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			496 lines
		
	
	
		
			26 KiB
		
	
	
	
		
			XML
		
	
	
	
	
	
| <?xml version="1.0" encoding="ISO-8859-1"?>
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| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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| <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
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|         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
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|               This file is generated from xml source: DO NOT EDIT
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|         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
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|       -->
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| <title>Security Tips - Apache HTTP Server</title>
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| <link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
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| <link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
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| <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" />
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| <script src="../style/scripts/prettify.js" type="text/javascript">
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| </script>
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| 
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| <link href="../images/favicon.ico" rel="shortcut icon" /></head>
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| <body id="manual-page"><div id="page-header">
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| <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.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 2.5</p>
 | ||
| <img alt="" src="../images/feather.gif" /></div>
 | ||
| <div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
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| <div id="path">
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| <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Miscellaneous Documentation</a></div><div id="page-content"><div id="preamble"><h1>Security Tips</h1>
 | ||
| <div class="toplang">
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| <p><span>Available Languages: </span><a href="../en/misc/security_tips.html" title="English"> en </a> |
 | ||
| <a href="../fr/misc/security_tips.html" hreflang="fr" rel="alternate" title="Fran<61>ais"> fr </a> |
 | ||
| <a href="../ko/misc/security_tips.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
 | ||
| <a href="../tr/misc/security_tips.html" hreflang="tr" rel="alternate" title="T<>rk<72>e"> tr </a></p>
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| </div>
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| 
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|     <p>Some hints and tips on security issues in setting up a web server.
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|     Some of the suggestions will be general, others specific to Apache.</p>
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|   </div>
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| <div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#uptodate">Keep up to Date</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#dos">Denial of Service (DoS) attacks</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#serverroot">Permissions on ServerRoot Directories</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#ssi">Server Side Includes</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#cgi">CGI in General</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#nsaliasedcgi">Non Script Aliased CGI</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#saliasedcgi">Script Aliased CGI</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#dynamic">Other sources of dynamic content</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#dynamicsec">Dynamic content security</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#systemsettings">Protecting System Settings</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#protectserverfiles">Protect Server Files by Default</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#watchyourlogs">Watching Your Logs</a></li>
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| <li><img alt="" src="../images/down.gif" /> <a href="#merging">Merging of configuration sections</a></li>
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| </ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
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| <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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| <div class="section">
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| <h2><a name="uptodate" id="uptodate">Keep up to Date</a></h2>
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| 
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|     <p>The Apache HTTP Server has a good record for security and a
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|     developer community highly concerned about security issues.  But
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|     it is inevitable that some problems -- small or large -- will be
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|     discovered in software after it is released.  For this reason, it
 | ||
|     is crucial to keep aware of updates to the software.  If you have
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|     obtained your version of the HTTP Server directly from Apache, we
 | ||
|     highly recommend you subscribe to the <a href="http://httpd.apache.org/lists.html#http-announce">Apache
 | ||
|     HTTP Server Announcements List</a> where you can keep informed of
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|     new releases and security updates.  Similar services are available
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|     from most third-party distributors of Apache software.</p>
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| 
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|     <p>Of course, most times that a web server is compromised, it is
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|     not because of problems in the HTTP Server code.  Rather, it comes
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|     from problems in add-on code, CGI scripts, or the underlying
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|     Operating System.  You must therefore stay aware of problems and
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|     updates with all the software on your system.</p>
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| 
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|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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| <div class="section">
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| <h2><a name="dos" id="dos">Denial of Service (DoS) attacks</a></h2>
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| 
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|     
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| 
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|     <p>All network servers can be subject to denial of service attacks
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|     that attempt to prevent responses to clients by tying up the
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|     resources of the server.  It is not possible to prevent such
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|     attacks entirely, but you can do certain things to mitigate the
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|     problems that they create.</p>
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| 
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|     <p>Often the most effective anti-DoS tool will be a firewall or
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|     other operating-system configurations.  For example, most
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|     firewalls can be configured to restrict the number of simultaneous
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|     connections from any individual IP address or network, thus
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|     preventing a range of simple attacks.  Of course this is no help
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|     against Distributed Denial of Service attacks (DDoS).</p>
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| 
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|     <p>There are also certain Apache HTTP Server configuration
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|     settings that can help mitigate problems:</p>
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| 
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|     <ul>
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|       <li>The <code class="directive"><a href="../mod/mod_reqtimeout.html#requestreadtimeout">RequestReadTimeout</a></code>
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|       directive allows to limit the time a client may take to send the
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|       request.</li>
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| 
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|       <li>The <code class="directive"><a href="../mod/core.html#timeout">TimeOut</a></code> directive
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|       should be lowered on sites that are subject to DoS attacks.
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|       Setting this to as low as a few seconds may be appropriate.
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|       As <code class="directive"><a href="../mod/core.html#timeout">TimeOut</a></code> is currently
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|       used for several different operations, setting it to a low value
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|       introduces problems with long running CGI scripts.</li>
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| 
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|       <li>The <code class="directive"><a href="../mod/core.html#keepalivetimeout">KeepAliveTimeout</a></code>
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|       directive may be also lowered on sites that are subject to DoS
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|       attacks.  Some sites even turn off the keepalives completely via
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|       <code class="directive"><a href="../mod/core.html#keepalive">KeepAlive</a></code>, which has of course
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|       other drawbacks on performance.</li>
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| 
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|       <li>The values of various timeout-related directives provided by
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|       other modules should be checked.</li>
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| 
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|       <li>The directives
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|       <code class="directive"><a href="../mod/core.html#limitrequestbody">LimitRequestBody</a></code>,
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|       <code class="directive"><a href="../mod/core.html#limitrequestfields">LimitRequestFields</a></code>,
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|       <code class="directive"><a href="../mod/core.html#limitrequestfieldsize">LimitRequestFieldSize</a></code>,
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|       <code class="directive"><a href="../mod/core.html#limitrequestline">LimitRequestLine</a></code>, and
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|       <code class="directive"><a href="../mod/core.html#limitxmlrequestbody">LimitXMLRequestBody</a></code>
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|       should be carefully configured to limit resource consumption
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|       triggered by client input.</li>
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| 
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|       <li>On operating systems that support it, make sure that you use
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|       the <code class="directive"><a href="../mod/core.html#acceptfilter">AcceptFilter</a></code> directive
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|       to offload part of the request processing to the operating
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|       system.  This is active by default in Apache httpd, but may
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|       require reconfiguration of your kernel.</li>
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| 
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|       <li>Tune the <code class="directive"><a href="../mod/mpm_common.html#maxrequestworkers">MaxRequestWorkers</a></code> directive to allow
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|       the server to handle the maximum number of simultaneous
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|       connections without running out of resources.  See also the <a href="perf-tuning.html">performance tuning
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|       documentation</a>.</li>
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| 
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|       <li>The use of a threaded <a href="../mpm.html">mpm</a> may
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|       allow you to handle more simultaneous connections, thereby
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|       mitigating DoS attacks.  Further, the 
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|       <code class="module"><a href="../mod/event.html">event</a></code> mpm
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|       uses asynchronous processing to avoid devoting a thread to each
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|       connection. Due to the nature of the OpenSSL library the
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|       <code class="module"><a href="../mod/event.html">event</a></code> mpm is currently incompatible with
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| 	  <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code> and other input filters. In these
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|       cases it falls back to the behaviour of the
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|       <code class="module"><a href="../mod/worker.html">worker</a></code> mpm.</li>
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| 
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|       <li>There are a number of third-party modules available through
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|       <a href="http://modules.apache.org/">http://modules.apache.org/</a>
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|       that can restrict certain client behaviors and thereby mitigate
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|       DoS problems.</li>
 | ||
| 
 | ||
|     </ul>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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| <div class="section">
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| <h2><a name="serverroot" id="serverroot">Permissions on ServerRoot Directories</a></h2>
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| 
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|     
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| 
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|     <p>In typical operation, Apache is started by the root user, and it
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|     switches to the user defined by the <code class="directive"><a href="../mod/mod_unixd.html#user">User</a></code> directive to serve hits. As is the
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|     case with any command that root executes, you must take care that it is
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|     protected from modification by non-root users. Not only must the files
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|     themselves be writeable only by root, but so must the directories, and
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|     parents of all directories. For example, if you choose to place
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|     ServerRoot in  <code>/usr/local/apache</code> then it is suggested that
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|     you create that directory as root, with commands like these:</p>
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| 
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|     <div class="example"><p><code>
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|       mkdir /usr/local/apache <br />
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|       cd /usr/local/apache <br />
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|       mkdir bin conf logs <br />
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|       chown 0 . bin conf logs <br />
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|       chgrp 0 . bin conf logs <br />
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|       chmod 755 . bin conf logs
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|     </code></p></div>
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| 
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|     <p>It is assumed that <code>/</code>, <code>/usr</code>, and
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|     <code>/usr/local</code> are only modifiable by root. When you install the
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|     <code class="program"><a href="../programs/httpd.html">httpd</a></code> executable, you should ensure that it is
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|     similarly protected:</p>
 | ||
| 
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|     <div class="example"><p><code>
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|       cp httpd /usr/local/apache/bin <br />
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|       chown 0 /usr/local/apache/bin/httpd <br />
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|       chgrp 0 /usr/local/apache/bin/httpd <br />
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|       chmod 511 /usr/local/apache/bin/httpd
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|     </code></p></div>
 | ||
| 
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|     <p>You can create an htdocs subdirectory which is modifiable by other
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|     users -- since root never executes any files out of there, and shouldn't
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|     be creating files in there.</p>
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| 
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|     <p>If you allow non-root users to modify any files that root either
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|     executes or writes on then you open your system to root compromises.
 | ||
|     For example, someone could replace the <code class="program"><a href="../programs/httpd.html">httpd</a></code> binary so
 | ||
|     that the next time you start it, it will execute some arbitrary code. If
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|     the logs directory is writeable (by a non-root user), someone could replace
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|     a log file with a symlink to some other system file, and then root
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|     might overwrite that file with arbitrary data. If the log files
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|     themselves are writeable (by a non-root user), then someone may be
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|     able to overwrite the log itself with bogus data.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="ssi" id="ssi">Server Side Includes</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
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|     <p>Server Side Includes (SSI) present a server administrator with
 | ||
|     several potential security risks.</p>
 | ||
| 
 | ||
|     <p>The first risk is the increased load on the server. All
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|     SSI-enabled files have to be parsed by Apache, whether or not
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|     there are any SSI directives included within the files. While this
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|     load increase is minor, in a shared server environment it can become
 | ||
|     significant.</p>
 | ||
| 
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|     <p>SSI files also pose the same risks that are associated with CGI
 | ||
|     scripts in general. Using the <code>exec cmd</code> element, SSI-enabled
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|     files can execute any CGI script or program under the permissions of the
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|     user and group Apache runs as, as configured in
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|     <code>httpd.conf</code>.</p>
 | ||
| 
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|     <p>There are ways to enhance the security of SSI files while still
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|     taking advantage of the benefits they provide.</p>
 | ||
| 
 | ||
|     <p>To isolate the damage a wayward SSI file can cause, a server
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|     administrator can enable <a href="../suexec.html">suexec</a> as
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|     described in the <a href="#cgi">CGI in General</a> section.</p>
 | ||
| 
 | ||
|     <p>Enabling SSI for files with <code>.html</code> or <code>.htm</code>
 | ||
|     extensions can be dangerous. This is especially true in a shared, or high
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|     traffic, server environment. SSI-enabled files should have a separate
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|     extension, such as the conventional <code>.shtml</code>. This helps keep
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|     server load at a minimum and allows for easier management of risk.</p>
 | ||
| 
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|     <p>Another solution is to disable the ability to run scripts and
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|     programs from SSI pages. To do this replace <code>Includes</code>
 | ||
|     with <code>IncludesNOEXEC</code> in the <code class="directive"><a href="../mod/core.html#options">Options</a></code> directive.  Note that users may
 | ||
|     still use <code><--#include virtual="..." --></code> to execute CGI
 | ||
|     scripts if these scripts are in directories designated by a <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code> directive.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="cgi" id="cgi">CGI in General</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
 | ||
|     <p>First of all, you always have to remember that you must trust the
 | ||
|     writers of the CGI scripts/programs or your ability to spot potential
 | ||
|     security holes in CGI, whether they were deliberate or accidental. CGI
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|     scripts can run essentially arbitrary commands on your system with the
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|     permissions of the web server user and can therefore be extremely
 | ||
|     dangerous if they are not carefully checked.</p>
 | ||
| 
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|     <p>All the CGI scripts will run as the same user, so they have potential
 | ||
|     to conflict (accidentally or deliberately) with other scripts e.g. User
 | ||
|     A hates User B, so he writes a script to trash User B's CGI database. One
 | ||
|     program which can be used to allow scripts to run as different users is
 | ||
|     <a href="../suexec.html">suEXEC</a> which is included with Apache as of
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|     1.2 and is called from special hooks in the Apache server code. Another
 | ||
|     popular way of doing this is with
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|     <a href="http://cgiwrap.sourceforge.net/">CGIWrap</a>.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="nsaliasedcgi" id="nsaliasedcgi">Non Script Aliased CGI</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
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|     <p>Allowing users to execute CGI scripts in any directory should only be
 | ||
|     considered if:</p>
 | ||
| 
 | ||
|     <ul>
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|       <li>You trust your users not to write scripts which will deliberately
 | ||
|           or accidentally expose your system to an attack.</li>
 | ||
|       <li>You consider security at your site to be so feeble in other areas,
 | ||
|           as to make one more potential hole irrelevant.</li>
 | ||
|       <li>You have no users, and nobody ever visits your server.</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="saliasedcgi" id="saliasedcgi">Script Aliased CGI</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
 | ||
|     <p>Limiting CGI to special directories gives the admin control over what
 | ||
|     goes into those directories. This is inevitably more secure than non
 | ||
|     script aliased CGI, but only if users with write access to the
 | ||
|     directories are trusted or the admin is willing to test each
 | ||
|     new CGI script/program for potential security holes.</p>
 | ||
| 
 | ||
|     <p>Most sites choose this option over the non script aliased CGI
 | ||
|     approach.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="dynamic" id="dynamic">Other sources of dynamic content</a></h2>
 | ||
| 
 | ||
|   
 | ||
| 
 | ||
|   <p>Embedded scripting options which run as part of the server itself,
 | ||
|   such as <code>mod_php</code>, <code>mod_perl</code>, <code>mod_tcl</code>,
 | ||
|   and <code>mod_python</code>, run under the identity of the server itself
 | ||
|   (see the <code class="directive"><a href="../mod/mod_unixd.html#user">User</a></code> directive), and
 | ||
|   therefore scripts executed by these engines potentially can access anything
 | ||
|   the server user can. Some scripting engines may provide restrictions, but
 | ||
|   it is better to be safe and assume not.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="dynamicsec" id="dynamicsec">Dynamic content security</a></h2>
 | ||
| 
 | ||
|   
 | ||
| 
 | ||
|   <p>When setting up dynamic content, such as <code>mod_php</code>,
 | ||
|   <code>mod_perl</code> or <code>mod_python</code>, many security considerations
 | ||
|   get out of the scope of <code>httpd</code> itself, and you need to consult
 | ||
|   documentation from those modules. For example, PHP lets you setup <a href="http://www.php.net/manual/en/ini.sect.safe-mode.php">Safe Mode</a>,
 | ||
|   which is most usually disabled by default. Another example is <a href="http://www.hardened-php.net/suhosin/">Suhosin</a>, a PHP addon for more
 | ||
|   security. For more information about those, consult each project
 | ||
|   documentation.</p>
 | ||
| 
 | ||
|   <p>At the Apache level, a module named <a href="http://modsecurity.org/">mod_security</a>
 | ||
|   can be seen as a HTTP firewall and, provided you configure it finely enough,
 | ||
|   can help you enhance your dynamic content security.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="systemsettings" id="systemsettings">Protecting System Settings</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
 | ||
|     <p>To run a really tight ship, you'll want to stop users from setting
 | ||
|     up <code>.htaccess</code> files which can override security features
 | ||
|     you've configured. Here's one way to do it.</p>
 | ||
| 
 | ||
|     <p>In the server configuration file, put</p>
 | ||
| 
 | ||
|     <pre class="prettyprint lang-config">
 | ||
| <Directory />
 | ||
|     AllowOverride None
 | ||
| </Directory>
 | ||
|     </pre>
 | ||
| 
 | ||
| 
 | ||
|     <p>This prevents the use of <code>.htaccess</code> files in all
 | ||
|     directories apart from those specifically enabled.</p>
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="protectserverfiles" id="protectserverfiles">Protect Server Files by Default</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
 | ||
|     <p>One aspect of Apache which is occasionally misunderstood is the
 | ||
|     feature of default access. That is, unless you take steps to change it,
 | ||
|     if the server can find its way to a file through normal URL mapping
 | ||
|     rules, it can serve it to clients.</p>
 | ||
| 
 | ||
|     <p>For instance, consider the following example:</p>
 | ||
| 
 | ||
|     <div class="example"><p><code>
 | ||
|       # cd /; ln -s / public_html <br />
 | ||
|       Accessing <code>http://localhost/~root/</code>
 | ||
|     </code></p></div>
 | ||
| 
 | ||
|     <p>This would allow clients to walk through the entire filesystem. To
 | ||
|     work around this, add the following block to your server's
 | ||
|     configuration:</p>
 | ||
| 
 | ||
|     <pre class="prettyprint lang-config">
 | ||
| <Directory />
 | ||
|     Require all denied
 | ||
| </Directory>
 | ||
|     </pre>
 | ||
| 
 | ||
| 
 | ||
|     <p>This will forbid default access to filesystem locations. Add
 | ||
|     appropriate <code class="directive"><a href="../mod/core.html#directory">Directory</a></code> blocks to
 | ||
|     allow access only in those areas you wish. For example,</p>
 | ||
| 
 | ||
|     <pre class="prettyprint lang-config">
 | ||
| <Directory /usr/users/*/public_html>
 | ||
|     Require all granted
 | ||
| </Directory>
 | ||
| <Directory /usr/local/httpd>
 | ||
|     Require all granted
 | ||
| </Directory>
 | ||
|     </pre>
 | ||
| 
 | ||
| 
 | ||
|     <p>Pay particular attention to the interactions of <code class="directive"><a href="../mod/core.html#location">Location</a></code> and <code class="directive"><a href="../mod/core.html#directory">Directory</a></code> directives; for instance, even
 | ||
|     if <code><Directory /></code> denies access, a <code>
 | ||
|     <Location /></code> directive might overturn it.</p>
 | ||
| 
 | ||
|     <p>Also be wary of playing games with the <code class="directive"><a href="../mod/mod_userdir.html#userdir">UserDir</a></code> directive; setting it to
 | ||
|     something like <code>./</code> would have the same effect, for root, as
 | ||
|     the first example above. We strongly
 | ||
|     recommend that you include the following line in your server
 | ||
|     configuration files:</p>
 | ||
| 
 | ||
|     <pre class="prettyprint lang-config">UserDir disabled root</pre>
 | ||
| 
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="watchyourlogs" id="watchyourlogs">Watching Your Logs</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
 | ||
|     <p>To keep up-to-date with what is actually going on against your server
 | ||
|     you have to check the <a href="../logs.html">Log Files</a>.  Even though
 | ||
|     the log files only reports what has already happened, they will give you
 | ||
|     some understanding of what attacks is thrown against the server and
 | ||
|     allow you to check if the necessary level of security is present.</p>
 | ||
| 
 | ||
|     <p>A couple of examples:</p>
 | ||
| 
 | ||
|     <div class="example"><p><code>
 | ||
|       grep -c "/jsp/source.jsp?/jsp/ /jsp/source.jsp??" access_log <br />
 | ||
|       grep "client denied" error_log | tail -n 10
 | ||
|     </code></p></div>
 | ||
| 
 | ||
|     <p>The first example will list the number of attacks trying to exploit the
 | ||
|     <a href="http://online.securityfocus.com/bid/4876/info/">Apache Tomcat
 | ||
|     Source.JSP Malformed Request Information Disclosure Vulnerability</a>,
 | ||
|     the second example will list the ten last denied clients, for example:</p>
 | ||
| 
 | ||
|     <div class="example"><p><code>
 | ||
|       [Thu Jul 11 17:18:39 2002] [error] [client foo.example.com] client denied
 | ||
|       by server configuration: /usr/local/apache/htdocs/.htpasswd
 | ||
|     </code></p></div>
 | ||
| 
 | ||
|     <p>As you can see, the log files only report what already has happened, so
 | ||
|     if the client had been able to access the <code>.htpasswd</code> file you
 | ||
|     would have seen something similar to:</p>
 | ||
| 
 | ||
|     <div class="example"><p><code>
 | ||
|       foo.example.com - - [12/Jul/2002:01:59:13 +0200] "GET /.htpasswd HTTP/1.1"
 | ||
|     </code></p></div>
 | ||
| 
 | ||
|     <p>in your <a href="../logs.html#accesslog">Access Log</a>. This means
 | ||
|     you probably commented out the following in your server configuration
 | ||
|     file:</p>
 | ||
| 
 | ||
|     <pre class="prettyprint lang-config">
 | ||
| <Files ".ht*">
 | ||
|     Require all denied
 | ||
| </Files>
 | ||
|     </pre>
 | ||
| 
 | ||
| 
 | ||
|   </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | ||
| <div class="section">
 | ||
| <h2><a name="merging" id="merging">Merging of configuration sections</a></h2>
 | ||
| 
 | ||
|     
 | ||
| 
 | ||
|     <p> The merging of configuration sections is complicated and sometimes
 | ||
|     directive specific.  Always test your changes when creating dependencies
 | ||
|     on how directives are merged.</p>
 | ||
| 
 | ||
|     <p> For modules that don't implement any merging logic, such as 
 | ||
|     <code class="directive">mod_access_compat</code>, the behavior in later sections
 | ||
|     depends on whether the later section has any directives
 | ||
|     from the module.  The configuration is inherited until a change is made, 
 | ||
|     at which point the configuration is <em>replaced</em> and not merged.</p>
 | ||
|   </div></div>
 | ||
| <div class="bottomlang">
 | ||
| <p><span>Available Languages: </span><a href="../en/misc/security_tips.html" title="English"> en </a> |
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| <a href="../fr/misc/security_tips.html" hreflang="fr" rel="alternate" title="Fran<61>ais"> fr </a> |
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| </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&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again 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 Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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