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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:01:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:01:30 +0000
commit6beeb1b708550be0d4a53b272283e17e5e35fe17 (patch)
tree1ce8673d4aaa948e5554000101f46536a1e4cc29 /docs/manual/rewrite/access.html.en
parentInitial commit. (diff)
downloadapache2-6beeb1b708550be0d4a53b272283e17e5e35fe17.tar.xz
apache2-6beeb1b708550be0d4a53b272283e17e5e35fe17.zip
Adding upstream version 2.4.57.upstream/2.4.57upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
+<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
+<!--
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ This file is generated from xml source: DO NOT EDIT
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ -->
+<title>Using mod_rewrite to control access - Apache HTTP Server Version 2.4</title>
+<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
+<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
+<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
+<script src="../style/scripts/prettify.min.js" type="text/javascript">
+</script>
+
+<link href="../images/favicon.ico" rel="shortcut icon" /></head>
+<body id="manual-page"><div id="page-header">
+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.4</p>
+<img alt="" src="../images/feather.png" /></div>
+<div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.4</a> &gt; <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>Using mod_rewrite to control access</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="../en/rewrite/access.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../fr/rewrite/access.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
+</div>
+
+
+<p>This document supplements the <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
+<a href="../mod/mod_rewrite.html">reference documentation</a>. It describes
+how you can use <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to control access to
+various resources, and other related techniques.
+This includes many examples of common uses of mod_rewrite,
+including detailed descriptions of how each works.</p>
+
+<div class="warning">Note that many of these examples won't work unchanged in your
+particular server configuration, so it's important that you understand
+them, rather than merely cutting and pasting the examples into your
+configuration.</div>
+
+</div>
+<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#blocked-inline-images">Forbidding Image "Hotlinking"</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#blocking-of-robots">Blocking of Robots</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#host-deny">Denying Hosts in a Reject List</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#referer-deflector">Referer-based Deflector</a></li>
+</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="rewritemap.html">Using RewriteMap</a></li><li><a href="advanced.html">Advanced techniques</a></li><li><a href="avoid.html">When not to use mod_rewrite</a></li><li><a href="#comments_section">Comments</a></li></ul></div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="blocked-inline-images" id="blocked-inline-images">Forbidding Image "Hotlinking"</a></h2>
+
+
+
+ <dl>
+ <dt>Description:</dt>
+
+ <dd>
+ <p>The following technique forbids the practice of other sites
+ including your images inline in their pages. This practice is
+ often referred to as "hotlinking", and results in
+ your bandwidth being used to serve content for someone else's
+ site.</p>
+ </dd>
+
+ <dt>Solution:</dt>
+
+ <dd>
+ <p>This technique relies on the value of the
+ <code>HTTP_REFERER</code> variable, which is optional. As
+ such, it's possible for some people to circumvent this
+ limitation. However, most users will experience the failed
+ request, which should, over time, result in the image being
+ removed from that other site.</p>
+ <p>There are several ways that you can handle this
+ situation.</p>
+
+ <p>In this first example, we simply deny the request, if it didn't
+ initiate from a page on our site. For the purpose of this example,
+ we assume that our site is <code>www.example.com</code>.</p>
+
+
+
+<pre class="prettyprint lang-config">RewriteCond "%{HTTP_REFERER}" "!^$"
+RewriteCond "%{HTTP_REFERER}" "!www.example.com" [NC]
+RewriteRule "\.(gif|jpg|png)$" "-" [F,NC]</pre>
+
+
+ <p>In this second example, instead of failing the request, we display
+ an alternate image instead.</p>
+
+<pre class="prettyprint lang-config">RewriteCond "%{HTTP_REFERER}" "!^$"
+RewriteCond "%{HTTP_REFERER}" "!www.example.com" [NC]
+RewriteRule "\.(gif|jpg|png)$" "/images/go-away.png" [R,NC]</pre>
+
+
+ <p>In the third example, we redirect the request to an image on some
+ other site.</p>
+
+<pre class="prettyprint lang-config">RewriteCond "%{HTTP_REFERER}" "!^$"
+RewriteCond "%{HTTP_REFERER}" "!www.example.com" [NC]
+RewriteRule "\.(gif|jpg|png)$" "http://other.example.com/image.gif" [R,NC]</pre>
+
+
+ <p>Of these techniques, the last two tend to be the most effective
+ in getting people to stop hotlinking your images, because they will
+ simply not see the image that they expected to see.</p>
+
+ </dd>
+
+ <dt>Discussion:</dt>
+
+ <dd>
+ <p>If all you wish to do is deny access to the resource, rather
+ than redirecting that request elsewhere, this can be
+ accomplished without the use of mod_rewrite:</p>
+
+ <pre class="prettyprint lang-config">SetEnvIf Referer "example\.com" localreferer
+&lt;FilesMatch "\.(jpg|png|gif)$"&gt;
+ Require env localreferer
+&lt;/FilesMatch&gt;</pre>
+
+ </dd>
+ </dl>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="blocking-of-robots" id="blocking-of-robots">Blocking of Robots</a></h2>
+
+
+
+ <dl>
+ <dt>Description:</dt>
+
+ <dd>
+ <p>
+ In this recipe, we discuss how to block persistent requests from
+ a particular robot, or user agent.</p>
+
+ <p>The standard for robot exclusion defines a file,
+ <code>/robots.txt</code> that specifies those portions of your
+ website where you wish to exclude robots. However, some robots
+ do not honor these files.
+ </p>
+
+ <p>Note that there are methods of accomplishing this which do
+ not use mod_rewrite. Note also that any technique that relies on
+ the clients <code>USER_AGENT</code> string can be circumvented
+ very easily, since that string can be changed.</p>
+ </dd>
+
+ <dt>Solution:</dt>
+
+ <dd>
+ <p>We use a ruleset that specifies the directory to be
+ protected, and the client <code>USER_AGENT</code> that
+ identifies the malicious or persistent robot.</p>
+
+ <p>In this example, we are blocking a robot called
+ <code>NameOfBadRobot</code> from a location
+ <code>/secret/files</code>. You may also specify an IP address
+ range, if you are trying to block that user agent only from the
+ particular source.</p>
+
+<pre class="prettyprint lang-config">RewriteCond "%{HTTP_USER_AGENT}" "^NameOfBadRobot"
+RewriteCond "%{REMOTE_ADDR}" "=123\.45\.67\.[8-9]"
+RewriteRule "^/secret/files/" "-" [F]</pre>
+
+ </dd>
+
+ <dt>Discussion:</dt>
+
+ <dd>
+ <p>
+ Rather than using mod_rewrite for this, you can accomplish the
+ same end using alternate means, as illustrated here:
+ </p>
+ <pre class="prettyprint lang-config">SetEnvIfNoCase User-Agent "^NameOfBadRobot" goaway
+&lt;Location "/secret/files"&gt;
+ &lt;RequireAll&gt;
+ Require all granted
+ Require not env goaway
+ &lt;/RequireAll&gt;
+&lt;/Location&gt;</pre>
+
+ <p>
+ As noted above, this technique is trivial to circumvent, by simply
+ modifying the <code>USER_AGENT</code> request header. If you
+ are experiencing a sustained attack, you should consider blocking
+ it at a higher level, such as at your firewall.
+ </p>
+
+ </dd>
+
+ </dl>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="host-deny" id="host-deny">Denying Hosts in a Reject List</a></h2>
+
+
+
+ <dl>
+ <dt>Description:</dt>
+
+ <dd>
+ <p>We wish to maintain a list of hosts, rather like
+ <code>hosts.deny</code>, and have those hosts blocked from
+ accessing our server.</p>
+ </dd>
+
+ <dt>Solution:</dt>
+
+ <dd>
+<pre class="prettyprint lang-config">RewriteEngine on
+RewriteMap hosts-deny "txt:/path/to/hosts.deny"
+RewriteCond "${hosts-deny:%{REMOTE_ADDR}|NOT-FOUND}" "!=NOT-FOUND" [OR]
+RewriteCond "${hosts-deny:%{REMOTE_HOST}|NOT-FOUND}" "!=NOT-FOUND"
+RewriteRule "^" "-" [F]</pre>
+
+
+<div class="example"><p><code>
+##<br />
+## hosts.deny<br />
+##<br />
+## ATTENTION! This is a map, not a list, even when we treat it as such.<br />
+## mod_rewrite parses it for key/value pairs, so at least a<br />
+## dummy value "-" must be present for each entry.<br />
+##<br />
+<br />
+193.102.180.41 -<br />
+bsdti1.sdm.de -<br />
+192.76.162.40 -<br />
+</code></p></div>
+ </dd>
+
+ <dt>Discussion:</dt>
+ <dd>
+ <p>
+ The second RewriteCond assumes that you have HostNameLookups turned
+ on, so that client IP addresses will be resolved. If that's not the
+ case, you should drop the second RewriteCond, and drop the
+ <code>[OR]</code> flag from the first RewriteCond.
+ </p>
+ </dd>
+ </dl>
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="referer-deflector" id="referer-deflector">Referer-based Deflector</a></h2>
+
+
+
+ <dl>
+ <dt>Description:</dt>
+
+ <dd>
+ <p>Redirect requests based on the Referer from which the request
+ came, with different targets per Referer.</p>
+ </dd>
+
+ <dt>Solution:</dt>
+
+ <dd>
+ <p>The following ruleset uses a map file to associate each Referer
+ with a redirection target.</p>
+
+<pre class="prettyprint lang-config">RewriteMap deflector "txt:/path/to/deflector.map"
+
+RewriteCond "%{HTTP_REFERER}" !=""
+RewriteCond "${deflector:%{HTTP_REFERER}}" "=-"
+RewriteRule "^" "%{HTTP_REFERER}" [R,L]
+
+RewriteCond "%{HTTP_REFERER}" !=""
+RewriteCond "${deflector:%{HTTP_REFERER}|NOT-FOUND}" "!=NOT-FOUND"
+RewriteRule "^" "${deflector:%{HTTP_REFERER}}" [R,L]</pre>
+
+
+ <p>The map file lists redirection targets for each referer, or, if
+ we just wish to redirect back to where they came from, a "-" is
+ placed in the map:</p>
+
+<pre class="prettyprint lang-config">##
+## deflector.map
+##
+
+http://badguys.example.com/bad/index.html -
+http://badguys.example.com/bad/index2.html -
+http://badguys.example.com/bad/index3.html http://somewhere.example.com/</pre>
+
+
+ </dd>
+ </dl>
+
+</div></div>
+<div class="bottomlang">
+<p><span>Available Languages: </span><a href="../en/rewrite/access.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../fr/rewrite/access.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
+</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&amp;A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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