
| </p></dd><dt><span class="term"><code class="literal">ldapsuffix</code></span></dt><dd><p> |
| String to append to the user name when forming the DN to bind as, |
| when doing simple bind authentication. |
| </p></dd></dl></div><p> |
| </p><p> |
| The following options are used in search+bind mode only: |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">ldapbasedn</code></span></dt><dd><p> |
| Root DN to begin the search for the user in, when doing search+bind |
| authentication. |
| </p></dd><dt><span class="term"><code class="literal">ldapbinddn</code></span></dt><dd><p> |
| DN of user to bind to the directory with to perform the search when |
| doing search+bind authentication. |
| </p></dd><dt><span class="term"><code class="literal">ldapbindpasswd</code></span></dt><dd><p> |
| Password for user to bind to the directory with to perform the search |
| when doing search+bind authentication. |
| </p></dd><dt><span class="term"><code class="literal">ldapsearchattribute</code></span></dt><dd><p> |
| Attribute to match against the user name in the search when doing |
| search+bind authentication. If no attribute is specified, the |
| <code class="literal">uid</code> attribute will be used. |
| </p></dd><dt><span class="term"><code class="literal">ldapsearchfilter</code></span></dt><dd><p> |
| The search filter to use when doing search+bind authentication. |
| Occurrences of <code class="literal">$username</code> will be replaced with the |
| user name. This allows for more flexible search filters than |
| <code class="literal">ldapsearchattribute</code>. |
| </p></dd><dt><span class="term"><code class="literal">ldapurl</code></span></dt><dd><p> |
| An <a class="ulink" href="https://datatracker.ietf.org/doc/html/rfc4516" target="_top">RFC 4516</a> |
| LDAP URL. This is an alternative way to write some of the |
| other LDAP options in a more compact and standard form. The format is |
| </p><pre class="synopsis"> |
| ldap[s]://<em class="replaceable"><code>host</code></em>[:<em class="replaceable"><code>port</code></em>]/<em class="replaceable"><code>basedn</code></em>[?[<em class="replaceable"><code>attribute</code></em>][?[<em class="replaceable"><code>scope</code></em>][?[<em class="replaceable"><code>filter</code></em>]]]] |
| </pre><p> |
| <em class="replaceable"><code>scope</code></em> must be one |
| of <code class="literal">base</code>, <code class="literal">one</code>, <code class="literal">sub</code>, |
| typically the last. (The default is <code class="literal">base</code>, which |
| is normally not useful in this application.) <em class="replaceable"><code>attribute</code></em> can |
| nominate a single attribute, in which case it is used as a value for |
| <code class="literal">ldapsearchattribute</code>. If |
| <em class="replaceable"><code>attribute</code></em> is empty then |
| <em class="replaceable"><code>filter</code></em> can be used as a value for |
| <code class="literal">ldapsearchfilter</code>. |
| </p><p> |
| The URL scheme <code class="literal">ldaps</code> chooses the LDAPS method for |
| making LDAP connections over SSL, equivalent to using |
| <code class="literal">ldapscheme=ldaps</code>. To use encrypted LDAP |
| connections using the <code class="literal">StartTLS</code> operation, use the |
| normal URL scheme <code class="literal">ldap</code> and specify the |
| <code class="literal">ldaptls</code> option in addition to |
| <code class="literal">ldapurl</code>. |
| </p><p> |
| For non-anonymous binds, <code class="literal">ldapbinddn</code> |
| and <code class="literal">ldapbindpasswd</code> must be specified as separate |
| options. |
| </p><p> |
| LDAP URLs are currently only supported with |
| <span class="productname">OpenLDAP</span>, not on Windows. |
| </p></dd></dl></div><p> |
| </p><p> |
| It is an error to mix configuration options for simple bind with options |
| for search+bind. |
| </p><p> |
| When using search+bind mode, the search can be performed using a single |
| attribute specified with <code class="literal">ldapsearchattribute</code>, or using |
| a custom search filter specified with |
| <code class="literal">ldapsearchfilter</code>. |
| Specifying <code class="literal">ldapsearchattribute=foo</code> is equivalent to |
| specifying <code class="literal">ldapsearchfilter="(foo=$username)"</code>. If neither |
| option is specified the default is |
| <code class="literal">ldapsearchattribute=uid</code>. |
| </p><p> |
| If <span class="productname">PostgreSQL</span> was compiled with |
| <span class="productname">OpenLDAP</span> as the LDAP client library, the |
| <code class="literal">ldapserver</code> setting may be omitted. In that case, a |
| list of host names and ports is looked up via |
| <a class="ulink" href="https://datatracker.ietf.org/doc/html/rfc2782" target="_top">RFC 2782</a> DNS SRV records. |
| The name <code class="literal">_ldap._tcp.DOMAIN</code> is looked up, where |
| <code class="literal">DOMAIN</code> is extracted from <code class="literal">ldapbasedn</code>. |
| </p><p> |
| Here is an example for a simple-bind LDAP configuration: |
| </p><pre class="programlisting"> |
| host ... ldap ldapserver=ldap.example.net ldapprefix="cn=" ldapsuffix=", dc=example, dc=net" |
| </pre><p> |
| When a connection to the database server as database |
| user <code class="literal">someuser</code> is requested, PostgreSQL will attempt to |
| bind to the LDAP server using the DN <code class="literal">cn=someuser, dc=example, |
| dc=net</code> and the password provided by the client. If that connection |
| succeeds, the database access is granted. |
| </p><p> |
| Here is an example for a search+bind configuration: |
| </p><pre class="programlisting"> |
| host ... ldap ldapserver=ldap.example.net ldapbasedn="dc=example, dc=net" ldapsearchattribute=uid |
| </pre><p> |
| When a connection to the database server as database |
| user <code class="literal">someuser</code> is requested, PostgreSQL will attempt to |
| bind anonymously (since <code class="literal">ldapbinddn</code> was not specified) to |
| the LDAP server, perform a search for <code class="literal">(uid=someuser)</code> |
| under the specified base DN. If an entry is found, it will then attempt to |
| bind using that found information and the password supplied by the client. |
| If that second connection succeeds, the database access is granted. |
| </p><p> |
| Here is the same search+bind configuration written as a URL: |
| </p><pre class="programlisting"> |
| host ... ldap ldapurl="ldap://ldap.example.net/dc=example,dc=net?uid?sub" |
| </pre><p> |
| Some other software that supports authentication against LDAP uses the |
| same URL format, so it will be easier to share the configuration. |
| </p><p> |
| Here is an example for a search+bind configuration that uses |
| <code class="literal">ldapsearchfilter</code> instead of |
| <code class="literal">ldapsearchattribute</code> to allow authentication by |
| user ID or email address: |
| </p><pre class="programlisting"> |
| host ... ldap ldapserver=ldap.example.net ldapbasedn="dc=example, dc=net" ldapsearchfilter="(|(uid=$username)(mail=$username))" |
| </pre><p> |
| </p><p> |
| Here is an example for a search+bind configuration that uses DNS SRV |
| discovery to find the host name(s) and port(s) for the LDAP service for the |
| domain name <code class="literal">example.net</code>: |
| </p><pre class="programlisting"> |
| host ... ldap ldapbasedn="dc=example,dc=net" |
| </pre><p> |
| </p><div class="tip"><h3 class="title">Tip</h3><p> |
| Since LDAP often uses commas and spaces to separate the different |
| parts of a DN, it is often necessary to use double-quoted parameter |
| values when configuring LDAP options, as shown in the examples. |
| </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="auth-peer.html" title="21.9. Peer Authentication">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="client-authentication.html" title="Chapter 21. Client Authentication">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="auth-radius.html" title="21.11. RADIUS Authentication">Next</a></td></tr><tr><td width="40%" align="left" valign="top">21.9. Peer Authentication </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 21.11. RADIUS Authentication</td></tr></table></div></body></html> |
