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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<TITLE>Server-Wide Configuration</TITLE>
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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 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 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 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 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#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.</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 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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