htdocs/manual/server-wide.html.en - httpd - Git at Google

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     <h1 align="center">Server-Wide Configuration</h1>

     <p>This document explains some of the directives provided by
     the <a href="mod/core.html">core</a> server which are used to
     configure the basic operations of the server.</p>

     <ul>
       <li><a href="#identification">Server Identification</a></li>

       <li><a href="#locations">File Locations</a></li>

       <li><a href="#process">Process Creation</a></li>

       <li><a href="#network">Network Configuration</a></li>

       <li><a href="#resource">Limiting Resource Usage</a></li>
     </ul>
     <hr />

     <h2><a id="identification" name="identification">Server
     Identification</a></h2>

     <table border="1">
       <tr>
         <td valign="top"><strong>Related Directives</strong><br />
          <br />
          <a href="mod/core.html#servername">ServerName</a><br />
          <a href="mod/core.html#serveradmin">ServerAdmin</a><br />
          <a
         href="mod/core.html#serversignature">ServerSignature</a><br />
          <a
         href="mod/core.html#servertokens">ServerTokens</a><br />
          <a
         href="mod/core.html#usecanonicalname">UseCanonicalName</a><br />
          </td>
       </tr>
     </table>

     <p>The <code>ServerAdmin</code> and <code>ServerTokens</code>
     directives control what information about the server will be
     presented in server-generated documents such as error messages.
     The <code>ServerTokens</code> directive sets the value of the
     Server HTTP response header field.</p>

     <p>The <code>ServerName</code> and
     <code>UseCanonicalName</code> directives are used by the server
     to determine how to construct self-referential URLs. For
     example, when a client requests a directory, but does not
     include the trailing slash in the directory name, Apache must
     redirect the client to the full name including the trailing
     slash so that the client will correctly resolve relative
     references in the document.</p>
     <hr />

     <h2><a id="locations" name="locations">File Locations</a></h2>

     <table border="1">
       <tr>
         <td valign="top"><strong>Related Directives</strong><br />
          <br />
          <a
         href="mod/core.html#coredumpdirectory">CoreDumpDirectory</a><br />
          <a
         href="mod/core.html#documentroot">DocumentRoot</a><br />
          <a href="mod/core.html#errorlog">ErrorLog</a><br />
          <a href="mod/core.html#lockfile">Lockfile</a><br />
          <a href="mod/core.html#pidfile">PidFile</a><br />
          <a
         href="mod/core.html#scoreboardfile">ScoreBoardFile</a><br />
          <a href="mod/core.html#serverroot">ServerRoot</a><br />
          </td>
       </tr>
     </table>

     <p>These directives control the locations of the various files
     that Apache needs for proper operation. When the pathname used
     does not begin with a slash "/", the files are located relative
     to the <code>ServerRoot</code>. Be careful about locating files
     in paths which are writable by non-root users. See the <a
     href="misc/security_tips.html">security tips</a> documentation
     for more details.</p>
     <hr />

     <h2><a id="process" name="process">Process Creation</a></h2>

     <table border="1">
       <tr>
         <td valign="top"><strong>Related Directives</strong><br />
          <br />
          <a
         href="mod/core.html#bs2000account">BS2000Account</a><br />
          <a href="mod/core.html#group">Group</a><br />
          <a href="mod/core.html#maxclients">MaxClients</a><br />
          <a
         href="mod/core.html#maxrequestsperchild">MaxRequestsPerChild</a><br />
          <a
         href="mod/core.html#maxspareservers">MaxSpareServers</a><br />
          <a
         href="mod/core.html#minspareservers">MinSpareServers</a><br />
          <a href="mod/core.html#servertype">ServerType</a><br />
          <a
         href="mod/core.html#startservers">StartServers</a><br />
          <a
         href="mod/core.html#threadsperchild">ThreadsPerChild</a><br />
          <a href="mod/core.html#user">User</a><br />
          </td>
       </tr>
     </table>

     <p>When <code>ServerType</code> is set to its recommended value
     of <code>Standalone</code>, Apache 1.3 for Unix is a
     pre-forking web server. A single control process is responsible
     for launching child processes which listen for connections and
     serve them when they arrive. Apache always tries to maintain
     several <em>spare</em> or idle server processes, which stand
     ready to serve incoming requests. In this way, clients do not
     need to wait for a new child processes to be forked before
     their requests can be served.</p>

     <p>The <code>StartServers</code>, <code>MinSpareServers</code>,
     <code>MaxSpareServers</code>, and <code>MaxServers</code>
     regulate how the parent process creates children to serve
     requests. In general, Apache is very self-regulating, so most
     sites do not need to adjust these directives from their default
     values. Sites which need to serve more than 256 simultaneous
     requests may need to increase <code>MaxClients</code>, while
     sites with limited memory may need to decrease
     <code>MaxClients</code> to keep the server from thrashing
     (swapping memory to disk and back). More information about
     tuning process creation is provided in the <a
     href="misc/perf-tuning.html">performance hints</a>
     documentation.</p>

     <p>While the parent process is usually started as root under
     Unix in order to bind to port 80, the child processes are
     launched by Apache as a less-privileged user. The
     <code>User</code> and <code>Group</code> directives are used to
     set the privileges of the Apache child processes. The child
     processes must be able to read all the content that will be
     served, but should have as few privileges beyond that as
     possible. In addition, unless <a href="suexec.html">suexec</a>
     is used, these directives also set the privileges which will be
     inherited by CGI scripts.</p>

     <p><code>MaxRequestsPerChild</code> controls how frequently the
     server recycles processes by killing old ones and launching new
     ones.</p>

     <p>Under Windows, Apache launches one control process and one
     child process. The child process creates multiple threads to
     serve requests. The number of threads is controlled by the
     <code>ThreadsPerChild</code> directive.</p>
     <hr />

     <h2><a id="network" name="network">Network
     Configuration</a></h2>

     <table border="1">
       <tr>
         <td valign="top"><strong>Related Directives</strong><br />
          <br />
          <a href="mod/core.html#bindaddress">BindAddress</a><br />
          <a href="mod/core.html#keepalive">KeepAlive</a><br />
          <a
         href="mod/core.html#keepalivetimeout">KeepAliveTimeout</a><br />
          <a href="mod/core.html#listen">Listen</a><br />
          <a
         href="mod/core.html#listenbacklog">ListenBackLog</a><br />
          <a
         href="mod/core.html#acceptfilter">AcceptFilter</a><br />
          <a href="mod/core.html#acceptmutex">AcceptMutex</a><br />
          <a
         href="mod/core.html#maxkeepaliverequests">MaxKeepAliveRequests</a><br />
          <a href="mod/core.html#port">Port</a><br />
          <a
         href="mod/core.html#sendbuffersize">SendBufferSize</a><br />
          <a href="mod/core.html#timeout">TimeOut</a><br />
          </td>
       </tr>
     </table>

     <p>When Apache starts, it connects to some port and address on
     the local machine and waits for incoming requests. By default,
     it listens to all addresses on the machine, and to the port as
     specified by the <code>Port</code> directive in the server
     configuration. However, it can be told to listen to more than
     one port, to listen to only selected addresses, or a
     combination. This is often combined with the <a
     href="vhosts/">Virtual Host</a> feature which determines how
     Apache responds to different IP addresses, hostnames and
     ports.</p>

     <p>There are two directives used to restrict or specify which
     addresses and ports Apache listens to. The
     <code>BindAddress</code> directive is used to restrict the
     server to listening to a single IP address. The
     <code>Listen</code> directive can be used to specify multiple
     IP addresses and/or Ports to which Apache will listen.</p>

     <p>The <code>ListenBackLog</code>, <code>SendBufferSize</code>,
     and <code>TimeOut</code> directives are used to adjust how
     Apache interacts with the network.<code>AcceptFilter</code>
     controls a BSD specific filter optimization. See the BSD
     section on <a href="misc/perf-bsd44.html">performance hints</a>
     documentation. <code>AcceptMutex</code> controls which accept
     mutex method will be used. For an explanation of what this is
     and why it's needed, see the <a
     href="misc/perf-tuning.html">performance tuning guide</a></p>

     <p>The <code>KeepAlive</code>, <code>KeepAliveTimeout</code>,
     and <code>MaxKeepAliveRequests</code> directives are used to
     configure how Apache handles persistent connections.</p>
     <hr />

     <h2><a id="resource" name="resource">Limiting Resource
     Usage</a></h2>

     <table border="1">
       <tr>
         <td valign="top"><strong>Related Directives</strong><br />
          <br />
          <a
         href="mod/core.html#limitrequestbody">LimitRequestBody</a><br />
          <a
         href="mod/core.html#limitrequestfields">LimitRequestFields</a><br />
          <a
         href="mod/core.html#limitrequestfieldsize">LimitRequestFieldsize</a><br />
          <a
         href="mod/core.html#limitrequestline">LimitRequestLine</a><br />
          <a href="mod/core.html#rlimitcpu">RLimitCPU</a><br />
          <a href="mod/core.html#rlimitmem">RLimitMEM</a><br />
          <a href="mod/core.html#rlimitnproc">RLimitNPROC</a><br />
          <a
         href="mod/core.html#threadstacksize">ThreadStackSize</a><br />
          </td>
       </tr>
     </table>

     <p>The <code>LimitRequest</code>* directives are used to place
     limits on the amount of resources Apache will use in reading
     requests from clients. By limiting these values, some kinds of
     denial of service attacks can be mitigated.</p>

     <p>The <code>RLimit</code>* directives are used to limit the
     amount of resources which can be used by processes forked off
     from the Apache children. In particular, this will control
     resources used by CGI scripts and SSI exec commands.</p>

     <p>The <code>ThreadStackSize</code> directive is used only on
     Netware to control the stack size.</p>
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	<head>
	<META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW">
	<meta name="generator" content="HTML Tidy, see www.w3.org" />

	<title>Server-Wide Configuration</title>
	</head>
	<!-- Background white, links blue (unvisited), navy (visited), red (active) -->

	<body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
	vlink="#000080" alink="#FF0000">
	<!--#include virtual="header.html" -->

	<h1 align="center">Server-Wide Configuration</h1>

	<p>This document explains some of the directives provided by
	the <a href="mod/core.html">core</a> server which are used to
	configure the basic operations of the server.</p>

	<ul>
	<li><a href="#identification">Server Identification</a></li>

	<li><a href="#locations">File Locations</a></li>

	<li><a href="#process">Process Creation</a></li>

	<li><a href="#network">Network Configuration</a></li>

	<li><a href="#resource">Limiting Resource Usage</a></li>
	</ul>
	<hr />

	<h2><a id="identification" name="identification">Server
	Identification</a></h2>

	<table border="1">
	<tr>
	<td valign="top"><strong>Related Directives</strong><br />
	<br />
	<a href="mod/core.html#servername">ServerName</a><br />
	<a href="mod/core.html#serveradmin">ServerAdmin</a><br />
	<a
	href="mod/core.html#serversignature">ServerSignature</a><br />
	<a
	href="mod/core.html#servertokens">ServerTokens</a><br />
	<a
	href="mod/core.html#usecanonicalname">UseCanonicalName</a><br />
	</td>
	</tr>
	</table>

	<p>The <code>ServerAdmin</code> and <code>ServerTokens</code>
	directives control what information about the server will be
	presented in server-generated documents such as error messages.
	The <code>ServerTokens</code> directive sets the value of the
	Server HTTP response header field.</p>

	<p>The <code>ServerName</code> and
	<code>UseCanonicalName</code> directives are used by the server
	to determine how to construct self-referential URLs. For
	example, when a client requests a directory, but does not
	include the trailing slash in the directory name, Apache must
	redirect the client to the full name including the trailing
	slash so that the client will correctly resolve relative
	references in the document.</p>
	<hr />

	<h2><a id="locations" name="locations">File Locations</a></h2>

	<table border="1">
	<tr>
	<td valign="top"><strong>Related Directives</strong><br />
	<br />
	<a
	href="mod/core.html#coredumpdirectory">CoreDumpDirectory</a><br />
	<a
	href="mod/core.html#documentroot">DocumentRoot</a><br />
	<a href="mod/core.html#errorlog">ErrorLog</a><br />
	<a href="mod/core.html#lockfile">Lockfile</a><br />
	<a href="mod/core.html#pidfile">PidFile</a><br />
	<a
	href="mod/core.html#scoreboardfile">ScoreBoardFile</a><br />
	<a href="mod/core.html#serverroot">ServerRoot</a><br />
	</td>
	</tr>
	</table>

	<p>These directives control the locations of the various files
	that Apache needs for proper operation. When the pathname used
	does not begin with a slash "/", the files are located relative
	to the <code>ServerRoot</code>. Be careful about locating files
	in paths which are writable by non-root users. See the <a
	href="misc/security_tips.html">security tips</a> documentation
	for more details.</p>
	<hr />

	<h2><a id="process" name="process">Process Creation</a></h2>

	<table border="1">
	<tr>
	<td valign="top"><strong>Related Directives</strong><br />
	<br />
	<a
	href="mod/core.html#bs2000account">BS2000Account</a><br />
	<a href="mod/core.html#group">Group</a><br />
	<a href="mod/core.html#maxclients">MaxClients</a><br />
	<a
	href="mod/core.html#maxrequestsperchild">MaxRequestsPerChild</a><br />
	<a
	href="mod/core.html#maxspareservers">MaxSpareServers</a><br />
	<a
	href="mod/core.html#minspareservers">MinSpareServers</a><br />
	<a href="mod/core.html#servertype">ServerType</a><br />
	<a
	href="mod/core.html#startservers">StartServers</a><br />
	<a
	href="mod/core.html#threadsperchild">ThreadsPerChild</a><br />
	<a href="mod/core.html#user">User</a><br />
	</td>
	</tr>
	</table>

	<p>When <code>ServerType</code> is set to its recommended value
	of <code>Standalone</code>, Apache 1.3 for Unix is a
	pre-forking web server. A single control process is responsible
	for launching child processes which listen for connections and
	serve them when they arrive. Apache always tries to maintain
	several <em>spare</em> or idle server processes, which stand
	ready to serve incoming requests. In this way, clients do not
	need to wait for a new child processes to be forked before
	their requests can be served.</p>

	<p>The <code>StartServers</code>, <code>MinSpareServers</code>,
	<code>MaxSpareServers</code>, and <code>MaxServers</code>
	regulate how the parent process creates children to serve
	requests. In general, Apache is very self-regulating, so most
	sites do not need to adjust these directives from their default
	values. Sites which need to serve more than 256 simultaneous
	requests may need to increase <code>MaxClients</code>, while
	sites with limited memory may need to decrease
	<code>MaxClients</code> to keep the server from thrashing
	(swapping memory to disk and back). More information about
	tuning process creation is provided in the <a
	href="misc/perf-tuning.html">performance hints</a>
	documentation.</p>

	<p>While the parent process is usually started as root under
	Unix in order to bind to port 80, the child processes are
	launched by Apache as a less-privileged user. The
	<code>User</code> and <code>Group</code> directives are used to
	set the privileges of the Apache child processes. The child
	processes must be able to read all the content that will be
	served, but should have as few privileges beyond that as
	possible. In addition, unless <a href="suexec.html">suexec</a>
	is used, these directives also set the privileges which will be
	inherited by CGI scripts.</p>

	<p><code>MaxRequestsPerChild</code> controls how frequently the
	server recycles processes by killing old ones and launching new
	ones.</p>

	<p>Under Windows, Apache launches one control process and one
	child process. The child process creates multiple threads to
	serve requests. The number of threads is controlled by the
	<code>ThreadsPerChild</code> directive.</p>
	<hr />

	<h2><a id="network" name="network">Network
	Configuration</a></h2>

	<table border="1">
	<tr>
	<td valign="top"><strong>Related Directives</strong><br />
	<br />
	<a href="mod/core.html#bindaddress">BindAddress</a><br />
	<a href="mod/core.html#keepalive">KeepAlive</a><br />
	<a
	href="mod/core.html#keepalivetimeout">KeepAliveTimeout</a><br />
	<a href="mod/core.html#listen">Listen</a><br />
	<a
	href="mod/core.html#listenbacklog">ListenBackLog</a><br />
	<a
	href="mod/core.html#acceptfilter">AcceptFilter</a><br />
	<a href="mod/core.html#acceptmutex">AcceptMutex</a><br />
	<a
	href="mod/core.html#maxkeepaliverequests">MaxKeepAliveRequests</a><br />
	<a href="mod/core.html#port">Port</a><br />
	<a
	href="mod/core.html#sendbuffersize">SendBufferSize</a><br />
	<a href="mod/core.html#timeout">TimeOut</a><br />
	</td>
	</tr>
	</table>

	<p>When Apache starts, it connects to some port and address on
	the local machine and waits for incoming requests. By default,
	it listens to all addresses on the machine, and to the port as
	specified by the <code>Port</code> directive in the server
	configuration. However, it can be told to listen to more than
	one port, to listen to only selected addresses, or a
	combination. This is often combined with the <a
	href="vhosts/">Virtual Host</a> feature which determines how
	Apache responds to different IP addresses, hostnames and
	ports.</p>

	<p>There are two directives used to restrict or specify which
	addresses and ports Apache listens to. The
	<code>BindAddress</code> directive is used to restrict the
	server to listening to a single IP address. The
	<code>Listen</code> directive can be used to specify multiple
	IP addresses and/or Ports to which Apache will listen.</p>

	<p>The <code>ListenBackLog</code>, <code>SendBufferSize</code>,
	and <code>TimeOut</code> directives are used to adjust how
	Apache interacts with the network.<code>AcceptFilter</code>
	controls a BSD specific filter optimization. See the BSD
	section on <a href="misc/perf-bsd44.html">performance hints</a>
	documentation. <code>AcceptMutex</code> controls which accept
	mutex method will be used. For an explanation of what this is
	and why it's needed, see the <a
	href="misc/perf-tuning.html">performance tuning guide</a></p>

	<p>The <code>KeepAlive</code>, <code>KeepAliveTimeout</code>,
	and <code>MaxKeepAliveRequests</code> directives are used to
	configure how Apache handles persistent connections.</p>
	<hr />

	<h2><a id="resource" name="resource">Limiting Resource
	Usage</a></h2>

	<table border="1">
	<tr>
	<td valign="top"><strong>Related Directives</strong><br />
	<br />
	<a
	href="mod/core.html#limitrequestbody">LimitRequestBody</a><br />
	<a
	href="mod/core.html#limitrequestfields">LimitRequestFields</a><br />
	<a
	href="mod/core.html#limitrequestfieldsize">LimitRequestFieldsize</a><br />
	<a
	href="mod/core.html#limitrequestline">LimitRequestLine</a><br />
	<a href="mod/core.html#rlimitcpu">RLimitCPU</a><br />
	<a href="mod/core.html#rlimitmem">RLimitMEM</a><br />
	<a href="mod/core.html#rlimitnproc">RLimitNPROC</a><br />
	<a
	href="mod/core.html#threadstacksize">ThreadStackSize</a><br />
	</td>
	</tr>
	</table>

	<p>The <code>LimitRequest</code>* directives are used to place
	limits on the amount of resources Apache will use in reading
	requests from clients. By limiting these values, some kinds of
	denial of service attacks can be mitigated.</p>

	<p>The <code>RLimit</code>* directives are used to limit the
	amount of resources which can be used by processes forked off
	from the Apache children. In particular, this will control
	resources used by CGI scripts and SSI exec commands.</p>

	<p>The <code>ThreadStackSize</code> directive is used only on
	Netware to control the stack size.</p>
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	</body>
	</html>