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<modulesynopsis metafile="mod_ldap.xml.meta">

<name>mod_ldap</name>
<description>LDAP connection pooling and result caching services for use
by other LDAP modules</description>
<status>Extension</status>
<sourcefile>util_ldap.c</sourcefile>
<identifier>ldap_module</identifier>

<summary>
    <p>This module was created to improve the performance of
    websites relying on backend connections to LDAP servers. In
    addition to the functions provided by the standard LDAP
    libraries, this module adds an LDAP connection pool and an LDAP
    shared memory cache.</p>

    <p>To enable this module, LDAP support must be compiled into
    apr-util. This is achieved by adding the <code>--with-ldap</code>
    flag to the <program>configure</program> script when building
    Apache.</p>

    <p>SSL/TLS support is dependent on which LDAP toolkit has been
    linked to <glossary>APR</glossary>. As of this writing, APR-util supports:
    <a href="http://www.openldap.org/">OpenLDAP SDK</a> (2.x or later),
    <a href="http://developer.novell.com/ndk/cldap.htm">Novell LDAP
    SDK</a>, <a href="https://wiki.mozilla.org/LDAP_C_SDK">
    Mozilla LDAP SDK</a>, native Solaris LDAP SDK (Mozilla based) or the
    native Microsoft LDAP SDK. See the <a href="http://apr.apache.org">APR</a>
    website for details.</p>

</summary>

<section id="exampleconfig"><title>Example Configuration</title>
    <p>The following is an example configuration that uses
    <module>mod_ldap</module> to increase the performance of HTTP Basic
    authentication provided by <module>mod_authnz_ldap</module>.</p>

    <highlight language="config">
# Enable the LDAP connection pool and shared
# memory cache. Enable the LDAP cache status
# handler. Requires that mod_ldap and mod_authnz_ldap
# be loaded. Change the "yourdomain.example.com" to
# match your domain.

LDAPSharedCacheSize 500000
LDAPCacheEntries 1024
LDAPCacheTTL 600
LDAPOpCacheEntries 1024
LDAPOpCacheTTL 600

&lt;Location "/ldap-status"&gt;
    SetHandler ldap-status

    Require host yourdomain.example.com

    Satisfy any
    AuthType Basic
    AuthName "LDAP Protected"
    AuthBasicProvider ldap
    AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=com?uid?one"
    Require valid-user
&lt;/Location&gt;
    </highlight>
</section>

<section id="pool"><title>LDAP Connection Pool</title>

    <p>LDAP connections are pooled from request to request. This
    allows the LDAP server to remain connected and bound ready for
    the next request, without the need to unbind/connect/rebind.
    The performance advantages are similar to the effect of HTTP
    keepalives.</p>

    <p>On a busy server it is possible that many requests will try
    and access the same LDAP server connection simultaneously.
    Where an LDAP connection is in use, Apache will create a new
    connection alongside the original one. This ensures that the
    connection pool does not become a bottleneck.</p>

    <p>There is no need to manually enable connection pooling in
    the Apache configuration. Any module using this module for
    access to LDAP services will share the connection pool.</p>

    <p>LDAP connections can keep track of the ldap client
    credentials used when binding to an LDAP server. These
    credentials can be provided to LDAP servers that do not
    allow anonymous binds during referral chasing. To control
    this feature, see the
    <directive module="mod_ldap">LDAPReferrals</directive> and
    <directive module="mod_ldap">LDAPReferralHopLimit</directive>
    directives. By default, this feature is enabled.</p>
</section>

<section id="cache"><title>LDAP Cache</title>

    <p>For improved performance, <module>mod_ldap</module> uses an aggressive
    caching strategy to minimize the number of times that the LDAP
    server must be contacted. Caching can easily double or triple
    the throughput of Apache when it is serving pages protected
    with mod_authnz_ldap. In addition, the load on the LDAP server
    will be significantly decreased.</p>

    <p><module>mod_ldap</module> supports two types of LDAP caching during
    the search/bind phase with a <em>search/bind cache</em> and
    during the compare phase with two <em>operation
    caches</em>. Each LDAP URL that is used by the server has
    its own set of these three caches.</p>

    <section id="search-bind"><title>The Search/Bind Cache</title>
      <p>The process of doing a search and then a bind is the
      most time-consuming aspect of LDAP operation, especially if
      the directory is large. The search/bind cache is used to
      cache all searches that resulted in successful binds.
      Negative results (<em>i.e.</em>, unsuccessful searches, or searches
      that did not result in a successful bind) are not cached.
      The rationale behind this decision is that connections with
      invalid credentials are only a tiny percentage of the total
      number of connections, so by not caching invalid
      credentials, the size of the cache is reduced.</p>

      <p><module>mod_ldap</module> stores the username, the DN
      retrieved, the password used to bind, and the time of the bind
      in the cache. Whenever a new connection is initiated with the
      same username, <module>mod_ldap</module> compares the password
      of the new connection with the password in the cache. If the
      passwords match, and if the cached entry is not too old,
      <module>mod_ldap</module> bypasses the search/bind phase.</p>

      <p>The search and bind cache is controlled with the <directive
      module="mod_ldap">LDAPCacheEntries</directive> and <directive
      module="mod_ldap">LDAPCacheTTL</directive> directives.</p>
    </section>

    <section id="opcaches"><title>Operation Caches</title>
      <p>During attribute and distinguished name comparison
      functions, <module>mod_ldap</module> uses two operation caches
      to cache the compare operations. The first compare cache is
      used to cache the results of compares done to test for LDAP
      group membership. The second compare cache is used to cache
      the results of comparisons done between distinguished
      names.</p>

      <p>Note that, when group membership is being checked, any sub-group
      comparison results are cached to speed future sub-group comparisons.</p>

      <p>The behavior of both of these caches is controlled with
      the <directive module="mod_ldap">LDAPOpCacheEntries</directive>
      and <directive module="mod_ldap">LDAPOpCacheTTL</directive>
      directives.</p>
    </section>

    <section id="monitoring"><title>Monitoring the Cache</title>
      <p><module>mod_ldap</module> has a content handler that allows
      administrators to monitor the cache performance. The name of
      the content handler is <code>ldap-status</code>, so the
      following directives could be used to access the
      <module>mod_ldap</module> cache information:</p>

      <highlight language="config">
&lt;Location "/server/cache-info"&gt;
    SetHandler ldap-status
&lt;/Location&gt;
      </highlight>

      <p>By fetching the URL <code>http://servername/cache-info</code>,
      the administrator can get a status report of every cache that is used
      by <module>mod_ldap</module> cache. Note that if Apache does not
      support shared memory, then each <program>httpd</program> instance has its
      own cache, so reloading the URL will result in different
      information each time, depending on which <program>httpd</program>
      instance processes the request.</p>
    </section>
</section>

<section id="usingssltls"><title>Using SSL/TLS</title>

    <p>The ability to create an SSL and TLS connections to an LDAP server
    is defined by the directives
    <directive module="mod_ldap">LDAPTrustedGlobalCert</directive>,
    <directive module="mod_ldap">LDAPTrustedClientCert</directive>
     and <directive module="mod_ldap">LDAPTrustedMode</directive>.
    These directives specify the CA and optional client certificates to be used,
    as well as the type of encryption to be used on the connection (none, SSL or
    TLS/STARTTLS).</p>

    <highlight language="config">
# Establish an SSL LDAP connection on port 636. Requires that
# mod_ldap and mod_authnz_ldap be loaded. Change the
# "yourdomain.example.com" to match your domain.

LDAPTrustedGlobalCert CA_DER "/certs/certfile.der"

&lt;Location "/ldap-status"&gt;
    SetHandler ldap-status

    Require host yourdomain.example.com

    Satisfy any
    AuthType Basic
    AuthName "LDAP Protected"
    AuthBasicProvider ldap
    AuthLDAPURL "ldaps://127.0.0.1/dc=example,dc=com?uid?one"
    Require valid-user
&lt;/Location&gt;
    </highlight>

    <highlight language="config">
# Establish a TLS LDAP connection on port 389. Requires that
# mod_ldap and mod_authnz_ldap be loaded. Change the
# "yourdomain.example.com" to match your domain.

LDAPTrustedGlobalCert CA_DER "/certs/certfile.der"

&lt;Location "/ldap-status"&gt;
    SetHandler ldap-status

    Require host yourdomain.example.com

    Satisfy any
    AuthType Basic
    AuthName "LDAP Protected"
    AuthBasicProvider ldap
    AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=com?uid?one" TLS
    Require valid-user
&lt;/Location&gt;
    </highlight>

</section>

<section id="settingcerts"><title>SSL/TLS Certificates</title>

    <p>The different LDAP SDKs have widely different methods of setting
    and handling both CA and client side certificates.</p>

    <p>If you intend to use SSL or TLS, read this section CAREFULLY so as to
    understand the differences between configurations on the different LDAP
    toolkits supported.</p>

    <section id="settingcerts-netscape"><title>Netscape/Mozilla/iPlanet SDK</title>
        <p>CA certificates are specified within a file called cert7.db.
        The SDK will not talk to any LDAP server whose certificate was
        not signed by a CA specified in this file. If
        client certificates are required, an optional key3.db file may
        be specified with an optional password. The secmod file can be
        specified if required. These files are in the same format as
        used by the Netscape Communicator or Mozilla web browsers. The easiest
        way to obtain these files is to grab them from your browser
        installation.</p>

        <p>Client certificates are specified per connection using the
        LDAPTrustedClientCert directive by referring
        to the certificate "nickname". An optional password may be
        specified to unlock the certificate's private key.</p>

        <p>The SDK supports SSL only. An attempt to use STARTTLS will cause
        an error when an attempt is made to contact the LDAP server at
        runtime.</p>

        <highlight language="config">
# Specify a Netscape CA certificate file
LDAPTrustedGlobalCert CA_CERT7_DB "/certs/cert7.db"
# Specify an optional key3.db file for client certificate support
LDAPTrustedGlobalCert CERT_KEY3_DB "/certs/key3.db"
# Specify the secmod file if required
LDAPTrustedGlobalCert CA_SECMOD "/certs/secmod"
&lt;Location "/ldap-status"&gt;
    SetHandler ldap-status

    Require host yourdomain.example.com

    Satisfy any
    AuthType Basic
    AuthName "LDAP Protected"
    AuthBasicProvider ldap
    LDAPTrustedClientCert CERT_NICKNAME &lt;nickname&gt; [password]
    AuthLDAPURL "ldaps://127.0.0.1/dc=example,dc=com?uid?one"
    Require valid-user
&lt;/Location&gt;
        </highlight>

    </section>

    <section id="settingcerts-novell"><title>Novell SDK</title>

        <p>One or more CA certificates must be specified for the Novell
        SDK to work correctly. These certificates can be specified as
        binary DER or Base64 (PEM) encoded files.</p>

        <p>Note: Client certificates are specified globally rather than per
        connection, and so must be specified with the LDAPTrustedGlobalCert
        directive as below. Trying to set client certificates via the
        LDAPTrustedClientCert directive will cause an error to be logged
        when an attempt is made to connect to the LDAP server..</p>

        <p>The SDK supports both SSL and STARTTLS, set using the
        LDAPTrustedMode parameter. If an ldaps:// URL is specified,
        SSL mode is forced, override this directive.</p>

        <highlight language="config">
# Specify two CA certificate files
LDAPTrustedGlobalCert CA_DER "/certs/cacert1.der"
LDAPTrustedGlobalCert CA_BASE64 "/certs/cacert2.pem"
# Specify a client certificate file and key
LDAPTrustedGlobalCert CERT_BASE64 "/certs/cert1.pem"
LDAPTrustedGlobalCert KEY_BASE64 "/certs/key1.pem" [password]
# Do not use this directive, as it will throw an error
#LDAPTrustedClientCert CERT_BASE64 "/certs/cert1.pem"
        </highlight>

    </section>

    <section id="settingcerts-openldap"><title>OpenLDAP SDK</title>

        <p>One or more CA certificates must be specified for the OpenLDAP
        SDK to work correctly. These certificates can be specified as
        binary DER or Base64 (PEM) encoded files.</p>

        <p>Both CA and client certificates may be specified globally
        (LDAPTrustedGlobalCert) or per-connection (LDAPTrustedClientCert).
        When any settings are specified per-connection, the global
        settings are superseded.</p>

        <p>The documentation for the SDK claims to support both SSL and
        STARTTLS, however STARTTLS does not seem to work on all versions
        of the SDK. The SSL/TLS mode can be set using the
        LDAPTrustedMode parameter. If an ldaps:// URL is specified,
        SSL mode is forced. The OpenLDAP documentation notes that SSL
        (ldaps://) support has been deprecated to be replaced with TLS,
        although the SSL functionality still works.</p>

        <highlight language="config">
# Specify two CA certificate files
LDAPTrustedGlobalCert CA_DER "/certs/cacert1.der"
LDAPTrustedGlobalCert CA_BASE64 "/certs/cacert2.pem"
&lt;Location "/ldap-status"&gt;
    SetHandler ldap-status

    Require host yourdomain.example.com

    LDAPTrustedClientCert CERT_BASE64 "/certs/cert1.pem"
    LDAPTrustedClientCert KEY_BASE64 "/certs/key1.pem"
    # CA certs respecified due to per-directory client certs
    LDAPTrustedClientCert CA_DER "/certs/cacert1.der"
    LDAPTrustedClientCert CA_BASE64 "/certs/cacert2.pem"
    Satisfy any
    AuthType Basic
    AuthName "LDAP Protected"
    AuthBasicProvider ldap
    AuthLDAPURL "ldaps://127.0.0.1/dc=example,dc=com?uid?one"
    Require valid-user
&lt;/Location&gt;
        </highlight>

    </section>

    <section id="settingcerts-solaris"><title>Solaris SDK</title>

        <p>SSL/TLS for the native Solaris LDAP libraries is not yet
        supported. If required, install and use the OpenLDAP libraries
        instead.</p>

    </section>

    <section id="settingcerts-microsoft"><title>Microsoft SDK</title>

        <p>SSL/TLS certificate configuration for the native Microsoft
        LDAP libraries is done inside the system registry, and no
        configuration directives are required.</p>

        <p>Both SSL and TLS are supported by using the ldaps:// URL
        format, or by using the LDAPTrustedMode directive accordingly.</p>

        <p>Note: The status of support for client certificates is not yet known
        for this toolkit.</p>

    </section>

</section>

<directivesynopsis>
<name>LDAPSharedCacheSize</name>
<description>Size in bytes of the shared-memory cache</description>
<syntax>LDAPSharedCacheSize <var>bytes</var></syntax>
<default>LDAPSharedCacheSize 500000</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Specifies the number of bytes to allocate for the shared
    memory cache. The default is 500kb. If set to 0, shared memory
    caching will not be used and every HTTPD process will create its
    own cache.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPSharedCacheFile</name>
<description>Sets the shared memory cache file</description>
<syntax>LDAPSharedCacheFile <var>directory-path/filename</var></syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Specifies the directory path and file name of the shared memory
    cache file. If not set, anonymous shared memory will be used if the
    platform supports it.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPCacheEntries</name>
<description>Maximum number of entries in the primary LDAP cache</description>
<syntax>LDAPCacheEntries <var>number</var></syntax>
<default>LDAPCacheEntries 1024</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Specifies the maximum size of the primary LDAP cache. This
    cache contains successful search/binds. Set it to 0 to turn off
    search/bind caching. The default size is 1024 cached
    searches.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPCacheTTL</name>
<description>Time that cached items remain valid</description>
<syntax>LDAPCacheTTL <var>seconds</var></syntax>
<default>LDAPCacheTTL 600</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Specifies the time (in seconds) that an item in the
    search/bind cache remains valid. The default is 600 seconds (10
    minutes).</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPOpCacheEntries</name>
<description>Number of entries used to cache LDAP compare
operations</description>
<syntax>LDAPOpCacheEntries <var>number</var></syntax>
<default>LDAPOpCacheEntries 1024</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>This specifies the number of entries <module>mod_ldap</module>
    will use to cache LDAP compare operations. The default is 1024
    entries.  Setting it to 0 disables operation caching.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPOpCacheTTL</name>
<description>Time that entries in the operation cache remain
valid</description>
<syntax>LDAPOpCacheTTL <var>seconds</var></syntax>
<default>LDAPOpCacheTTL 600</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Specifies the time (in seconds) that entries in the
    operation cache remain valid. The default is 600 seconds.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPReferralHopLimit</name>
<description>The maximum number of referral hops to chase before terminating an LDAP query.</description>
<syntax>LDAPReferralHopLimit <var>number</var></syntax>
<default>SDK dependent, typically between 5 and 10</default>
<contextlist><context>directory</context><context>.htaccess</context></contextlist>
<override>AuthConfig</override>

<usage>
    <p>This directive, if enabled by the <directive>LDAPReferrals</directive> directive,
    limits the number of referral hops that are followed before terminating an
    LDAP query.</p>

<note type="warning">
<p> Support for this tunable is uncommon in LDAP SDKs.</p>
</note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPReferrals</name>
<description>Enable referral chasing during queries to the LDAP server.</description>
<syntax>LDAPReferrals <var>On|Off|default</var></syntax>
<default>LDAPReferrals On</default>
<contextlist><context>directory</context><context>.htaccess</context></contextlist>
<override>AuthConfig</override>
<compatibility>The <var>default</var> parameter is available in Apache 2.4.7 and later</compatibility>

<usage>
    <p>Some LDAP servers divide their directory among multiple domains and use referrals
    to direct a client when a domain boundary is crossed. This is similar to a HTTP redirect.
    LDAP client libraries may or may not chase referrals by default. This directive
    explicitly configures the referral chasing in the underlying SDK.</p>


    <p><directive>LDAPReferrals</directive> takes the following values:</p>
    <dl>
     <dt>"on"</dt>
     <dd> <p> When set to "on", the underlying SDK's referral chasing state
              is enabled, <directive>LDAPReferralHopLimit</directive> is used to
              override the SDK's hop limit, and an LDAP rebind callback is
              registered.</p></dd>
     <dt>"off"</dt>
     <dd> <p> When set to "off", the underlying SDK's referral chasing state
              is disabled completely.</p></dd>
     <dt>"default"</dt>
     <dd> <p> When set to "default", the underlying SDK's referral chasing state
              is not changed, <directive>LDAPReferralHopLimit</directive> is not
              used to overide the SDK's hop limit, and no LDAP rebind callback is
              registered.</p></dd>
    </dl>

    <p>The directive <directive>LDAPReferralHopLimit</directive> works in conjunction with
    this directive to limit the number of referral hops to follow before terminating the LDAP query.
    When referral processing is enabled by a value of "On", client credentials will be provided,
    via a rebind callback, for any LDAP server requiring them.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPRetryDelay</name>
<description>Configures the delay between LDAP server retries.</description>
<syntax>LDAPRetryDelay <var>seconds</var></syntax>
<default>LDAPRetryDelay 0</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>If <directive>LDAPRetryDelay</directive> is set to a non-zero
    value, the server will delay retrying an LDAP request for the
    specified amount of time.  Setting this directive to 0 will
    result in any retry to occur without delay.</p>

    <p>LDAP errors such as timeouts and refused connections are retryable.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPRetries</name>
<description>Configures the number of LDAP server retries.</description>
<syntax>LDAPRetries <var>number-of-retries</var></syntax>
<default>LDAPRetries 3</default>
<contextlist><context>server config</context></contextlist>
<usage>
    <p>The server will retry failed LDAP requests up to
    <directive>LDAPRetries</directive> times.  Setting this
    directive to 0 disables retries.</p>
    <p>LDAP errors such as timeouts and refused connections are retryable.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPTrustedGlobalCert</name>
<description>Sets the file or database containing global trusted
Certificate Authority or global client certificates</description>
<syntax>LDAPTrustedGlobalCert <var>type</var> <var>directory-path/filename</var> <var>[password]</var></syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>It specifies the directory path and file name of the trusted CA
    certificates and/or system wide client certificates <module>mod_ldap</module>
    should use when establishing an SSL or TLS connection to an LDAP
    server. Note that all certificate information specified using this directive
    is applied globally to the entire server installation. Some LDAP toolkits
    (notably Novell) require all client certificates to be set globally using
    this directive. Most other toolkits require clients certificates to be set
    per Directory or per Location using LDAPTrustedClientCert. If you get this
    wrong, an error may be logged when an attempt is made to contact the LDAP
    server, or the connection may silently fail (See the SSL/TLS certificate
    guide above for details).
    The type specifies the kind of certificate parameter being
    set, depending on the LDAP toolkit being used. Supported types are:</p>
    <ul>
      <li>CA_DER - binary DER encoded CA certificate</li>
      <li>CA_BASE64 - PEM encoded CA certificate</li>
      <li>CA_CERT7_DB - Netscape cert7.db CA certificate database file</li>
      <li>CA_SECMOD - Netscape secmod database file</li>
      <li>CERT_DER - binary DER encoded client certificate</li>
      <li>CERT_BASE64 - PEM encoded client certificate</li>
      <li>CERT_KEY3_DB - Netscape key3.db client certificate database file</li>
      <li>CERT_NICKNAME - Client certificate "nickname" (Netscape SDK)</li>
      <li>CERT_PFX - PKCS#12 encoded client certificate (Novell SDK)</li>
      <li>KEY_DER - binary DER encoded private key</li>
      <li>KEY_BASE64 - PEM encoded private key</li>
      <li>KEY_PFX - PKCS#12 encoded private key (Novell SDK)</li>
    </ul>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPTrustedClientCert</name>
<description>Sets the file containing or nickname referring to a per
connection client certificate. Not all LDAP toolkits support per
connection client certificates.</description>
<syntax>LDAPTrustedClientCert <var>type</var> <var>directory-path/filename/nickname</var> <var>[password]</var></syntax>
<contextlist><context>directory</context><context>.htaccess</context></contextlist>

<usage>
    <p>It specifies the directory path, file name or nickname of a
    per connection client certificate used when establishing an SSL
    or TLS connection to an LDAP server. Different locations or
    directories may have their own independent client certificate
    settings. Some LDAP toolkits (notably Novell)
    do not support per connection client certificates, and will throw an
    error on LDAP server connection if you try to use this directive
    (Use the LDAPTrustedGlobalCert directive instead for Novell client
    certificates - See the SSL/TLS certificate guide above for details).
    The type specifies the kind of certificate parameter being
    set, depending on the LDAP toolkit being used. Supported types are:</p>
    <ul>
      <li>CA_DER - binary DER encoded CA certificate</li>
      <li>CA_BASE64 - PEM encoded CA certificate</li>
      <li>CERT_DER - binary DER encoded client certificate</li>
      <li>CERT_BASE64 - PEM encoded client certificate</li>
      <li>CERT_NICKNAME - Client certificate "nickname" (Netscape SDK)</li>
      <li>KEY_DER - binary DER encoded private key</li>
      <li>KEY_BASE64 - PEM encoded private key</li>
    </ul>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPTrustedMode</name>
<description>Specifies the SSL/TLS mode to be used when connecting to an LDAP server.</description>
<syntax>LDAPTrustedMode <var>type</var></syntax>
<contextlist><context>server config</context><context>virtual host</context></contextlist>

<usage>
    <p>The following modes are supported:</p>
    <ul>
      <li>NONE - no encryption</li>
      <li>SSL - ldaps:// encryption on default port 636</li>
      <li>TLS - STARTTLS encryption on default port 389</li>
    </ul>

    <p>Not all LDAP toolkits support all the above modes. An error message
    will be logged at runtime if a mode is not supported, and the
    connection to the LDAP server will fail.
    </p>

    <p>If an ldaps:// URL is specified, the mode becomes SSL and the setting
    of LDAPTrustedMode is ignored.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPConnectionTimeout</name>
<description>Specifies the socket connection timeout in seconds</description>
<syntax>LDAPConnectionTimeout <var>seconds</var></syntax>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>This directive configures the LDAP_OPT_NETWORK_TIMEOUT (or LDAP_OPT_CONNECT_TIMEOUT)
    option in the underlying LDAP client library, when available.  This value
    typically controls how long the LDAP client library will wait for the TCP
    connection to the LDAP server to complete.</p>

    <p> If a connection is not successful with the timeout period, either an error will be
    returned or the LDAP client library will attempt to connect to a secondary LDAP
    server if one is specified (via a space-separated list of hostnames in the
    <directive module="mod_authnz_ldap">AuthLDAPURL</directive>).</p>

    <p>The default is 10 seconds, if the LDAP client library linked with the
    server supports the LDAP_OPT_NETWORK_TIMEOUT option.</p>

    <note>LDAPConnectionTimeout is only available when the LDAP client library linked
    with the server supports the LDAP_OPT_NETWORK_TIMEOUT
    (or LDAP_OPT_CONNECT_TIMEOUT) option, and the ultimate behavior is
    dictated entirely by the LDAP client library.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LDAPTimeout</name>
<description>Specifies the timeout for LDAP search and bind operations, in seconds</description>
<syntax>LDAPTimeout <var>seconds</var></syntax>
<default>LDAPTimeout 60</default>
<contextlist><context>server config</context></contextlist>
<compatibility>Apache HTTP Server 2.3.5 and later</compatibility>

<usage>
    <p>This directive configures the timeout for bind and search operations, as well as
    the LDAP_OPT_TIMEOUT option in the underlying LDAP client library, when available.</p>

    <p> If the timeout expires, httpd will retry in case an existing connection has
    been silently dropped by a firewall. However, performance will be much better if
    the firewall is configured to send TCP RST packets instead of silently dropping
    packets.</p>

    <note>
    <p>Timeouts for ldap compare operations requires an SDK with LDAP_OPT_TIMEOUT, such as OpenLDAP &gt;= 2.4.4.</p>
    </note>

</usage>
</directivesynopsis>


<directivesynopsis>
<name>LDAPVerifyServerCert</name>
<description>Force server certificate verification</description>
<syntax>LDAPVerifyServerCert <var>On|Off</var></syntax>
<default>LDAPVerifyServerCert On</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Specifies whether to force the verification of a
    server certificate when establishing an SSL connection to the
    LDAP server.</p>
</usage>
</directivesynopsis>


<directivesynopsis>
<name>LDAPConnectionPoolTTL</name>
<description>Discard backend connections that have been sitting in the connection pool too long</description>
<syntax>LDAPConnectionPoolTTL <var>n</var></syntax>
<default>LDAPConnectionPoolTTL -1</default>
<contextlist><context>server config</context><context>virtual host</context></contextlist>
<compatibility>Apache HTTP Server 2.3.12 and later</compatibility>

<usage>
    <p>Specifies the maximum age, in seconds, that a pooled LDAP connection can remain idle
    and still be available for use.  Connections are cleaned up when they are next needed,
    not asynchronously.</p>

    <p>A setting of 0 causes connections to never be saved in the backend
    connection pool.  The default value of -1, and any other negative value,
    allows connections of any age to be reused.</p>

    <p>For performance reasons, the reference time used by this directive is
    based on when the LDAP connection is returned to the pool, not the time
    of the last successful I/O with the LDAP server.  </p>

    <p>Since 2.4.10, new measures are in place to avoid the reference time
    from being inflated by cache hits or slow requests.  First, the reference
    time is not updated if no backend LDAP conncetions were needed. Second,
    the reference time uses the time the HTTP request was received instead
    of the time the request is completed.</p>

    <note><p>This timeout defaults to units of seconds, but accepts
    suffixes for milliseconds (ms), minutes (min), and hours (h).
    </p></note>
</usage>
</directivesynopsis>


<directivesynopsis>
<name>LDAPLibraryDebug</name>
<description>Enable debugging in the LDAP SDK</description>
<syntax>LDAPLibraryDebug <var>7</var></syntax>
<default>disabled</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p>Turns on SDK-specific LDAP debug options that generally cause the LDAP
    SDK to log verbose trace information to the main Apache error log.
    The trace messages from the LDAP SDK provide gory details that
    can be useful during debugging of connectivity problems with backend LDAP servers</p>

    <p>This option is only configurable when Apache HTTP Server is linked with
    an LDAP SDK that implements <code>LDAP_OPT_DEBUG</code> or
    <code>LDAP_OPT_DEBUG_LEVEL</code>, such as OpenLDAP (a value of 7 is verbose)
    or Tivoli Directory Server (a value of 65535 is verbose).</p>

    <note type="warning">
    <p>The logged information will likely contain plaintext credentials being used or
    validated by LDAP authentication, so care should be taken in protecting and purging
    the error log when this directive is used.</p>
    </note>

</usage>
</directivesynopsis>


</modulesynopsis>
