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439 lines
19 KiB
XML
<?xml version='1.0' encoding='UTF-8' ?>
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<!DOCTYPE manualpage SYSTEM "./style/manualpage.dtd">
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<?xml-stylesheet type="text/xsl" href="./style/manual.en.xsl"?>
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<!-- $LastChangedRevision$ -->
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<!--
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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<manualpage metafile="new_features_2_4.xml.meta">
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<title>Overview of new features in Apache HTTP Server 2.4</title>
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<summary>
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<p>This document describes some of the major changes between the
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2.2 and 2.4 versions of the Apache HTTP Server. For new features since
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version 2.0, see the <a href="new_features_2_2.html">2.2 new features</a>
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document.</p>
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</summary>
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<section id="core">
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<title>Core Enhancements</title>
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<dl>
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<dt>Run-time Loadable MPMs</dt>
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<dd>Multiple MPMs can now be <a href="mpm.html#dynamic">built
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as loadable modules</a> at compile time.
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The MPM of choice can be configured at run time via <directive
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module="mod_so">LoadModule</directive> directive.</dd>
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<dt>Event MPM</dt>
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<dd>The <a href="mod/event.html">Event MPM</a> is no longer experimental
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but is now fully supported.</dd>
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<dt>Asynchronous support</dt>
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<dd>Better support for asynchronous read/write for supporting MPMs and
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platforms.</dd>
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<dt>Per-module and per-directory LogLevel configuration</dt>
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<dd>The <directive module="core">LogLevel</directive> can now be
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configured per module and per directory. New levels <code>trace1</code>
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to <code>trace8</code> have been added above the <code>debug</code> log
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level.</dd>
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<dt>Per-request configuration sections</dt>
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<dd><directive module="core" type="section">If</directive>,
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<directive module="core" type="section">ElseIf</directive>,
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and <directive module="core" type="section">Else</directive>
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sections can be used to set the configuration based on per-request
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criteria.</dd>
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<dt>General-purpose expression parser</dt>
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<dd>A new expression parser allows to specify
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<a href="expr.html">complex conditions</a> using a common syntax
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in directives like
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<directive module="mod_setenvif">SetEnvIfExpr</directive>,
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<directive module="mod_rewrite">RewriteCond</directive>,
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<directive module="mod_headers">Header</directive>,
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<directive module="core" type="section">If</directive>,
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and others.
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</dd>
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<dt>KeepAliveTimeout in milliseconds</dt>
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<dd>It is now possible to specify <directive module="core"
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>KeepAliveTimeout</directive> in milliseconds.
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</dd>
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<dt>NameVirtualHost directive</dt>
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<dd>No longer needed and is now deprecated.</dd>
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<dt>Override Configuration</dt>
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<dd>The new <directive module="core">AllowOverrideList</directive>
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directive allows more fine grained control which directives are
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allowed in <code>.htaccess</code> files. </dd>
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<dt>Config file variables</dt>
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<dd>It is now possible to <directive module="core">Define</directive>
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variables in the configuration, allowing a clearer representation
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if the same value is used at many places in the configuration.
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</dd>
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<dt>Reduced memory usage</dt>
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<dd>Despite many new features, 2.4.x tends to use less memory than
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2.2.x.</dd>
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</dl>
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</section>
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<section id="newmods">
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<title>New Modules</title>
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<dl>
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<dt><module>mod_proxy_fcgi</module></dt>
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<dd>FastCGI Protocol backend for <module>mod_proxy</module></dd>
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<dt><module>mod_proxy_scgi</module></dt>
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<dd>SCGI Protocol backend for <module>mod_proxy</module></dd>
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<dt><module>mod_proxy_express</module></dt>
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<dd>Provides dynamically configured mass reverse proxies for
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<module>mod_proxy</module></dd>
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<dt><module>mod_remoteip</module></dt>
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<dd>Replaces the apparent client remote IP address and hostname for the request
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with the IP address list presented by a proxies or a load balancer via
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the request headers.</dd>
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<dt><module>mod_heartmonitor</module>,
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<module>mod_lbmethod_heartbeat</module></dt>
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<dd>Allow <module>mod_proxy_balancer</module> to base loadbalancing decisions
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on the number of active connections on the backend servers.</dd>
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<dt><module>mod_proxy_html</module></dt>
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<dd>Formerly a third-party module, this supports fixing of HTML
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links in a reverse proxy situation, where the backend generates
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URLs that are not valid for the proxy's clients.</dd>
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<dt><module>mod_sed</module></dt>
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<dd>An advanced replacement of <module>mod_substitute</module>, allows
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to edit the response body with the full power of sed.</dd>
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<dt><module>mod_auth_form</module></dt>
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<dd>Enables form-based authentication.</dd>
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<dt><module>mod_session</module></dt>
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<dd>Enables the use of session state for clients, using cookie or
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database storage.</dd>
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<dt><module>mod_allowmethods</module></dt>
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<dd>New module to restrict certain HTTP methods without interfering with
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authentication or authorization.</dd>
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<dt><module>mod_lua</module></dt>
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<dd>Embeds the <a href="http://www.lua.org/">Lua</a> language into httpd,
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for configuration and small business logic functions. (Experimental)</dd>
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<dt><module>mod_log_debug</module></dt>
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<dd>Allows the addition of customizable debug logging at different phases of the
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request processing.</dd>
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<dt><module>mod_buffer</module></dt>
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<dd>Provides for buffering the input and output filter stacks</dd>
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<dt><module>mod_data</module></dt>
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<dd>Convert response body into an RFC2397 data URL</dd>
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<dt><module>mod_ratelimit</module></dt>
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<dd>Provides Bandwidth Rate Limiting for Clients</dd>
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<dt><module>mod_request</module></dt>
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<dd>Provides Filters to handle and make available HTTP request bodies</dd>
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<dt><module>mod_reflector</module></dt>
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<dd>Provides Reflection of a request body as a response via the output filter stack.</dd>
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<dt><module>mod_slotmem_shm</module></dt>
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<dd>Provides a Slot-based shared memory provider (ala the scoreboard).</dd>
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<dt><module>mod_xml2enc</module></dt>
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<dd>Formerly a third-party module, this supports internationalisation
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in libxml2-based (markup-aware) filter modules.</dd>
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<dt><module>mod_macro</module> (available since 2.4.5)</dt>
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<dd>Provide macros within configuration files.</dd>
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<dt><module>mod_proxy_wstunnel</module> (available since 2.4.5)</dt>
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<dd>Support web-socket tunnels.</dd>
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<dt><module>mod_authnz_fcgi</module> (available since 2.4.10)</dt>
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<dd>Enable FastCGI authorizer applications to authenticate and/or
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authorize clients.</dd>
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<dt><module>mod_http2</module> (available since 2.4.17)</dt>
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<dd>Support for the HTTP/2 transport layer.</dd>
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<dt><module>mod_proxy_http2</module> (available since 2.4.19)</dt>
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<dd>HTTP/2 Protocol backend for <module>mod_proxy</module></dd>
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<dt><module>mod_proxy_hcheck</module> (available since 2.4.21)</dt>
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<dd>Support independent dynamic health checks for remote proxiy backend servers.</dd>
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<dt><module>mod_brotli</module> (available since 2.4.26)</dt>
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<dd>Support the Brotli compression algorithm.</dd>
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<dt><module>mod_md</module> (available since 2.4.30)</dt>
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<dd>Support the ACME protocol to automate certificate provisionning.</dd>
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<dt><module>mod_socache_redis</module> (available since 2.4.39)</dt>
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<dd>Support <a href="http://redis.io/">Redis</a> based shared object cache provider.</dd>
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<dt><module>mod_systemd</module> (available since 2.4.42)</dt>
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<dd>systemd integration. It allows httpd to be used in a service with the systemd
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<code>Type=notify</code>.</dd>
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</dl>
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</section>
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<section id="module">
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<title>Module Enhancements</title>
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<dl>
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<dt><module>mod_ssl</module></dt>
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<dd><module>mod_ssl</module> can now be configured to use an
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OCSP server to check the validation status of a client
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certificate. The default responder is configurable, along with
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the decision on whether to prefer the responder designated in
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the client certificate itself.</dd>
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<dd><module>mod_ssl</module> now also supports OCSP stapling, where the
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server pro-actively obtains an OCSP verification of its certificate and
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transmits that to the client during the handshake. </dd>
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<dd><module>mod_ssl</module> can now be configured to share SSL Session
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data between servers through memcached</dd>
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<dd>EC keys are now supported in addition to RSA and DSA.</dd>
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<dd>Support for TLS-SRP (available in 2.4.4 and later).</dd>
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<dt><module>mod_proxy</module></dt>
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<dd>The <directive module="mod_proxy">ProxyPass</directive> directive
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is now most optimally configured within a
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<directive module="core">Location</directive> or
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<directive module="core">LocationMatch</directive>
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block, and offers a significant performance advantage over the traditional
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two-parameter syntax when present in large numbers.</dd>
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<dd>The source address used for proxy requests is now configurable.</dd>
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<dd>Support for Unix domain sockets to the backend (available in 2.4.7
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and later).</dd>
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<dt><module>mod_proxy_balancer</module></dt>
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<dd>More runtime configuration changes for BalancerMembers via balancer-manager</dd>
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<dd>Additional BalancerMembers can be added at runtime via balancer-manager</dd>
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<dd>Runtime configuration of a subset of Balancer parameters</dd>
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<dd>BalancerMembers can be set to 'Drain' so that they only respond to existing sticky
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sessions, allowing them to be taken gracefully offline.</dd>
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<dd>Balancer settings can be persistent after restarts.</dd>
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<dt><module>mod_cache</module></dt>
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<dd>The <module>mod_cache</module> CACHE filter can be optionally inserted
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at a given point in the filter chain to provide fine control over caching.
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</dd>
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<dd><module>mod_cache</module> can now cache HEAD requests.</dd>
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<dd>Where possible, <module>mod_cache</module> directives can now be set
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per directory, instead of per server.</dd>
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<dd>The base URL of cached URLs can be customised, so that a cluster of
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caches can share the same endpoint URL prefix.</dd>
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<dd><module>mod_cache</module> is now capable of serving stale cached
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data when a backend is unavailable (error 5xx).</dd>
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<dd><module>mod_cache</module> can now insert HIT/MISS/REVALIDATE into
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an X-Cache header.</dd>
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<dt><module>mod_include</module></dt>
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<dd>Support for the 'onerror' attribute within an 'include' element,
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allowing an error document to be served on error instead of the default
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error string.</dd>
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<dt><module>mod_cgi</module>, <module>mod_include</module>,
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<module>mod_isapi</module>, ...</dt>
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<dd>Translation of headers to environment variables is more strict than
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before to mitigate some possible cross-site-scripting attacks via header
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injection. Header names containing invalid characters (including underscores)
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are no longer converted to environment variables. <a href="env.html">Environment Variables
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in Apache</a> has some pointers on how to work around broken legacy
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clients which require such headers. (This affects all modules which
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use these environment variables.)</dd>
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<dt><module>mod_authz_core</module> Authorization Logic Containers</dt>
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<dd>Advanced authorization logic may now be specified using the
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<directive module="mod_authz_core">Require</directive> directive
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and the related container directives, such as
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<directive module="mod_authz_core"
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type="section">RequireAll</directive>.</dd>
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<dt><module>mod_rewrite</module></dt>
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<dd><module>mod_rewrite</module> adds the <code>[QSD]</code>
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(Query String Discard) and <code>[END]</code> flags for
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<directive module="mod_rewrite">RewriteRule</directive> to
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simplify common rewriting scenarios.</dd>
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<dd>Adds the possibility to use complex boolean expressions in <directive
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module="mod_rewrite">RewriteCond</directive>.</dd>
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<dd>Allows the use of SQL queries as <directive
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module="mod_rewrite">RewriteMap</directive> functions.</dd>
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<dt><module>mod_ldap</module>, <module>mod_authnz_ldap</module></dt>
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<dd><module>mod_authnz_ldap</module> adds support for nested groups.</dd>
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<dd><module>mod_ldap</module> adds
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<directive module="mod_ldap">LDAPConnectionPoolTTL</directive>,
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<directive module="mod_ldap">LDAPTimeout</directive>, and
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other improvements in the handling of timeouts.
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This is especially useful for setups where a
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stateful firewall drops idle connections to the LDAP server.</dd>
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<dd><module>mod_ldap</module> adds
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<directive module="mod_ldap">LDAPLibraryDebug</directive> to log
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debug information provided by the used LDAP toolkit.</dd>
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<dt><module>mod_info</module></dt>
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<dd><module>mod_info</module> can now dump the pre-parsed configuration
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to stdout during server startup.</dd>
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<dt><module>mod_auth_basic</module></dt>
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<dd>New generic mechanism to fake basic authentication (available in
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2.4.5 and later).</dd>
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</dl>
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</section>
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<section id="programs">
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<title>Program Enhancements</title>
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<dl>
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<dt><program>fcgistarter</program></dt>
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<dd>New FastCGI daemon starter utility</dd>
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<dt><program>htcacheclean</program></dt>
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<dd>Current cached URLs can now be listed, with optional metadata
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included.</dd>
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<dd>Allow explicit deletion of individual cached URLs from the
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cache.</dd>
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<dd>File sizes can now be rounded up to the given block size, making
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the size limits map more closely to the real size on disk.</dd>
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<dd>Cache size can now be limited by the number of inodes, instead
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of or in addition to being limited by the size of the files on
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disk.</dd>
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<dt><program>rotatelogs</program></dt>
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<dd>May now create a link to the current log file.</dd>
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<dd>May now invoke a custom post-rotate script.</dd>
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<dt><program>htpasswd</program>, <program>htdbm</program></dt>
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<dd>Support for the bcrypt algorithm (available in 2.4.4 and later).
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</dd>
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</dl>
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</section>
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<section id="documentation">
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<title>Documentation</title>
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<dl>
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<dt>mod_rewrite</dt>
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<dd>The <module>mod_rewrite</module> documentation has been
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rearranged and almost completely rewritten, with a focus on
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examples and common usage, as well as on showing you when other
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solutions are more appropriate. The <a href="rewrite/">Rewrite
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Guide</a> is now a top-level section with much more detail and
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better organization.</dd>
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<dt>mod_ssl</dt>
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<dd>The <module>mod_ssl</module> documentation has been greatly
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enhanced, with more examples at the getting started level, in
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addition to the previous focus on technical details.</dd>
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<dt>Caching Guide</dt>
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<dd>The <a href="caching.html">Caching Guide</a> has been rewritten
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to properly distinguish between the RFC2616 HTTP/1.1 caching
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features provided by <module>mod_cache</module>, and the generic
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key/value caching provided by the <a href="socache.html">socache</a>
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interface, as well as to cover specialised caching provided by
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mechanisms such as <module>mod_file_cache</module>.</dd>
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</dl>
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</section>
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<section id="developer">
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<title>Module Developer Changes</title>
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<dl>
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<dt>Check Configuration Hook Added</dt>
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<dd>A new hook, <code>check_config</code>, has been added which runs
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between the <code>pre_config</code> and <code>open_logs</code>
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hooks. It also runs before the <code>test_config</code> hook
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when the <code>-t</code> option is passed to
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<program>httpd</program>. The <code>check_config</code> hook
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allows modules to review interdependent configuration directive
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values and adjust them while messages can still be logged to the
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console. The user can thus be alerted to misconfiguration problems
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before the core <code>open_logs</code> hook function redirects
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console output to the error log.</dd>
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<dt>Expression Parser Added</dt>
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<dd>We now have a general-purpose expression parser, whose API is
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exposed in <var>ap_expr.h</var>. This is adapted from the
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expression parser previously implemented in
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<module>mod_ssl</module>.</dd>
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<dt>Authorization Logic Containers</dt>
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<dd>Authorization modules now register as a provider, via
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ap_register_auth_provider(), to support advanced authorization logic,
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such as <directive module="mod_authz_core" type="section"
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>RequireAll</directive>.</dd>
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<dt>Small-Object Caching Interface</dt>
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<dd>The <var>ap_socache.h</var> header exposes a provider-based
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interface for caching small data objects, based on the previous
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implementation of the <module>mod_ssl</module> session cache.
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Providers using a shared-memory cyclic buffer, disk-based dbm
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files, and a memcache distributed cache are currently
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supported.</dd>
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<dt>Cache Status Hook Added</dt>
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<dd>The <module>mod_cache</module> module now includes a new
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<code>cache_status</code> hook, which is called when the caching
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decision becomes known. A default implementation is provided
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which adds an optional <code>X-Cache</code> and
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<code>X-Cache-Detail</code> header to the response.</dd>
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</dl>
|
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<p>The developer documentation contains a
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<a href="developer/new_api_2_4.html">detailed list of API changes</a>.</p>
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</section>
|
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|
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</manualpage>
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