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<title>Apache Core Features</title>
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<h1 align="center">Apache Core Features</h1>
<p>These configuration parameters control the core Apache
features, and are always available.</p>
<h2>Directives</h2>
<ul>
<li><a href="#acceptfilter">AcceptFilter</a></li>
<li><a href="#acceptmutex">AcceptMutex</a></li>
<li><a href="#accessconfig">AccessConfig</a></li>
<li><a href="#accessfilename">AccessFileName</a></li>
<li><a href="#adddefaultcharset">AddDefaultCharset</a></li>
<li><a href="#addmodule">AddModule</a></li>
<li><a href="#allowoverride">AllowOverride</a></li>
<li><a href="#authname">AuthName</a></li>
<li><a href="#AuthDigestRealmSeed">AuthDigestRealmSeed</a></li>
<li><a href="#authtype">AuthType</a></li>
<li><a href="#bindaddress">BindAddress</a></li>
<li><a href="#bs2000account">BS2000Account</a></li>
<li><a href="#cgicommandargs">CGICommandArgs</a></li>
<li><a href="#clearmodulelist">ClearModuleList</a></li>
<li><a href="#contentdigest">ContentDigest</a></li>
<li><a href="#coredumpdirectory">CoreDumpDirectory</a></li>
<li><a href="#defaulttype">DefaultType</a></li>
<li><a href="#directory">&lt;Directory&gt;</a></li>
<li><a href="#directorymatch">&lt;DirectoryMatch&gt;</a></li>
<li><a href="#documentroot">DocumentRoot</a></li>
<li><a href="#ebcdicconvert">EBCDICConvert</a></li>
<li><a
href="#ebcdicconvertbytype">EBCDICConvertByType</a></li>
<li><a href="#ebcdickludge">EBCDICKludge</a></li>
<li><a href="#enableexceptionhook">EnableExceptionHook</a></li>
<li><a href="#errordocument">ErrorDocument</a></li>
<li><a href="#errorlog">ErrorLog</a></li>
<li><a href="#fileetag">FileETag</a></li>
<li><a href="#files">&lt;Files&gt;</a></li>
<li><a href="#filesmatch">&lt;FilesMatch&gt;</a></li>
<li><a href="#group">Group</a></li>
<li><a href="#hostnamelookups">HostnameLookups</a></li>
<li><a href="#identitycheck">IdentityCheck</a></li>
<li><a href="#ifdefine">&lt;IfDefine&gt;</a></li>
<li><a href="#ifmodule">&lt;IfModule&gt;</a></li>
<li><a href="#include">Include</a></li>
<li><a href="#keepalive">KeepAlive</a></li>
<li><a href="#keepalivetimeout">KeepAliveTimeout</a></li>
<li><a href="#limit">&lt;Limit&gt;</a></li>
<li><a href="#limitexcept">&lt;LimitExcept&gt;</a></li>
<li><a href="#limitinternalrecursion">LimitInternalRecursion</a></li>
<li><a href="#limitrequestbody">LimitRequestBody</a></li>
<li><a href="#limitrequestfields">LimitRequestFields</a></li>
<li><a
href="#limitrequestfieldsize">LimitRequestFieldsize</a></li>
<li><a href="#limitrequestline">LimitRequestLine</a></li>
<li><a href="#listen">Listen</a></li>
<li><a href="#listenbacklog">ListenBacklog</a></li>
<li><a href="#location">&lt;Location&gt;</a></li>
<li><a href="#locationmatch">&lt;LocationMatch&gt;</a></li>
<li><a href="#lockfile">LockFile</a></li>
<li><a href="#loglevel">LogLevel</a></li>
<li><a href="#maxclients">MaxClients</a></li>
<li><a
href="#maxkeepaliverequests">MaxKeepAliveRequests</a></li>
<li><a
href="#maxrequestsperchild">MaxRequestsPerChild</a></li>
<li><a href="#maxspareservers">MaxSpareServers</a></li>
<li><a href="#minspareservers">MinSpareServers</a></li>
<li><a href="#namevirtualhost">NameVirtualHost</a></li>
<li><a href="#options">Options</a></li>
<li><a href="#pidfile">PidFile</a></li>
<li><a href="#port">Port</a></li>
<li><a href="#protocolreqcheck">ProtocolReqCheck</a></li>
<li><a href="#require">Require</a></li>
<li><a href="#resourceconfig">ResourceConfig</a></li>
<li><a href="#rlimitcpu">RLimitCPU</a></li>
<li><a href="#rlimitmem">RLimitMEM</a></li>
<li><a href="#rlimitnproc">RLimitNPROC</a></li>
<li><a href="#satisfy">Satisfy</a></li>
<li><a href="#scoreboardfile">ScoreBoardFile</a></li>
<li><a
href="#scriptinterpretersource">ScriptInterpreterSource</a></li>
<li><a href="#sendbuffersize">SendBufferSize</a></li>
<li><a href="#serveradmin">ServerAdmin</a></li>
<li><a href="#serveralias">ServerAlias</a></li>
<li><a href="#servername">ServerName</a></li>
<li><a href="#serverpath">ServerPath</a></li>
<li><a href="#serverroot">ServerRoot</a></li>
<li><a href="#serversignature">ServerSignature</a></li>
<li><a href="#servertokens">ServerTokens</a></li>
<li><a href="#servertype">ServerType</a></li>
<li><a href="#shmemuidisuser">ShmemUIDisUser</a></li>
<li><a href="#startservers">StartServers</a></li>
<li><a href="#threadsperchild">ThreadsPerChild</a></li>
<li><a href="#threadstacksize">ThreadStackSize</a></li>
<li><a href="#timeout">TimeOut</a></li>
<li><a href="#traceenable">TraceEnable</a></li>
<li><a href="#usecanonicalname">UseCanonicalName</a></li>
<li><a href="#user">User</a></li>
<li><a href="#virtualhost">&lt;VirtualHost&gt;</a></li>
</ul>
<hr />
<h2><a id="acceptfilter" name="acceptfilter">AcceptFilter
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AcceptFilter
on|off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>AcceptFilter
on</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> AcceptFilter is
available in Apache 1.3.22 and later
<p><code>AcceptFilter</code> controls a BSD specific filter
optimization. It is compiled in by default - and switched on by
default if your system supports it (setsocketopt() option
SO_ACCEPTFILTER). Currently only FreeBSD supports this.</p>
<p>See the filter section on <a
href="../misc/perf-bsd44.html">performance hints</a> for more
information.</p>
<p>The compile time flag <code>AP_ACCEPTFILTER_OFF</code> can
be used to change the default to 'off'. <code>httpd -V</code>
and <code>httpd -L</code> will show compile time defaults and
whether or not SO_ACCEPTFILTER was defined during the
compile.</p>
<hr />
<h2><a id="acceptmutex" name="acceptmutex">AcceptMutex
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AcceptMutex
uslock|pthread|sysvsem|fcntl|flock|os2sem|tpfcore|none|default<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>AcceptMutex
default</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core <br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> AcceptMutex is
available in Apache 1.3.21 and later.
<p><code>AcceptMutex</code> controls which accept() mutex
method Apache will use. Not all methods are available on all
platforms, since the suite of methods is determined at
compile-time. For a list of which methods are available for
your particular build, the <code>httpd -V</code> command line
option will list them out.</p>
<p>The compile time flags <code>-D
HAVE_METHOD_SERIALIZED_ACCEPT</code> can be used to add
different methods to your build, or one can edit the
<code>include/ap_config.h</code> file for your particular
platform.</p>
<p>This directive has no effect on Microsoft Windows.</p>
<p>See the <a href="../misc/perf-tuning.html">performance tuning
guide</a> for more information.</p>
<hr />
<h2><a id="accessconfig" name="accessconfig">AccessConfig
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AccessConfig
<em>file-path</em>|<em>directory-path</em>|<em>wildcard-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>AccessConfig
conf/access.conf</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core <br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> The ability to
specify a directory, rather than a file name, is only available in
Apache 1.3.13 and later. This directive will be eliminated in version
2.0.
<p>The server will read this file for more directives after
reading the <a href="#resourceconfig">ResourceConfig</a> file.
<em>File-path</em> is relative to the <a
href="#serverroot">ServerRoot</a>. This feature can be disabled
using:</p>
<blockquote>
<code>AccessConfig /dev/null</code>
</blockquote>
Or, on Win32 servers,
<blockquote>
<code>AccessConfig nul</code>
</blockquote>
Historically, this file only contained <a
href="#directory">&lt;Directory&gt;</a> sections; in fact it
can now contain any server directive allowed in the <em>server
config</em> context. However, since Apache version 1.3.4,
the default <code>access.conf</code> file which ships with
Apache contains only comments, and all directives are placed
in the main server configuration file, <code>httpd.conf</code>.
<p>If <code>AccessConfig</code> points to a directory, rather than a
file, Apache will read all files in that directory, and any
subdirectory, and parse those as configuration files.
</p>
<p>Alternatively you can use a wildcard to limit the scope; i.e
to only *.conf files.
</p>
<p>Note that by default <em>any</em> file in the specified
directory will be loaded as a configuration file.
</p>
<p>
So make sure that you don't have stray files in
this directory by mistake, such as temporary files created by your
editor, for example.</p>
<p><strong>See also:</strong> <a href="#include">Include</a> and <a
href="#resourceconfig">ResourceConfig</a>.</p>
<hr />
<h2><a id="accessfilename" name="accessfilename">AccessFileName
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AccessFileName
<em>filename</em> [<em>filename</em>] ...<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>AccessFileName
.htaccess</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> AccessFileName
can accept more than one filename only in Apache 1.3 and later
<p>When returning a document to the client the server looks for
the first existing access control file from this list of names
in every directory of the path to the document, if access
control files are enabled for that directory. For example:</p>
<blockquote>
<code>AccessFileName .acl</code>
</blockquote>
before returning the document /usr/local/web/index.html, the
server will read /.acl, /usr/.acl, /usr/local/.acl and
/usr/local/web/.acl for directives, unless they have been
disabled with
<blockquote>
<code>&lt;Directory /&gt;<br />
AllowOverride None<br />
&lt;/Directory&gt;</code>
</blockquote>
<p><strong>See Also:</strong> <a
href="#allowoverride">AllowOverride</a> and <a
href="../configuring.html">Configuration Files</a></p>
<hr />
<h2><a id="adddefaultcharset"
name="adddefaultcharset">AddDefaultCharset directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AddDefaultCharset
On|Off|<em>charset</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> all<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>AddDefaultCharset Off</code><br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a>
AddDefaultCharset is only available in Apache 1.3.12 and later
<p>This directive specifies the name of the character set that
will be added to any response that does not have any parameter
on the content type in the HTTP headers. This will override any
character set specified in the body of the document via a
<code>META</code> tag. A setting of <code>AddDefaultCharset
Off</code> disables this functionality. <code>AddDefaultCharset
On</code> enables Apache's internal default charset of
<code>iso-8859-1</code> as required by the directive. You can
also specify an alternate <em>charset</em> to be used.</p>
<p>For example:</p>
<blockquote>
<code>AddDefaultCharset utf-8</code>
</blockquote>
<p><b>Note:</b> This will <b>not</b> have any effect on the
Content-Type and character set for default Apache-generated
status pages (such as '404 Not Found' or '301 Moved Permanently')
because those have an <i>actual</i> character set (that in which the
hard-coded page content is written) and don't need to have a default
applied.</p>
<hr />
<h2><a id="addmodule" name="addmodule">AddModule
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AddModule
<em>module</em> [<em>module</em>] ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config <br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> AddModule is
only available in Apache 1.2 and later
<p>The server can have modules compiled in which are not
actively in use. This directive can be used to enable the use
of those modules. The server comes with a pre-loaded list of
active modules; this list can be cleared with the <a
href="#clearmodulelist">ClearModuleList</a> directive.</p>
<p>For example:</p>
<blockquote>
<code>AddModule mod_include.c</code>
</blockquote>
<p>The ordering of <code>AddModule</code> lines is important.
Modules are listed in reverse priority order --- the ones that come
later can override the behavior of those that come earlier. This
can have visible effects; for instance, if UserDir followed Alias,
you couldn't alias out a particular user's home directory. For
more information and a recommended ordering, see
<code>src/Configuration.tmpl</code> in the Apache source
distribution.</p>
<p><strong>See also</strong>: <a
href="#clearmodulelist">ClearModuleList</a> and <a
href="mod_so.html#loadmodule">LoadModule</a></p>
<hr />
<h2><a id="allowoverride" name="allowoverride">AllowOverride
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AllowOverride
All|None|<em>directive-type</em> [<em>directive-type</em>]
...<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>AllowOverride
All</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>When the server finds an .htaccess file (as specified by <a
href="#accessfilename">AccessFileName</a>) it needs to know
which directives declared in that file can override earlier
access information.</p>
<p><strong>Note:</strong> <code>AllowOverride</code> is only
valid in &lt;Directory&gt; sections, not in &lt;Location&gt; or
&lt;Files&gt; sections, as implied by the <strong>Context</strong>
section above.</p>
<p>When this directive is set to <code>None</code>, then
.htaccess files are completely ignored. In this case, the
server will not even attempt to read .htaccess files in the
filesystem.</p>
<p>When this directive is set to <code>All</code>, then any
directive which has the .htaccess <a
href="directive-dict.html#Context">Context</a> is allowed in
.htaccess files.</p>
<p>The <em>directive-type</em> can be one of the following
groupings of directives.</p>
<dl>
<dt>AuthConfig</dt>
<dd>
Allow use of the authorization directives (<a
href="mod_auth_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a>,
<a
href="mod_auth_dbm.html#authdbmuserfile">AuthDBMUserFile</a>,
<a href="mod_auth.html#authgroupfile">AuthGroupFile</a>, <a
href="#authname">AuthName</a>, <a
href="#AuthDigestRealmSeed">AuthDigestRealmSeed</a>, <a
href="#authtype">AuthType</a>, <a
href="mod_auth.html#authuserfile">AuthUserFile</a>, <a
href="#require">Require</a>, <em>etc.</em>).</dd>
<dt>FileInfo</dt>
<dd>
Allow use of the directives controlling document types (<a
href="mod_mime.html#addencoding">AddEncoding</a>, <a
href="mod_mime.html#addlanguage">AddLanguage</a>, <a
href="mod_mime.html#addtype">AddType</a>, <a
href="#defaulttype">DefaultType</a>, <a
href="#errordocument">ErrorDocument</a>, <a
href="mod_negotiation.html#languagepriority">LanguagePriority</a>,
<em>etc.</em>).</dd>
<dt>Indexes</dt>
<dd>
Allow use of the directives controlling directory indexing
(<a
href="mod_autoindex.html#adddescription">AddDescription</a>,
<a href="mod_autoindex.html#addicon">AddIcon</a>, <a
href="mod_autoindex.html#addiconbyencoding">AddIconByEncoding</a>,
<a href="mod_autoindex.html#addiconbytype">AddIconByType</a>,
<a href="mod_autoindex.html#defaulticon">DefaultIcon</a>, <a
href="mod_dir.html#directoryindex">DirectoryIndex</a>, <a
href="mod_autoindex.html#fancyindexing">FancyIndexing</a>, <a
href="mod_autoindex.html#headername">HeaderName</a>, <a
href="mod_autoindex.html#indexignore">IndexIgnore</a>, <a
href="mod_autoindex.html#indexoptions">IndexOptions</a>, <a
href="mod_autoindex.html#readmename">ReadmeName</a>,
<em>etc.</em>).</dd>
<dt>Limit</dt>
<dd>
Allow use of the directives controlling host access (<a
href="mod_access.html#allow">Allow</a>,
<a href="mod_access.html#deny">Deny</a>
and <a href="mod_access.html#order">Order</a>).</dd>
<dt>Options</dt>
<dd>
Allow use of the directives controlling specific directory
features (<a href="#options">Options</a> and <a
href="mod_include.html#xbithack">XBitHack</a>).</dd>
</dl>
<p>Example:</p>
<blockquote><code>AllowOverride AuthConfig Indexes</code></blockquote>
<p><strong>See Also:</strong> <a
href="#accessfilename">AccessFileName</a> and <a
href="../configuring.html">Configuration Files</a></p>
<hr />
<h2><a id="authname" name="authname">AuthName
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AuthName
<em>auth-domain</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory,
.htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> AuthConfig<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This directive sets the name of the authorization realm for
a directory. This realm is given to the client so that the user
knows which username and password to send.
<samp>AuthName</samp> takes a single argument; if the realm
name contains spaces, it must be enclosed in quotation marks.
It must be accompanied by <a href="#authtype">AuthType</a> and
<a href="#require">Require</a> directives, and directives such
as <a href="mod_auth.html#authuserfile">AuthUserFile</a> and <a
href="mod_auth.html#authgroupfile">AuthGroupFile</a> to
work.</p>
<p>For example:</p>
<blockquote><code>AuthName "Top Secret"</code></blockquote>
<p>The string provided for the <code>AuthName</code> is what will
appear in the password dialog provided by most browsers.</p>
<p><strong>See also:</strong> <a
href="../howto/auth.html">Authentication, Authorization, and
Access Control</a></p>
<hr />
<h2><a id="AuthDigestRealmSeed" name="AuthDigestRealmSeed">AuthDigestRealmSeed
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AuthDigestRealmSeed
<em>secret-real-string</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory,
.htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> AuthConfig<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This directive sets a per realm secret nonce prefix
which is used to ensure that a captured username, password
and realm string during a Digest exchange cannot
be replayed at other places.
</p>
<p>It only applies to <a href="mod_digest.html">mod_digest.html</a>,
the experimental <a href="mod_auth_digest.html">mod_auth_digest.html</a>
implements its own (more advanced and also time sensitive) replay protection.
</p>
It must be accompanied by <a href="#authtype">AuthType</a> of
type Digest, one or more
<a href="#require">Require</a> directives, and directives such
as <a href="mod_auth.html#authuserfile">AuthUserFile</a> and <a
href="mod_auth.html#authgroupfile">AuthGroupFile</a> to
work.</p>
<p><strong>See also:</strong> <a
href="../howto/auth.html">Authentication, Authorization, and
Access Control</a></p>
<hr />
<h2><a id="authtype" name="authtype">AuthType
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> AuthType
Basic|Digest<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory,
.htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> AuthConfig<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This directive selects the type of user authentication for a
directory. Only <code>Basic</code> and <code>Digest</code> are
currently implemented.
It must be accompanied by <a href="#authname">AuthName</a> and
<a href="#require">Require</a> directives, and directives such
as <a href="mod_auth.html#authuserfile">AuthUserFile</a> and <a
href="mod_auth.html#authgroupfile">AuthGroupFile</a> to
work.</p>
<p>When AuthDigest is used an <a href="#AuthDigestRealmSeed">AuthDigestRealmSeed</a>
should also be set.</p>
<p><strong>See also:</strong> <a
href="../howto/auth.html">Authentication, Authorization, and
Access Control</a></p>
<hr />
<h2><a id="bindaddress" name="bindaddress">BindAddress
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> BindAddress
*|<em>IP-address</em>|<em>domain-name</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>BindAddress
*</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> BindAddress is
deprecated and will be eliminated in Apache 2.0.
<p>A Unix&reg; http server can either listen for connections to
every IP address of the server machine, or just one IP address
of the server machine. If the argument to this directive is *,
then the server will listen for connections on every IP
address. Otherwise, the server can listen to only a specific
<em>IP-address</em> or a fully-qualified Internet
<em>domain-name</em>.</p>
<p>For example:</p>
<code>BindAddress 192.168.15.48</code><br />
<p>Only one <code>BindAddress</code> directive can be used.</p>
<p>This directive is deprecated and will be eliminated in
Apache 2.0. Equivalent functionality and more control over the
address and ports Apache listens to is available using the
<code><a href="#listen">Listen</a></code>
directive.</p>
<p><code>BindAddress</code> can be used as an alternative
method for supporting <a href="../vhosts/">virtual hosts</a>
using multiple independent servers, instead of using <code><a
href="#virtualhost">&lt;VirtualHost&gt;</a></code>
sections.</p>
<p><strong>See Also:</strong> <a href="../dns-caveats.html">DNS
Issues</a><br />
<strong>See Also:</strong> <a href="../bind.html">Setting
which addresses and ports Apache uses</a></p>
<hr />
<h2><a id="bs2000account" name="bs2000account">BS2000Account
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> BS2000Account
<em>account</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <em>none</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> BS2000Account is
only available for BS2000 machines, as of Apache 1.3 and later.
<p>The <code>BS2000Account</code> directive is available for
BS2000 hosts only. It must be used to define the account number
for the non-privileged apache server user (which was configured
using the <a href="#user">User</a> directive). This is required
by the BS2000 POSIX subsystem (to change the underlying BS2000
task environment by performing a sub-LOGON) to prevent CGI
scripts from accessing resources of the privileged account
which started the server, usually <samp>SYSROOT</samp>.<br />
Only one <code>BS2000Account</code> directive can be used.</p>
<p><strong>See Also:</strong> <a href="../ebcdic.html">Apache
EBCDIC port</a></p>
<hr />
<h2><a id="cgicommandargs" name="cgicommandargs">CGICommandArgs
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> CGICommandArgs On|Off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> CGICommandArgs On<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory, .htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> Options<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Available in Apache
1.3.24 and later.
<p>Way back when the internet was a safer, more naive place, it
was convenient for the server to take a query string that did not
contain an '=' sign and to parse and pass it to a CGI program as
command line args. For example, <code>&lt;IsIndex&gt;</code>
generated searches often work in this way. The default behavior
in Apache is to maintain this behavior for backwards
compatibility, although it is generally regarded as unsafe
practice today. Most CGI programs do not take command line
parameters, but among those that do, many are unaware of this
method of passing arguments and are therefore vulnerable to
malicious clients passing unsafe material in this way. Setting
<code>CGICommandArgs Off</code> is recommended to protect such
scripts with little loss in functionality.</p>
<hr />
<h2><a id="clearmodulelist"
name="clearmodulelist">ClearModuleList directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ClearModuleList<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ClearModuleList
is only available in Apache 1.2 and later
<p>The server comes with a built-in list of active modules.
This directive clears the list. It is assumed that the list
will then be re-populated using the <a
href="#addmodule">AddModule</a> directive.</p>
<p><strong>See also</strong>: <a
href="#addmodule">AddModule</a> and <a
href="mod_so.html#loadmodule">LoadModule</a></p>
<hr />
<h2><a id="contentdigest" name="contentdigest">ContentDigest
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ContentDigest
on|off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ContentDigest
off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> Options<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> experimental<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ContentDigest is
only available in Apache 1.1 and later
<p>This directive enables the generation of
<code>Content-MD5</code> headers as defined in RFC1864
respectively RFC2068.</p>
<p>MD5 is an algorithm for computing a "message digest"
(sometimes called "fingerprint") of arbitrary-length data, with
a high degree of confidence that any alterations in the data
will be reflected in alterations in the message digest.</p>
<p>The <code>Content-MD5</code> header provides an end-to-end
message integrity check (MIC) of the entity-body. A proxy or
client may check this header for detecting accidental
modification of the entity-body in transit. Example header:</p>
<pre>
Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
</pre>
<p>Note that this can cause performance problems on your server
since the message digest is computed on every request (the
values are not cached).</p>
<p><code>Content-MD5</code> is only sent for documents served
by the core, and not by any module. For example, SSI documents,
output from CGI scripts, and byte range responses do not have
this header.</p>
<hr />
<h2><a id="coredumpdirectory"
name="coredumpdirectory">CoreDumpDirectory directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> CoreDumpDirectory
<em>directory-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> the same location as
ServerRoot<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This controls the directory to which Apache attempts to
switch before dumping core. The default is in the <a
href="#serverroot">ServerRoot</a> directory, however since this
should not be writable by the user the server runs as, core
dumps won't normally get written. If you want a core dump for
debugging, you can use this directive to place it in a
different location.</p>
<p>For example:</p>
<blockquote>
<code>CoreDumpDirectory /tmp</code>
</blockquote>
<hr />
<h2><a id="defaulttype" name="defaulttype">DefaultType
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> DefaultType
<em>MIME-type</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>DefaultType
text/plain</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> FileInfo<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>There will be times when the server is asked to provide a
document whose type cannot be determined by its MIME types
mappings.</p>
<p>The server must inform the client of the content-type of the
document, so in the event of an unknown type it uses the
<code>DefaultType</code>. For example:</p>
<blockquote>
<code>DefaultType image/gif</code>
</blockquote>
would be appropriate for a directory which contained many gif
images with filenames missing the .gif extension.
<p><strong>See also:</strong> <a
href="mod_mime.html#addtype">AddType</a> and <a
href="mod_mime.html#typesconfig">TypesConfig</a>.</p>
<hr />
<h2><a id="directory" name="directory">&lt;Directory&gt;
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;Directory
<em>directory-path</em>|proxy:<em>url-path</em>&gt;
... &lt;/Directory&gt; <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core.
<p>&lt;Directory&gt; and &lt;/Directory&gt; are used to enclose
a group of directives which will apply only to the named
directory and sub-directories of that directory. Any directive
which is allowed in a directory context may be used.
<em>Directory-path</em> is either the full path to a directory,
or a wild-card string. In a wild-card string, `?' matches any
single character, and `*' matches any sequences of characters.
As of Apache 1.3, you may also use `[ ]' character ranges like
in the shell. Also as of Apache 1.3 none of the wildcards match
a `/' character, which more closely mimics the behavior of
Unix shells. Example:</p>
<pre>
&lt;Directory /usr/local/httpd/htdocs&gt;
Options Indexes FollowSymLinks
&lt;/Directory&gt;
</pre>
<p><strong>Apache 1.2 and above:</strong> Extended regular
expressions can also be used, with the addition of the
<code>~</code> character. For example:</p>
<pre>
&lt;Directory ~ "^/www/.*/[0-9]{3}"&gt;
</pre>
would match directories in /www/ that consisted of three
numbers.
<p>If multiple (non-regular expression) directory sections
match the directory (or its parents) containing a document,
then the directives are applied in the order of shortest match
first, interspersed with the directives from the <a
href="#accessfilename">.htaccess</a> files. For example,
with</p>
<blockquote>
<code>&lt;Directory /&gt;<br />
AllowOverride None<br />
&lt;/Directory&gt;<br />
<br />
&lt;Directory /home/*&gt;<br />
AllowOverride FileInfo<br />
&lt;/Directory&gt;</code>
</blockquote>
for access to the document <code>/home/web/dir/doc.html</code>
the steps are:
<ul>
<li>Apply directive <code>AllowOverride None</code>
(disabling <code>.htaccess</code> files).</li>
<li>Apply directive <code>AllowOverride FileInfo</code> (for
directory <code>/home/web</code>).</li>
<li>Apply any FileInfo directives in
<code>/home/web/.htaccess</code></li>
</ul>
<p>Regular expression directory sections are handled slightly
differently by Apache 1.2 and 1.3. In Apache 1.2 they are
interspersed with the normal directory sections and applied in
the order they appear in the configuration file. They are
applied only once, and apply when the shortest match possible
occurs. In Apache 1.3 regular expressions are not considered
until after all of the normal sections have been applied. Then
all of the regular expressions are tested in the order they
appeared in the configuration file. For example, with</p>
<blockquote>
<code>&lt;Directory ~ abc$&gt;<br />
... directives here ...<br />
&lt;/Directory&gt;<br />
</code>
</blockquote>
Suppose that the filename being accessed is
<code>/home/abc/public_html/abc/index.html</code>. The server
considers each of <code>/</code>, <code>/home</code>,
<code>/home/abc</code>, <code>/home/abc/public_html</code>, and
<code>/home/abc/public_html/abc</code> in that order. In Apache
1.2, when <code>/home/abc</code> is considered, the regular
expression will match and be applied. In Apache 1.3 the regular
expression isn't considered at all at that point in the tree.
It won't be considered until after all normal
&lt;Directory&gt;s and <code>.htaccess</code> files have been
applied. Then the regular expression will match on
<code>/home/abc/public_html/abc</code> and be applied.
<p><strong>Note that the default Apache access for
&lt;Directory /&gt; is <samp>Allow from All</samp>. This means
that Apache will serve any file mapped from an URL. It is
recommended that you change this with a block such
as</strong></p>
<pre>
&lt;Directory /&gt;
Order Deny,Allow
Deny from All
&lt;/Directory&gt;
</pre>
<p><strong>and then override this for directories you
<em>want</em> accessible. See the <a
href="../misc/security_tips.html">Security Tips</a> page for
more details.</strong></p>
&lt;Directory&gt; directives cannot nest, and cannot appear in
a <a href="#limit">&lt;Limit&gt;</a> or <a
href="#limitexcept">&lt;LimitExcept&gt;</a> section.
<p>If you have <a href="mod_proxy.html">mod_proxy</a> enabled, you
can use the <code>proxy:</code> syntax to apply configuration
directives to proxied content. The syntax for this is to specify the
proxied URLs to which you wish to apply the configuration, or to
specify <code>*</code> to apply to all proxied content:</p>
<p>To apply to all proxied content:</p>
<pre>
&lt;Directory proxy:*&gt;
... directives here ...
&lt;/Directory&gt;
</pre>
<p>To apply to just a subset of proxied content:</p>
<pre>
&lt;Directory proxy:http://www.example.com/&gt;
... directives here ...
&lt;/Directory&gt;
</pre>
<p><strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received</p>
<p><strong>See also</strong>: <a
href="#directorymatch">DirectoryMatch</a></p>
<hr />
<h2><a id="directorymatch"
name="directorymatch">&lt;DirectoryMatch&gt;</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;DirectoryMatch
<em>regex</em>&gt; ... &lt;/DirectoryMatch&gt; <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core.<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Available in
Apache 1.3 and later
<p>&lt;DirectoryMatch&gt; and &lt;/DirectoryMatch&gt; are used
to enclose a group of directives which will apply only to the
named directory and sub-directories of that directory, the same
as <a href="#directory">&lt;Directory&gt;</a>. However, it
takes as an argument a regular expression. For example:</p>
<pre>
&lt;DirectoryMatch "^/www/.*/[0-9]{3}"&gt;
</pre>
<p>would match directories in /www/ that consisted of three
numbers.</p>
<p><strong>See Also:</strong> <a
href="#directory">&lt;Directory&gt;</a> for a description of
how regular expressions are mixed in with normal
&lt;Directory&gt;s.<br />
<strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received</p>
<hr />
<h2><a id="documentroot" name="documentroot">DocumentRoot
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> DocumentRoot
<em>directory-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>DocumentRoot
/usr/local/apache/htdocs</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This directive sets the directory from which httpd will
serve files. Unless matched by a directive like Alias, the
server appends the path from the requested URL to the document
root to make the path to the document. Example:</p>
<blockquote>
<code>DocumentRoot /usr/web</code>
</blockquote>
then an access to
<code>http://www.my.host.com/index.html</code> refers to
<code>/usr/web/index.html</code>.
<p>There appears to be a bug in mod_dir which causes problems
when the DocumentRoot has a trailing slash (<em>i.e.</em>,
"DocumentRoot /usr/web/") so please avoid that.</p>
<hr />
<h2><a id="ebcdicconvert"
name="ebcdicconvert">EBCDICConvert</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> EBCDICConvert
On|Off[=<em>direction</em>] <em>extension</em>
[<em>extension</em>] ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> FileInfo<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> The configurable
EBCDIC conversion is only available in Apache 1.3.19 and later,
and on EBCDIC based platforms.
<p>The EBCDICConvert directive maps the given filename
extensions to the specified conversion setting (<samp>On</samp>
or <samp>Off</samp>). File extensions may be specified with or
without a leading dot.</p>
<p>If the optional format <samp>On=<i>direction</i></samp> (or
<samp>Off=<i>direction</i></samp>) is used, where
<i>direction</i> is one of <samp>In</samp>, <samp>Out</samp> or
<samp>InOut</samp>, then the directive only applies to the
specified transfer direction (<samp>In</samp>: uploaded content
in a PUT or POST request, <samp>Out</samp>: returned content in
a GET or POST request, and <samp>InOut</samp>: conversion in
both directions).<br />
Otherwise, <samp>InOut</samp> (conversion in both directions)
is implied.</p>
<p>Conversion configuration based on file extension is tested
prior to configuration based on MIME type, to allow for generic
MIME based rules to be overridden by a more specific file
extension (several file extensions may exist for the same MIME
type).</p>
<p><strong>Example</strong>:<br />
With a configuration like the following, the normal
<samp>*.html</samp> files contain HTML text in EBCDIC encoding,
while <samp>*.ahtml</samp> files contain HTML text in ASCII
encoding:</p>
<pre>
# *.html and *.ahtml contain HTML text:
AddType text/html .html .ahtml
# *.ahtml is not converted (contains ASCII text already):
EBCDICConvert Off .ahtml
# All other text/html files presumably contain EBCDIC text:
EBCDICConvertByType On text/html
</pre>
<br />
<br />
<p><strong>See also</strong>: <a
href="#ebcdicconvertbytype">EBCDICConvertByType</a> and <a
href="../ebcdic.html#ebcdic">Overview of the EBCDIC Conversion
Functions</a></p>
<hr />
<h2><a id="ebcdicconvertbytype"
name="ebcdicconvertbytype">EBCDICConvertByType</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> EBCDICConvertByType
On|Off[=<em>direction</em>] <em>mimetype</em>
[<em>mimetype</em>] ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> FileInfo<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> The configurable
EBCDIC conversion is only available in Apache 1.3.19 and later,
and on EBCDIC based platforms.
<p>The EBCDICConvertByType directive maps the given MIME type
(optionally containing wildcards) to the specified conversion
setting (<samp>On</samp> or <samp>Off</samp>).</p>
<p>If the optional format <samp>On=<i>direction</i></samp> (or
<samp>Off=<i>direction</i></samp>) is used, where
<i>direction</i> is one of <samp>In</samp>, <samp>Out</samp> or
<samp>InOut</samp>, then the directive only applies to the
specified transfer direction (<samp>In</samp>: uploaded content
in a PUT or POST request, <samp>Out</samp>: returned content in
a GET or POST request, and <samp>InOut</samp>: conversion in
both directions).<br />
Otherwise, <samp>InOut</samp> (conversion in both directions)
is implied.</p>
<p><strong>Example</strong>:<br />
A useful standard configuration should at least contain the
following defaults:</p>
<pre>
# All text documents are stored as EBCDIC files:
EBCDICConvertByType On text/* message/* multipart/*
EBCDICConvertByType On application/x-www-form-urlencoded \
model/vrml application/postscript
# All other files are assumed to be binary:
EBCDICConvertByType Off */*
</pre>
If you serve ASCII documents only, for example from an NFS
mounted unix server, use:
<pre>
# All documents are ASCII already:
EBCDICConvertByType Off */*
</pre>
<p><strong>See also</strong>: <a
href="#ebcdicconvert">EBCDICConvert</a> and <a
href="../ebcdic.html#ebcdic">Overview of the EBCDIC Conversion
Functions</a></p>
<hr />
<h2><a id="ebcdickludge"
name="ebcdickludge">EBCDICKludge</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> EBCDICKludge
On|Off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>EBCDICKludge
Off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> FileInfo<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> EBCDICKludge is
only available in Apache 1.3.19 and later, and on EBCDIC based
platforms. It is deprecated and will be withdrawn in a future
version.<br />
<p>The EBCDICKludge is provided for the backward compatible
behavior with apache versions 1.3.0 through 1.3.18. In these
versions, all files with MIME types starting with "text/",
"message/" or "multipart/" or with type
"application/x-www-form-urlencoded" would be converted by
default, all other documents were returned unconverted. Only if
a MIME type "<samp>text/<b>x-ascii-</b><i>subtype</i></samp>"
was configured for a certain document, the document was assumed
to be in ASCII format already, and was not converted again.
Instead, the "<samp><b>x-ascii-</b></samp>" was removed from
the type, resulting in the MIME type
"<samp>text/<i>subtype</i></samp>" being returned for the
document.</p>
<p>If the EBCDICKludge directive is set to <samp>On</samp>, and
if none of the file extensions configured with the <a
href="#ebcdicconvert">EBCDICConvert</a> directive matches in
the current context, then the server tests for a MIME type of
the format
<samp><i>type/</i><b>x-ascii-</b><i>subtype</i></samp>. If the
document has such a type, then the
"<samp><b>x-ascii-</b></samp>" substring is removed and the
conversion set to <samp>Off</samp>. This allows for overriding
the implicit assumption that all text files are stored in
EBCDIC format, for example when serving documents from an NFS
mounted directory with ASCII documents.<br />
By using the EBCDICKludge, there is no way to force one of the
other MIME types (<em>e.g.</em>, model/vrml) to be treated as
an EBCDIC text file. Use of the <a
href="#ebcdicconvertbytype">EBCDICConvertByType</a> directive
mentioned above is the preferred way to configure such a
conversion. (Before Apache version 1.3.19, there was no way at
all to force these binary documents to be treated as EBCDIC
text files.)</p>
<p><strong>See also</strong>: <a
href="#ebcdicconvert">EBCDICConvert</a>, <a
href="#ebcdicconvertbytype">EBCDICConvertByType</a> and <a
href="../ebcdic.html#ebcdic">Overview of the EBCDIC Conversion
Functions</a></p>
<hr />
<h2><a id="enableexceptionhook" name="enableexceptionhook">
EnableExceptionHook directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> EnableExceptionHook
on|off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>EnableExceptionHook
off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> EnableExceptionHook
is available in Apache 1.3.30 and later
<p><code>EnableExceptionHook</code> controls whether or not an
exception hook implemented by a module will be called after a
child process crash. The exception hook allows modules to log
diagnostic information that may help determine the cause of the
crash.</p>
<hr />
<h2><a id="errordocument" name="errordocument">ErrorDocument
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ErrorDocument
<em>error-code document</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> FileInfo<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> The directory
and .htaccess contexts are only available in Apache 1.1 and
later.
<p>In the event of a problem or error, Apache can be configured
to do one of four things,</p>
<ol>
<li>output a simple hardcoded error message</li>
<li>output a customized message</li>
<li>redirect to a local <em>URL-path</em> to handle the
problem/error</li>
<li>redirect to an external <em>URL</em> to handle the
problem/error</li>
</ol>
<p>The first option is the default, while options 2-4 are
configured using the <code>ErrorDocument</code> directive,
which is followed by the HTTP response code and a message or
URL.</p>
<p><em>Messages</em> in this context begin with a single
double-quote character (<code>"</code>), which does not form
part of the message itself. Apache will sometimes offer
additional information regarding the problem/error.</p>
<p>URLs can begin with a slash (/) for local URLs, or be a full
URL which the client can resolve. Examples:</p>
<blockquote>
<code>ErrorDocument 500
http://foo.example.com/cgi-bin/tester<br />
ErrorDocument 404 /cgi-bin/bad_urls.pl<br />
ErrorDocument 401 /subscription_info.html<br />
ErrorDocument 403 "Sorry can't allow you access today</code>
</blockquote>
<p>Note that when you specify an <code>ErrorDocument</code>
that points to a remote URL (ie. anything with a method such as
"http" in front of it), Apache will send a redirect to the
client to tell it where to find the document, even if the
document ends up being on the same server. This has several
implications, the most important being that the client will not
receive the original error status code, but instead will
receive a redirect status code. This in turn can confuse web
robots and other clients which try to determine if a URL is
valid using the status code. In addition, if you use a remote
URL in an <code>ErrorDocument 401</code>, the client will not
know to prompt the user for a password since it will not
receive the 401 status code. Therefore, <strong>if you use an
"ErrorDocument 401" directive then it must refer to a local
document.</strong></p>
<p>Microsoft Internet Explorer (MSIE) will by default ignore
server-generated error messages when they are "too small" and substitute
its own "friendly" error messages. The size threshold varies depending on
the type of error, but in general, if you make your error document
greater than 512 bytes, then MSIE will show the server-generated
error rather than masking it. More information is available in
Microsoft Knowledgebase article <a
href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807"
>Q294807</a>.</p>
<p>See Also: <a href="../custom-error.html">documentation of
customizable responses.</a> See the <a
href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html">HTTP
specification</a> for a complete list of the status codes and their
meanings.</p>
<hr />
<h2><a id="errorlog" name="errorlog">ErrorLog
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ErrorLog
<em>file-path</em>|syslog[:<em>facility</em>] <br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ErrorLog
logs/error_log</code> (Unix)<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ErrorLog
logs/error.log</code> (Windows and OS/2)<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The error log directive sets the name of the file to which
the server will log any errors it encounters. If the
<em>file-path</em> does not begin with a slash (/) then it is
assumed to be relative to the <a
href="#serverroot">ServerRoot</a>. If the <em>file-path</em>
begins with a pipe (|) then it is assumed to be a command to
spawn to handle the error log.</p>
<p>Examples</p>
<p><code>ErrorLog logs/vhost1.error</code></p>
or
<p><code>ErrorLog |/usr/local/bin/errorlog.pl</code></p>
<p><strong>Apache 1.3 and above:</strong> Using
<code>syslog</code> instead of a filename enables logging via
syslogd(8) if the system supports it. The default is to use
syslog facility <code>local7</code>, but you can override this
by using the <code>syslog:</code><em>facility</em> syntax where
<em>facility</em> can be one of the names usually documented in
syslog(1).</p>
<p>For example:</p>
<p><code>ErrorLog syslog</code></p>
or
<p><code>ErrorLog syslog:user</code></p>
<p>SECURITY: See the <a
href="../misc/security_tips.html#serverroot">security tips</a>
document for details on why your security could be compromised
if the directory where logfiles are stored is writable by
anyone other than the user that starts the server.</p>
<p><strong>See also:</strong> <a href="#loglevel">LogLevel</a>
and <a href="../logs.html">Apache Log Files</a></p>
<hr />
<h2><a id="fileetag" name="fileetag">FileETag directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> FileETag
<i>component</i> ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> FileInfo<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> only available
in Apache 1.3.23 versions and later.
<p>
The FileETag directive configures the file attributes that are
used to create the ETag (entity tag) response header field
when the document is based on a file.
(The ETag value is used in cache management to save network
bandwidth.) In Apache 1.3.22 and earlier, the ETag value was
<i>always</i> formed from the file's inode, size, and last-modified
time (mtime). The FileETag directive allows you to choose
which of these -- if any -- should be used. The recognized
keywords are:
</p>
<dl compact="compact">
<dt><b>INode</b></dt>
<dd>The file's i-node number will be included in the calculation</dd>
<dt><b>MTime</b></dt>
<dd>The date and time the file was last modified will be included</dd>
<dt><b>Size</b></dt>
<dd>The number of bytes in the file will be included</dd>
<dt><b>All</b></dt>
<dd>All available fields will be used (equivalent to
'<code>FileETag&nbsp;INode&nbsp;MTime&nbsp;Size</code>')</dd>
<dt><b>None</b></dt>
<dd>If a document is file-based, no ETag field will be included in the
response</dd>
</dl>
<p>
The INode, MTime, and Size keywords may be prefixed with either '+'
or '-', which allow changes to be made to the default setting
inherited from a broader scope. Any keyword appearing without
such a prefix immediately and completely cancels the inherited
setting.
</p>
<p>
If a directory's configuration includes
'<code>FileETag&nbsp;INode&nbsp;MTime&nbsp;Size</code>', and a
subdirectory's includes '<code>FileETag&nbsp;-INode</code>',
the setting for that subdirectory (which will be inherited by
any sub-subdirectories that don't override it) will be equivalent to
'<code>FileETag&nbsp;MTime&nbsp;Size</code>'.
</p>
<hr />
<h2><a id="files" name="files">&lt;Files&gt; directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;Files
<em>filename</em>&gt; ... &lt;/Files&gt;<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> only available
in Apache 1.2 and above.
<p>The &lt;Files&gt; directive provides for access control by
filename. It is comparable to the <a
href="#directory">&lt;Directory&gt;</a> directive and <a
href="#location">&lt;Location&gt;</a> directives. It should be
matched with a &lt;/Files&gt; directive. The directives given
within this section will be applied to any object with a
basename (last component of filename) matching the specified
filename. <code>&lt;Files&gt;</code> sections are processed in
the order they appear in the configuration file, after the
&lt;Directory&gt; sections and <code>.htaccess</code> files are
read, but before &lt;Location&gt; sections. Note that
&lt;Files&gt; can be nested inside &lt;Directory&gt; sections
to restrict the portion of the filesystem they apply to.</p>
<p>The <em>filename</em> argument should include a filename, or
a wild-card string, where `?' matches any single character, and
`*' matches any sequences of characters. Extended regular
expressions can also be used, with the addition of the
<code>~</code> character. For example:</p>
<pre>
&lt;Files ~ "\.(gif|jpe?g|png)$"&gt;
</pre>
would match most common Internet graphics formats. In Apache
1.3 and later, <a href="#filesmatch">&lt;FilesMatch&gt;</a> is
preferred, however.
<p>Note that unlike <a
href="#directory"><code>&lt;Directory&gt;</code></a> and <a
href="#location"><code>&lt;Location&gt;</code></a> sections,
<code>&lt;Files&gt;</code> sections can be used inside
.htaccess files. This allows users to control access to their
own files, at a file-by-file level.
For example, to password protect a single file within a
particular directory, you might add the following to your
<code>.htaccess</code> file:</p>
<pre>
&lt;Files admin.cgi&gt;
Require group admin
&lt;/Files&gt;</pre>
<p>Remember that directives apply to subdirectories as well, so this
will also protect files called <code>admin.cgi</code> in
subdirectories, unless specifically overridden.</p>
<p>(See <a href="#require">Require</a> for details on using the
<code>Require</code> directive)</p>
<p><strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received</p>
<hr />
<h2><a id="filesmatch"
name="filesmatch">&lt;FilesMatch&gt;</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;FilesMatch
<em>regex</em>&gt; ... &lt;/FilesMatch&gt;<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> only available
in Apache 1.3 and above.
<p>The &lt;FilesMatch&gt; directive provides for access control
by filename, just as the <a href="#files">&lt;Files&gt;</a>
directive does. However, it accepts a regular expression. For
example:</p>
<pre>
&lt;FilesMatch "\.(gif|jpe?g|png)$"&gt;
</pre>
<p>would match most common Internet graphics formats.</p>
<strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received
<hr />
<h2><a id="group" name="group">Group directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Group
<em>unix-group</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>Group
#-1</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The Group directive sets the group under which the server
will answer requests. In order to use this directive, the
stand-alone server must be run initially as root.
<em>Unix-group</em> is one of:</p>
<dl>
<dt>A group name</dt>
<dd>Refers to the given group by name.</dd>
<dt># followed by a group number.</dt>
<dd>Refers to a group by its number.</dd>
</dl>
<p>It is recommended that you set up a new group specifically for
running the server. Some admins use user <code>nobody</code>,
but this is not always possible or desirable.</p>
<p>Example:</p>
<code>Group www-group</code>
<p>Note: if you start the server as a non-root user, it will
fail to change to the specified group, and will instead
continue to run as the group of the original user.</p>
<p>Special note: Use of this directive in &lt;VirtualHost&gt;
requires a properly configured <a href="../suexec.html">suEXEC
wrapper</a>. When used inside a &lt;VirtualHost&gt; in this
manner, only the group that CGIs are run as is affected.
Non-CGI requests are still processed as the group specified in
the main Group directive.</p>
<p>SECURITY: See <a href="#user">User</a> for a discussion of
the security considerations.</p>
<hr />
<h2><a id="hostnamelookups"
name="hostnamelookups">HostnameLookups directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> HostnameLookups
on|off|double<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>HostnameLookups
off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a>
<code>double</code> available only in Apache 1.3 and
above.<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Default was
<code>on</code> prior to Apache 1.3.
<p>This directive enables DNS lookups so that host names can be
logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
The value <code>double</code> refers to doing double-reverse
DNS. That is, after a reverse lookup is performed, a forward
lookup is then performed on that result. At least one of the ip
addresses in the forward lookup must match the original
address. (In "tcpwrappers" terminology this is called
<code>PARANOID</code>.)</p>
<p>Regardless of the setting, when <a
href="mod_access.html">mod_access</a> is used for controlling
access by hostname, a double reverse lookup will be performed.
This is necessary for security. Note that the result of this
double-reverse isn't generally available unless you set
<code>HostnameLookups double</code>. For example, if only
<code>HostnameLookups on</code> and a request is made to an
object that is protected by hostname restrictions, regardless
of whether the double-reverse fails or not, CGIs will still be
passed the single-reverse result in
<code>REMOTE_HOST</code>.</p>
<p>The default for this directive was previously
<code>on</code> in versions of Apache prior to 1.3. It was
changed to <code>off</code> in order to save the network
traffic for those sites that don't truly need the reverse
lookups done. It is also better for the end users because they
don't have to suffer the extra latency that a lookup entails.
Heavily loaded sites should leave this directive
<code>off</code>, since DNS lookups can take considerable
amounts of time. The utility <a
href="../programs/logresolve.html">logresolve</a>, provided in
the <em>/support</em> directory, can be used to look up host
names from logged IP addresses offline.</p>
<hr />
<h2><a id="identitycheck" name="identitycheck">IdentityCheck
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> IdentityCheck
on|off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>IdentityCheck
off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This directive enables RFC1413-compliant logging of the
remote user name for each connection, where the client machine
runs identd or something similar. This information is logged in
the access log.</p>
<p>The information should not be trusted in any way except for
rudimentary usage tracking.</p>
<p>Note that this can cause serious latency problems accessing
your server since every request requires one of these lookups
to be performed. When firewalls are involved each lookup might
possibly fail and add 30 seconds of latency to each hit. So in
general this is not very useful on public servers accessible
from the Internet.</p>
<hr />
<h2><a id="ifdefine" name="ifdefine">&lt;IfDefine&gt;
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;IfDefine
[!]<em>parameter-name</em>&gt; <em>...</em>
&lt;/IfDefine&gt;<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> None<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> all<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> &lt;IfDefine&gt;
is only available in 1.3.1 and later.
<p>The &lt;IfDefine <em>test</em>&gt;...&lt;/IfDefine&gt;
section is used to mark directives that are conditional. The
directives within an IfDefine section are only processed if the
<em>test</em> is true. If <em>test</em> is false, everything
between the start and end markers is ignored.</p>
<p>The <em>test</em> in the &lt;IfDefine&gt; section directive
can be one of two forms:</p>
<ul>
<li><em>parameter-name</em></li>
<li><code>!</code><em>parameter-name</em></li>
</ul>
<p>In the former case, the directives between the start and end
markers are only processed if the parameter named
<em>parameter-name</em> is defined. The second format reverses
the test, and only processes the directives if
<em>parameter-name</em> is <strong>not</strong> defined.</p>
<p>The <em>parameter-name</em> argument is a define as given on
the <code>httpd</code> command line via
<code>-D</code><em>parameter-</em>, at the time the server was
started.</p>
<p>&lt;IfDefine&gt; sections are nest-able, which can be used
to implement simple multiple-parameter tests. Example:</p>
<pre>
$ httpd -DReverseProxy ...
# httpd.conf
&lt;IfDefine ReverseProxy&gt;
LoadModule rewrite_module libexec/mod_rewrite.so
LoadModule proxy_module libexec/libproxy.so
&lt;/IfDefine&gt;
</pre>
<hr />
<h2><a id="ifmodule" name="ifmodule">&lt;IfModule&gt;
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;IfModule
[!]<em>module-name</em>&gt; <em>...</em>
&lt;/IfModule&gt;<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> None<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> all<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> IfModule is only
available in 1.2 and later.
<p>The &lt;IfModule <em>test</em>&gt;...&lt;/IfModule&gt;
section is used to mark directives that are conditional. The
directives within an IfModule section are only processed if the
<em>test</em> is true. If <em>test</em> is false, everything
between the start and end markers is ignored.</p>
<p>The <em>test</em> in the &lt;IfModule&gt; section directive
can be one of two forms:</p>
<ul>
<li><em>module name</em></li>
<li>!<em>module name</em></li>
</ul>
<p>In the former case, the directives between the start and end
markers are only processed if the module named <em>module
name</em> is included in Apache -- either compiled in or
dynamically loaded using <a
href="mod_so.html#loadmodule">LoadModule</a>. The second format
reverses the test, and only processes the directives if <em>module
name</em> is <strong>not</strong> included.</p>
<p>The <em>module name</em> argument is the file name of the
module, at the time it was compiled.
For example, <code>mod_rewrite.c</code>.</p>
<p>&lt;IfModule&gt; sections are nest-able, which can be used
to implement simple multiple-module tests.</p>
<hr />
<h2><a id="include" name="include">Include directive</a></h2>
<strong>Syntax:</strong> Include
<em>file-path</em>|<em>directory-path</em>|<em>wildcard-path</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Include is only
available in Apache 1.3 and later. Wildcards were introduced in
version 1.3.27.
<p>This directive allows inclusion of other configuration files
from within the server configuration files.</p>
<p>The file path specified may be a fully qualified path (i.e.
starting with a slash), or may be relative to the
<code>ServerRoot</code> directory.</p>
<p>New in Apache 1.3.13 is the feature that if
<code>Include</code> points to a directory, rather than a file,
Apache will read all files in that directory, and any
subdirectory, and parse those as configuration files.</p>
<p>By using a wildcard this can be further limited to, say,
just the '*.conf' files.
</p>
<p>Examples:</p>
<blockquote>
<code>Include /usr/local/apache/conf/ssl.conf<br />
Include /usr/local/apache/conf/vhosts/
</code>
</blockquote>
<p>Or, providing paths relative to your <code>ServerRoot</code>
directory:</p>
<blockquote>
<code>Include conf/ssl.conf<br />
Include conf/vhosts/
</code>
</blockquote>
<p>Make sure that an included directory does not contain any stray
files, such as editor temporary files, for example, as Apache will
attempt to read them in and use the contents as configuration
directives, which may cause the server to fail on start up.
Running <code>apachectl configtest</code> will give you a list of
the files that are being processed during the configuration
check:</p>
<pre>
root@host# apachectl configtest
Processing config directory: /usr/local/apache/conf/vhosts
Processing config file: /usr/local/apache/conf/vhosts/vhost1
Processing config file: /usr/local/apache/conf/vhosts/vhost2
Syntax OK
</pre>
<p>This will help in verifying that you are getting only the files
that you intended as part of your configuration.</p>
<p><strong>See also</strong>: <a
href="../programs/apachectl.html">apachectl</a></p>
<hr />
<h2><a id="keepalive" name="keepalive">KeepAlive
directive</a></h2>
<strong>Syntax: (Apache 1.1)</strong> KeepAlive
<em>max-requests</em><br />
<strong>Default: (Apache 1.1)</strong> <code>KeepAlive
5</code><br />
<strong>Syntax: (Apache 1.2)</strong> KeepAlive on|off<br />
<strong>Default: (Apache 1.2)</strong> <code>KeepAlive
On</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> KeepAlive is
only available in Apache 1.1 and later.
<p>The Keep-Alive extension to HTTP/1.0 and the persistent
connection feature of HTTP/1.1 provide long-lived HTTP sessions
which allow multiple requests to be sent over the same TCP
connection. In some cases this has been shown to result in an
almost 50% speedup in latency times for HTML documents with
many images. To enable Keep-Alive connections in Apache 1.2 and
later, set <code>KeepAlive On</code>.</p>
<p>For HTTP/1.0 clients, Keep-Alive connections will only be
used if they are specifically requested by a client. In
addition, a Keep-Alive connection with an HTTP/1.0 client can
only be used when the length of the content is known in
advance. This implies that dynamic content such as CGI output,
SSI pages, and server-generated directory listings will
generally not use Keep-Alive connections to HTTP/1.0 clients.
For HTTP/1.1 clients, persistent connections are the default
unless otherwise specified. If the client requests it, chunked
encoding will be used in order to send content of unknown
length over persistent connections.</p>
<p><strong>Apache 1.1 only</strong>: Set <em>max-requests</em>
to the maximum number of requests you want Apache to entertain
per connection. A limit is imposed to prevent a client from
hogging your server resources. Set this to <code>0</code> to
disable support. In Apache 1.2 and 1.3, this is controlled
through the MaxKeepAliveRequests directive instead.</p>
<p>See also <a
href="#maxkeepaliverequests">MaxKeepAliveRequests</a>.</p>
<hr />
<h2><a id="keepalivetimeout"
name="keepalivetimeout">KeepAliveTimeout directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> KeepAliveTimeout
<em>seconds</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>KeepAliveTimeout
15</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> KeepAliveTimeout
is only available in Apache 1.1 and later.
<p>The number of seconds Apache will wait for a subsequent
request before closing the connection. Once a request has been
received, the timeout value specified by the <a
href="#timeout"><code>Timeout</code></a> directive applies.</p>
<p>Setting <code>KeepAliveTimeout</code> to a high value may
cause performance problems in heavily loaded servers. The
higher the timeout, the more server processes will be kept
occupied waiting on connections with idle clients.</p>
<hr />
<h2><a id="limit" name="limit">&lt;Limit&gt; directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;Limit
<em>method</em> [<em>method</em>] ... &gt; ...
&lt;/Limit&gt;<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> any<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>Access controls are normally effective for
<strong>all</strong> access methods, and this is the usual
desired behavior. <strong>In the general case, access control
directives should not be placed within a
<code>&lt;limit&gt;</code> section.</strong></p>
<p>The purpose of the &lt;Limit&gt; directive is to restrict
the effect of the access controls to the nominated HTTP
methods. For all other methods, the access restrictions that
are enclosed in the &lt;Limit&gt; bracket <strong>will have no
effect</strong>. The following example applies the access
control only to the methods POST, PUT, and DELETE, leaving all
other methods unprotected:</p>
<blockquote>
<code>&lt;Limit POST PUT DELETE&gt;<br />
Require valid-user<br />
&lt;/Limit&gt;</code>
</blockquote>
<p>The method names listed can be one or more of: GET, POST, PUT,
DELETE, CONNECT, OPTIONS, PATCH, PROPFIND, PROPPATCH,
MKCOL, COPY, MOVE, LOCK, and UNLOCK. <strong>The method name is
case-sensitive.</strong> If GET is used it will also restrict
HEAD requests. The TRACE method cannot be limited.</p>
<p><strong>Warning:</strong> A <a
href="#limitexcept">&lt;LimitExcept&gt;</a> section should
always be used in preference to a <a
href="#limit">&lt;Limit&gt;</a> section when restricting access,
since a <a href="#limitexcept">&lt;LimitExcept&gt;</a> section
provides protection against arbitrary methods.</p>
<hr />
<h2><a id="limitexcept" name="limitexcept">&lt;LimitExcept&gt;
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;LimitExcept
<em>method</em> [<em>method</em>] ... &gt; ...
&lt;/LimitExcept&gt;<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> any<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Available in
Apache 1.3.5 and later
<p>&lt;LimitExcept&gt; and &lt;/LimitExcept&gt; are used to
enclose a group of access control directives which will then
apply to any HTTP access method <strong>not</strong> listed in
the arguments; <em>i.e.</em>, it is the opposite of a <a
href="#limit">&lt;Limit&gt;</a> section and can be used to
control both standard and nonstandard/unrecognized methods. See
the documentation for <a href="#limit">&lt;Limit&gt;</a> for
more details.</p>
<p>For example:</p>
<pre>
&lt;LimitExcept POST GET&gt;
Require valid-user
&lt;/LimitExcept&gt;
</pre>
<hr />
<h2><a id="limitinternalrecursion"
name="limitinternalrecursion">LimitInternalRecursion directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LimitInternalRecursion
<em>number</em> [<em>number</em>]<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>LimitInternalRecursion
20</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> LimitInternalRecursion
is only available in Apache 1.3.28 and later.
<p>An internal redirect happens, for example, when using the <a
href="mod_actions.html#action">Action</a> directive, which internally
redirects the original request to a CGI script. A subrequest is Apache's
mechanism to find out what would happen for some URI if it were requested.
For example, <a href="mod_dir.html">mod_dir</a> uses subrequests to look
for the files listed in the <a
href="mod_dir.html#directoryindex">DirectoryIndex</a>
directive.</p>
<p><code>LimitInternalRecursion</code> prevents the server
from crashing when entering an infinite loop of internal redirects or
subrequests. Such loops are usually caused by misconfigurations.</p>
<p>The directive stores two different limits, which are evaluated on
per-request basis. The first <em>number</em> is the maximum number of
internal redirects, that may follow each other. The second <em>number</em>
determines, how deep subrequests may be nested. If you specify only one
<em>number</em>, it will be assigned to both limits. A value of
<code>0</code> means "unlimited".</p>
<p><strong>Example</strong></p>
<pre>
LimitInternalRecursion 5
</pre>
<hr />
<h2><a id="limitrequestbody"
name="limitrequestbody">LimitRequestBody directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LimitRequestBody
<em>bytes</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>LimitRequestBody
0</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> LimitRequestBody
is only available in Apache 1.3.2 and later.
<p>This directive specifies the number of <em>bytes</em> from 0
(meaning unlimited) to 2147483647 (2GB) that are allowed in a
request body.</p>
<p>The LimitRequestBody directive allows the user to set a
limit on the allowed size of an HTTP request message body
within the context in which the directive is given (server,
per-directory, per-file or per-location). If the client request
exceeds that limit, the server will return an error response
instead of servicing the request. The size of a normal request
message body will vary greatly depending on the nature of the
resource and the methods allowed on that resource. CGI scripts
typically use the message body for passing form information to
the server. Implementations of the PUT method will require a
value at least as large as any representation that the server
wishes to accept for that resource.</p>
<p>This directive gives the server administrator greater
control over abnormal client request behavior, which may be
useful for avoiding some forms of denial-of-service
attacks.</p>
<p>If, for example, you are permitting file upload to a particular
location, and wich to limit the size of the uploaded file to 100K,
you might use the following directive:</p>
<pre>LimitRequestBody 102400</pre>
<hr />
<h2><a id="limitrequestfields"
name="limitrequestfields">LimitRequestFields directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LimitRequestFields
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>LimitRequestFields 100</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a>
LimitRequestFields is only available in Apache 1.3.2 and later.
<p><em>Number</em> is an integer from 0 (meaning unlimited) to
32767. The default value is defined by the compile-time
constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
distributed).</p>
<p>The LimitRequestFields directive allows the server
administrator to modify the limit on the number of request
header fields allowed in an HTTP request. A server needs this
value to be larger than the number of fields that a normal
client request might include. The number of request header
fields used by a client rarely exceeds 20, but this may vary
among different client implementations, often depending upon
the extent to which a user has configured their browser to
support detailed content negotiation. Optional HTTP extensions
are often expressed using request header fields.</p>
<p>This directive gives the server administrator greater
control over abnormal client request behavior, which may be
useful for avoiding some forms of denial-of-service attacks.
The value should be increased if normal clients see an error
response from the server that indicates too many fields were
sent in the request.</p>
<p>For example:</p>
<pre>LimitRequestFields 50</pre>
<hr />
<h2><a id="limitrequestfieldsize"
name="limitrequestfieldsize">LimitRequestFieldsize
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LimitRequestFieldsize
<em>bytes</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>LimitRequestFieldsize 8190</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a>
LimitRequestFieldsize is only available in Apache 1.3.2 and
later.
<p>This directive specifies the number of <em>bytes</em> from 0
to the value of the compile-time constant
<code>DEFAULT_LIMIT_REQUEST_FIELDSIZE</code> (8190 as
distributed) that will be allowed in an HTTP request
header.</p>
<p>The LimitRequestFieldsize directive allows the server
administrator to reduce the limit on the allowed size of an
HTTP request header field below the normal input buffer size
compiled with the server. A server needs this value to be large
enough to hold any one header field from a normal client
request. The size of a normal request header field will vary
greatly among different client implementations, often depending
upon the extent to which a user has configured their browser to
support detailed content negotiation.</p>
<p>This directive gives the server administrator greater
control over abnormal client request behavior, which may be
useful for avoiding some forms of denial-of-service attacks.</p>
<p>For example:</p>
<pre>LimitRequestFieldSize 16380</pre>
<p>Under normal conditions, the value should not be changed from
the default.</p>
<hr />
<h2><a id="limitrequestline"
name="limitrequestline">LimitRequestLine directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LimitRequestLine
<em>bytes</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>LimitRequestLine
8190</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> LimitRequestLine
is only available in Apache 1.3.2 and later.
<p>This directive sets the number of <em>bytes</em> from 0 to
the value of the compile-time constant
<code>DEFAULT_LIMIT_REQUEST_LINE</code> (8190 as distributed)
that will be allowed on the HTTP request-line.</p>
<p>The LimitRequestLine directive allows the server
administrator to reduce the limit on the allowed size of a
client's HTTP request-line below the normal input buffer size
compiled with the server. Since the request-line consists of
the HTTP method, URI, and protocol version, the
LimitRequestLine directive places a restriction on the length
of a request-URI allowed for a request on the server. A server
needs this value to be large enough to hold any of its resource
names, including any information that might be passed in the
query part of a GET request.</p>
<p>This directive gives the server administrator greater
control over abnormal client request behavior, which may be
useful for avoiding some forms of denial-of-service attacks.</p>
<p>For example:</p>
<pre>LimitRequestLine 16380</pre>
<p>Under normal conditions, the value should not be changed from
the default.</p>
<hr />
<h2><a id="listen" name="listen">Listen directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Listen
[<em>IP-address</em>:]<em>port</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Listen is only
available in Apache 1.1 and later.
<p>The Listen directive instructs Apache to listen to more than
one IP address or port; by default it responds to requests on
all IP interfaces, but only on the port given by the <code><a
href="#port">Port</a></code> directive.</p>
<tt>Listen</tt> can be used instead of <tt><a
href="#bindaddress">BindAddress</a></tt> and <tt>Port</tt>. It
tells the server to accept incoming requests on the specified
port or address-and-port combination. If the first format is
used, with a port number only, the server listens to the given
port on all interfaces, instead of the port given by the
<tt>Port</tt> directive. If an IP address is given as well as a
port, the server will listen on the given port and interface.
<p>Note that you may still require a <tt>Port</tt> directive so
that URLs that Apache generates that point to your server still
work.</p>
<p>Multiple Listen directives may be used to specify a number
of addresses and ports to listen to. The server will respond to
requests from any of the listed addresses and ports.</p>
<p>For example, to make the server accept connections on both
port 80 and port 8000, use:</p>
<pre>
Listen 80
Listen 8000
</pre>
To make the server accept connections on two specified
interfaces and port numbers, use
<pre>
Listen 192.170.2.1:80
Listen 192.170.2.5:8000
</pre>
<p><strong>See Also:</strong> <a href="../dns-caveats.html">DNS
Issues</a><br />
<strong>See Also:</strong> <a href="../bind.html">Setting
which addresses and ports Apache uses</a><br />
<strong>See Also:</strong> <a
href="http://httpd.apache.org/info/known_bugs.html#listenbug">Known
Bugs</a></p>
<hr />
<h2><a id="listenbacklog" name="listenbacklog">ListenBacklog
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ListenBacklog
<em>backlog</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ListenBacklog
511</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ListenBacklog is
only available in Apache versions after 1.2.0.
<p>The maximum length of the queue of pending connections.
Generally no tuning is needed or desired, however on some
systems it is desirable to increase this when under a TCP SYN
flood attack. See the backlog parameter to the
<code>listen(2)</code> system call.</p>
<p>This will often be limited to a smaller number by the
operating system. This varies from OS to OS. Also note that
many OSes do not use exactly what is specified as the backlog,
but use a number based on (but normally larger than) what is
set.</p>
<hr />
<h2><a id="location" name="location">&lt;Location&gt;
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;Location
<em>URL-path</em>|<em>URL</em>&gt; ... &lt;/Location&gt;<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Location is only
available in Apache 1.1 and later.
<p>The &lt;Location&gt; directive provides for access control
by URL. It is similar to the <a
href="#directory">&lt;Directory&gt;</a> directive, and starts a
subsection which is terminated with a &lt;/Location&gt;
directive. <code>&lt;Location&gt;</code> sections are processed
in the order they appear in the configuration file, after the
&lt;Directory&gt; sections and <code>.htaccess</code> files are
read, and after the &lt;Files&gt; sections.</p>
<p>Note that URLs do not have to line up with the filesystem at
all, it should be emphasized that &lt;Location&gt; operates
completely outside the filesystem.</p>
<p>For all origin (non-proxy) requests, the URL to be matched
is of the form <code>/path/</code>, and you should not include
any <code>http://servername</code> prefix. For proxy requests,
the URL to be matched is of the form
<code>scheme://servername/path</code>, and you must include the
prefix.</p>
<p>The URL may use wildcards In a wild-card string, `?' matches
any single character, and `*' matches any sequences of
characters.</p>
<p><strong>Apache 1.2 and above:</strong> Extended regular
expressions can also be used, with the addition of the
<code>~</code> character. For example:</p>
<pre>
&lt;Location ~ "/(extra|special)/data"&gt;
</pre>
<p>would match URLs that contained the substring "/extra/data"
or "/special/data". In Apache 1.3 and above, a new directive <a
href="#locationmatch">&lt;LocationMatch&gt;</a> exists which
behaves identical to the regex version of
<code>&lt;Location&gt;</code>.</p>
<p>The <code>Location</code> functionality is especially useful
when combined with the <code><a
href="mod_mime.html#sethandler">SetHandler</a></code>
directive. For example, to enable status requests, but allow
them only from browsers at foo.com, you might use:</p>
<pre>
&lt;Location /status&gt;
SetHandler server-status
Order Deny,Allow
Deny from all
Allow from .foo.com
&lt;/Location&gt;
</pre>
<p><strong>Apache 1.3 and above note about / (slash)</strong>:
The slash character has special meaning depending on where in a
URL it appears. People may be used to its behavior in the
filesystem where multiple adjacent slashes are frequently
collapsed to a single slash (<em>i.e.</em>,
<code>/home///foo</code> is the same as
<code>/home/foo</code>). In URL-space this is not necessarily
true. The <code>&lt;LocationMatch&gt;</code> directive and the
regex version of <code>&lt;Location&gt;</code> require you to
explicitly specify multiple slashes if that is your intention.
For example, <code>&lt;LocationMatch ^/abc&gt;</code> would
match the request URL <code>/abc</code> but not the request URL
<code>//abc</code>. The (non-regex)
<code>&lt;Location&gt;</code> directive behaves similarly when
used for proxy requests. But when (non-regex)
<code>&lt;Location&gt;</code> is used for non-proxy requests it
will implicitly match multiple slashes with a single slash. For
example, if you specify <code>&lt;Location /abc/def&gt;</code>
and the request is to <code>/abc//def</code> then it will
match.</p>
<p><strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received</p>
<hr />
<h2><a id="locationmatch"
name="locationmatch">&lt;LocationMatch&gt;</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;LocationMatch
<em>regex</em>&gt; ... &lt;/LocationMatch&gt;<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> LocationMatch is
only available in Apache 1.3 and later.
<p>The &lt;LocationMatch&gt; directive provides for access
control by URL, in an identical manner to <a
href="#location">&lt;Location&gt;</a>. However, it takes a
regular expression as an argument instead of a simple string.
For example:</p>
<pre>
&lt;LocationMatch "/(extra|special)/data"&gt;
</pre>
<p>would match URLs that contained the substring "/extra/data"
or "/special/data".</p>
<strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received
<hr />
<h2><a id="lockfile" name="lockfile">LockFile
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LockFile
<em>file-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>LockFile
logs/accept.lock</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The LockFile directive sets the path to the lockfile used
when Apache is compiled with either USE_FCNTL_SERIALIZED_ACCEPT
or USE_FLOCK_SERIALIZED_ACCEPT. This directive should normally
be left at its default value. The main reason for changing it
is if the <code>logs</code> directory is NFS mounted, since
<strong>the lockfile must be stored on a local disk</strong>.
The PID of the main server process is automatically appended to
the filename.</p>
<p><strong>SECURITY:</strong> It is best to avoid putting this
file in a world writable directory such as
<code>/var/tmp</code> because someone could create a denial of
service attack and prevent the server from starting by creating
a lockfile with the same name as the one the server will try to
create.</p>
<hr />
<h2><a id="loglevel" name="loglevel">LogLevel
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> LogLevel
<em>level</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>LogLevel
warn</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> LogLevel is only
available in 1.3 or later.
<p>LogLevel adjusts the verbosity of the messages recorded in
the error logs (see <a href="#errorlog">ErrorLog</a>
directive). The following <em>level</em>s are available, in
order of decreasing significance:</p>
<table>
<tr>
<th align="left"><strong>Level</strong> </th>
<th align="left"><strong>Description</strong> </th>
<th align="left"><strong>Example</strong> </th>
</tr>
<tr>
<td><code>emerg</code> </td>
<td>Emergencies - system is unusable.</td>
<td>"Child cannot open lock file. Exiting"</td>
</tr>
<tr>
<td><code>alert</code> </td>
<td>Action must be taken immediately.</td>
<td>"getpwuid: couldn't determine user name from uid"</td>
</tr>
<tr>
<td><code>crit</code> </td>
<td>Critical Conditions.</td>
<td>"socket: Failed to get a socket, exiting child"</td>
</tr>
<tr>
<td><code>error</code> </td>
<td>Error conditions.</td>
<td>"Premature end of script headers"</td>
</tr>
<tr>
<td><code>warn</code> </td>
<td>Warning conditions.</td>
<td>"child process 1234 did not exit, sending another
SIGHUP"</td>
</tr>
<tr>
<td><code>notice</code> </td>
<td>Normal but significant condition.</td>
<td>"httpd: caught SIGBUS, attempting to dump core in
..."</td>
</tr>
<tr>
<td><code>info</code> </td>
<td>Informational.</td>
<td>"Server seems busy, (you may need to increase
StartServers, or Min/MaxSpareServers)..."</td>
</tr>
<tr>
<td><code>debug</code> </td>
<td>Debug-level messages</td>
<td>"Opening config file ..."</td>
</tr>
</table>
<p>When a particular level is specified, messages from all
other levels of higher significance will be reported as well.
<em>E.g.</em>, when <code>LogLevel info</code> is specified,
then messages with log levels of <code>notice</code> and
<code>warn</code> will also be posted.</p>
<p>Using a level of at least <code>crit</code> is
recommended.</p>
<p>For example:</p>
<pre>LogLevel notice</pre>
<p><strong>NOTE:</strong> When logging to a regular file messages
of the level <code>notice</code> cannot be suppressed and thus are
always logged. However, this doesn't apply when logging is done
using <code>syslog</code>.</p>
<hr />
<h2><a id="maxclients" name="maxclients">MaxClients
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> MaxClients
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>MaxClients
256</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The MaxClients directive sets the limit on the number of
simultaneous requests that can be supported; not more than this
number of child server processes will be created. To configure
more than 256 clients, you must edit the HARD_SERVER_LIMIT
entry in httpd.h and recompile.</p>
<p>Any connection attempts over the MaxClients limit will
normally be queued, up to a number based on the <a
href="#listenbacklog">ListenBacklog</a> directive. Once a child
process is freed at the end of a different request, the
connection will then be serviced.</p>
<hr />
<h2><a id="maxkeepaliverequests"
name="maxkeepaliverequests">MaxKeepAliveRequests
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> MaxKeepAliveRequests
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>MaxKeepAliveRequests 100</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Only available
in Apache 1.2 and later.
<p>The MaxKeepAliveRequests directive limits the number of
requests allowed per connection when <a
href="#keepalive">KeepAlive</a> is on. If it is set to
"<code>0</code>", unlimited requests will be allowed. We
recommend that this setting be kept to a high value for maximum
server performance. In Apache 1.1, this is controlled through
an option to the KeepAlive directive.</p>
<p>For example</p>
<pre>MaxKeepAliveRequests 500</pre>
<hr />
<h2><a id="maxrequestsperchild"
name="maxrequestsperchild">MaxRequestsPerChild
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> MaxRequestsPerChild
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>MaxRequestsPerChild 0</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The MaxRequestsPerChild directive sets the limit on the
number of requests that an individual child server process will
handle. After MaxRequestsPerChild requests, the child process
will die. If MaxRequestsPerChild is 0, then the process will
never expire.</p>
<p>Setting MaxRequestsPerChild to a non-zero limit has two
beneficial effects:</p>
<ul>
<li>it limits the amount of memory that process can consume
by (accidental) memory leakage;</li>
<li>by giving processes a finite lifetime, it helps reduce
the number of processes when the server load reduces.</li>
</ul>
<p>However, on Win32, It is recommended that this be set to 0.
If it is set to a non-zero value, when the request count is
reached, the child process exits, and is respawned, at which
time it re-reads the configuration files. This can lead to
unexpected behavior if you have modified a configuration file,
but are not expecting the changes to be applied yet. See also
<a href="#threadsperchild">ThreadsPerChild</a>.</p>
<p><strong>NOTE:</strong> For <em>KeepAlive</em> requests, only
the first request is counted towards this limit. In effect, it
changes the behavior to limit the number of
<em>connections</em> per child.</p>
<hr />
<h2><a id="maxspareservers"
name="maxspareservers">MaxSpareServers directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> MaxSpareServers
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>MaxSpareServers
10</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The MaxSpareServers directive sets the desired maximum
number of <em>idle</em> child server processes. An idle process
is one which is not handling a request. If there are more than
MaxSpareServers idle, then the parent process will kill off the
excess processes.</p>
<p>Tuning of this parameter should only be necessary on very
busy sites. Setting this parameter to a large number is almost
always a bad idea.</p>
<p>Note that this is the maximum number of <em>spare</em> servers,
not the maximum total number of client requests that can be handled
at one time. If you wish to limit that number, see the <a
href="#maxclients">MaxClients</a> directive.</p>
<p>This directive has no effect when used with the Apache Web
server on a Microsoft Windows platform.</p>
<p>See also <a href="#minspareservers">MinSpareServers</a>,
<a href="#startservers">StartServers</a>, and <a
href="#maxclients">MaxClients</a>.</p>
<hr />
<h2><a id="minspareservers"
name="minspareservers">MinSpareServers directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> MinSpareServers
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>MinSpareServers
5</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The MinSpareServers directive sets the desired minimum
number of <em>idle</em> child server processes. An idle process
is one which is not handling a request. If there are fewer than
MinSpareServers idle, then the parent process creates new
children at a maximum rate of 1 per second.</p>
<p>Tuning of this parameter should only be necessary on very
busy sites. Setting this parameter to a large number is almost
always a bad idea.</p>
<p>Note that setting this directive to some value <i>m</i> ensures
that you will always have at least <i>n + m</i> <code>httpd</code>
processes running when you have <i>n</i> active client requests.</p>
<p>This directive has no effect on Microsoft Windows.</p>
<p>See also <a href="#maxspareservers">MaxSpareServers</a>,
<a href="#startservers">StartServers</a>, and <a
href="#maxclients">MaxClients</a>.</p>
<hr />
<h2><a id="namevirtualhost"
name="namevirtualhost">NameVirtualHost directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> NameVirtualHost
<em>addr</em>[:<em>port</em>]<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> NameVirtualHost
is only available in Apache 1.3 and later
<p>The NameVirtualHost directive is a required directive if you
want to configure <a href="../vhosts/">name-based virtual
hosts</a>.</p>
<p>Although <em>addr</em> can be hostname it is recommended
that you always use an IP address or wildcard,
<em>e.g.</em></p>
<blockquote>
<code>NameVirtualHost 111.22.33.44</code>
</blockquote>
With the NameVirtualHost directive you specify the IP address
on which the server will receive requests for the name-based
virtual hosts. This will usually be the address to which your
name-based virtual host names resolve. In cases where a
firewall or other proxy receives the requests and forwards them
on a different IP address to the server, you must specify the
IP address of the physical interface on the machine which will
be servicing the requests. If you have multiple name-based
hosts on multiple addresses, repeat the directive for each
address.
<p>Note: the "main server" and any _default_ servers will
<strong>never</strong> be served for a request to a
NameVirtualHost IP Address (unless for some reason you specify
NameVirtualHost but then don't define any VirtualHosts for that
address).</p>
<p>Optionally you can specify a port number on which the
name-based virtual hosts should be used, <em>e.g.</em></p>
<blockquote>
<code>NameVirtualHost 111.22.33.44:8080</code>
</blockquote>
In Apache 1.3.13 and greater you can specify a <code>*</code>
for the <em>addr</em>. This creates a wildcard NameVirtualHost
which will match connections to any address that isn't
configured with a more specific NameVirtualHost directive or <a
href="#virtualhost">&lt;VirtualHost&gt;</a> section. This is
useful if you want only name-based virtual hosts and you don't
want to hard-code the server's IP address into the
configuration file.
<p><strong>See also:</strong> <a href="../vhosts/">Apache
Virtual Host documentation</a></p>
<hr />
<h2><a id="options" name="options">Options directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Options
[+|-]<em>option</em> [[+|-]<em>option</em>] ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> Options<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The Options directive controls which server features are
available in a particular directory.</p>
<p><em>option</em> can be set to <code>None</code>, in which
case none of the extra features are enabled, or one or more of
the following:</p>
<dl>
<dt>All</dt>
<dd>All options except for MultiViews. This is the default
setting.</dd>
<dt>ExecCGI</dt>
<dd>
Execution of CGI scripts is permitted.</dd>
<dt>FollowSymLinks</dt>
<dd>
The server will follow symbolic links in this
directory.<br />
<strong>Note</strong>: even though the server follows the
symlink it does <em>not</em> change the pathname used to
match against <code>&lt;Directory&gt;</code> sections.<br />
<strong>Note</strong>: this option gets ignored if set
inside a &lt;Location&gt; section.</dd>
<dt>Includes</dt>
<dd>
Server-side includes are permitted.</dd>
<dt>IncludesNOEXEC</dt>
<dd>
Server-side includes are permitted, but the #exec command and
#exec CGI are disabled. It is still possible to #include
virtual CGI scripts from ScriptAliase'd directories.</dd>
<dt>Indexes</dt>
<dd>
If a URL which maps to a directory is requested, and the
there is no DirectoryIndex (<em>e.g.</em>, index.html) in
that directory, then the server will return a formatted
listing of the directory.</dd>
<dt>MultiViews</dt>
<dd>
<a href="../content-negotiation.html">Content negotiated</a>
MultiViews are allowed.</dd>
<dt>SymLinksIfOwnerMatch</dt>
<dd>
The server will only follow symbolic links for which the
target file or directory is owned by the same user id as the
link.<br />
<strong>Note</strong>: this option gets ignored if set
inside a &lt;Location&gt; section.</dd>
</dl>
Normally, if multiple <code>Options</code> could apply to a
directory, then the most specific one is taken complete; the
options are not merged. However if <em>all</em> the options on
the <code>Options</code> directive are preceded by a + or -
symbol, the options are merged. Any options preceded by a + are
added to the options currently in force, and any options
preceded by a - are removed from the options currently in
force.
<p>For example, without any + and - symbols:</p>
<blockquote>
<code>&lt;Directory /web/docs&gt;<br />
Options Indexes FollowSymLinks<br />
&lt;/Directory&gt;<br />
&lt;Directory /web/docs/spec&gt;<br />
Options Includes<br />
&lt;/Directory&gt;</code>
</blockquote>
then only <code>Includes</code> will be set for the
/web/docs/spec directory. However if the second
<code>Options</code> directive uses the + and - symbols:
<blockquote>
<code>&lt;Directory /web/docs&gt;<br />
Options Indexes FollowSymLinks<br />
&lt;/Directory&gt;<br />
&lt;Directory /web/docs/spec&gt;<br />
Options +Includes -Indexes<br />
&lt;/Directory&gt;</code>
</blockquote>
then the options <code>FollowSymLinks</code> and
<code>Includes</code> are set for the /web/docs/spec directory.
<p><strong>Note:</strong> Using <code>-IncludesNOEXEC</code> or
<code>-Includes</code> disables server-side includes completely
regardless of the previous setting.</p>
<p>The default in the absence of any other settings is
<code>All</code>.</p>
<hr />
<h2><a id="pidfile" name="pidfile">PidFile directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> PidFile
<em>file-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>PidFile
logs/httpd.pid</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The PidFile directive sets the file to which the server
records the process id of the daemon. If the filename does not
begin with a slash (/) then it is assumed to be relative to the
<a href="#serverroot">ServerRoot</a>. The PidFile is only used
in <a href="#servertype">standalone</a> mode.</p>
<p>It is often useful to be able to send the server a signal,
so that it closes and then reopens its <a
href="#errorlog">ErrorLog</a> and TransferLog, and re-reads its
configuration files. This is done by sending a SIGHUP (kill -1)
signal to the process id listed in the PidFile.</p>
<p>The PidFile is subject to the same warnings about log file
placement and <a
href="../misc/security_tips.html#serverroot">security</a>.</p>
<hr />
<h2><a id="port" name="port">Port directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Port
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>Port
80</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p><em>Number</em> is a number from 0 to 65535; some port
numbers (especially below 1024) are reserved for particular
protocols. See <code>/etc/services</code> for a list of some
defined ports; the standard port for the http protocol is
80.</p>
<p>The Port directive has two behaviors, the first of which is
necessary for NCSA backwards compatibility (and which is
confusing in the context of Apache).</p>
<ul>
<li>In the absence of any <a href="#listen">Listen</a> or <a
href="#bindaddress">BindAddress</a> directives specifying a
port number, a Port directive given in the "main server"
(<em>i.e.</em>, outside any <a
href="#virtualhost">&lt;VirtualHost&gt;</a> section) sets the
network port on which the server listens. If there are any
Listen or BindAddress directives specifying
<code>:number</code> then Port has no effect on what address
the server listens at.</li>
<li>The Port directive sets the <code>SERVER_PORT</code>
environment variable (for <a href="mod_cgi.html">CGI</a> and
<a href="mod_include.html">SSI</a>), and is used when the
server must generate a URL that refers to itself (for example
when creating an external redirect to itself). This behavior
is modified by <a
href="#usecanonicalname">UseCanonicalName</a>.</li>
</ul>
The primary behavior of Port should be considered to be
similar to that of the <a href="#servername">ServerName</a>
directive. The ServerName and Port together specify what you
consider to be the <em>canonical</em> address of the server.
(See also <a href="#usecanonicalname">UseCanonicalName</a>.)
<p>Port 80 is one of Unix's special ports. All ports numbered
below 1024 are reserved for system use, <em>i.e.</em>, regular
(non-root) users cannot make use of them; instead they can only
use higher port numbers. To use port 80, you must start the
server from the root account. After binding to the port and
before accepting requests, Apache will change to a low
privileged user as set by the <a href="#user">User
directive</a>.</p>
<p>If you cannot use port 80, choose any other unused port.
Non-root users will have to choose a port number higher than
1023, such as 8000.</p>
<p>SECURITY: if you do start the server as root, be sure not to
set <a href="#user">User</a> to root. If you run the server as
root whilst handling connections, your site may be open to a
major security attack.</p>
<hr />
<h2><a id="protocolreqcheck" name="protocolreqcheck">ProtocolReqCheck
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ProtocolReqCheck
on|off<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ProtocolReqCheck
on</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config
<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a>
ProtocolReqCheck is only available in Apache 1.3.27 and later.
<p>This directive enables strict checking of the Protocol field
in the Request line. Versions of Apache prior to 1.3.26 would
silently accept bogus Protocols (such as <code>HTTP-1.1</code>)
and assume <code>HTTP/1.0</code>. Instead, now the Protocol field
must be valid. If the pre-1.3.26 behavior is desired or required,
it can be enabled via setting <code>ProtocolReqCheck off</code>.
</p>
<hr />
<h2><a id="require" name="require">Require directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Require
<em>entity-name</em> [<em>entity-name</em>] ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory,
.htaccess<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> AuthConfig<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>This directive selects which authenticated users can access
a resource. The allowed syntaxes are:</p>
<ul>
<li>
Require user <em>userid</em> [<em>userid</em>] ...
<p>Only the named users can access the resource.</p>
</li>
<li>
Require group <em>group-name</em> [<em>group-name</em>] ...
<p>Only users in the named groups can access the
resource.</p>
</li>
<li>
Require valid-user
<p>All valid users can access the resource.</p>
</li>
<li>file-owner
<p>Only the user, whose name matches the system's name for
the file owner, can access the resource.<br>
[Available after Apache 1.3.20]</p>
</li>
<li>file-group
<p>Only the members of the group, whose name matches the
system's name of the file owner group, can access the
resource.<br>[Available after Apache 1.3.20]</p>
</li>
</ul>
<p>Require must be accompanied by <a
href="#authname">AuthName</a> and <a
href="#authtype">AuthType</a> directives, and directives such
as <a href="mod_auth.html#authuserfile">AuthUserFile</a> and <a
href="mod_auth.html#authgroupfile">AuthGroupFile</a> (to define
users and groups) in order to work correctly. Example:</p>
<blockquote>
<code>AuthType Basic<br />
AuthName "Restricted Directory"<br />
AuthUserFile /web/users<br />
AuthGroupFile /web/groups<br />
Require group admin<br />
</code>
</blockquote>
Access controls which are applied in this way are effective for
<strong>all</strong> methods. <strong>This is what is normally
desired.</strong> If you wish to apply access controls only to
specific methods, while leaving other methods unprotected, then
place the <code>Require</code> statement into a <a
href="#limit">&lt;Limit&gt;</a> section
<p>See also <a href="#satisfy">Satisfy</a> and <a
href="mod_access.html">mod_access</a>.</p>
<hr />
<h2><a id="resourceconfig" name="resourceconfig">ResourceConfig
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ResourceConfig
<em>file-path</em>|<em>directory-path</em>|<em>wildcard-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ResourceConfig
conf/srm.conf</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core <br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> The ability to
specify a directory, rather than a file name, is only available in
Apache 1.3.13 and later.
<p>The server will read this file for more directives after
reading the httpd.conf file. <em>File-path</em> is relative to
the <a href="#serverroot">ServerRoot</a>. This feature can be
disabled using:</p>
<blockquote>
<code>ResourceConfig /dev/null</code>
</blockquote>
Or, on Win32 servers,
<blockquote>
<code>ResourceConfig nul</code>
</blockquote>
<p>Historically, this file contained most directives except for
server configuration directives and <a
href="#directory">&lt;Directory&gt;</a> sections; in fact it
can now contain any server directive allowed in the <em>server
config</em> context. However, since Apache version 1.3.4, the
default <code>srm.conf</code> file which ships with Apache contains
only comments, and all directives are placed in the main server
configuration file, <code>httpd.conf</code>.</p>
<p>If <code>ResourceConfig</code> points to a directory, rather than
a file, Apache will read all files in that directory, and any
subdirectory, and parse those as configuration files.
</p>
<p>Alternatively you can use a wildcard to limit the scope; i.e
to only *.conf files.
</p>
<p>Note that by default <em>any</em> file in the specified
directory will be loaded as a configuration file.
</p>
<p>So make sure that you don't have stray files in
this directory by mistake, such as temporary files created by your
editor, for example.</p>
<p>See also <a href="#accessconfig">AccessConfig</a>.</p>
<hr />
<h2><a id="rlimit" name="rlimit">RLimitCPU</a> <a
id="rlimitcpu" name="rlimitcpu">directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> RLimitCPU
<em>number</em>|max [<em>number</em>|max] <br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <em>Unset; uses
operating system defaults</em> <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> RLimitCPU is
only available in Apache 1.2 and later
<p>Takes 1 or 2 parameters. The first parameter sets the soft
resource limit for all processes and the second parameter sets
the maximum resource limit. Either parameter can be a number,
or <code>max</code> to indicate to the server that the limit
should be set to the maximum allowed by the operating system
configuration. Raising the maximum resource limit requires that
the server is running as root, or in the initial startup
phase.</p>
<p>This applies to processes forked off from Apache children
servicing requests, not the Apache children themselves. This
includes CGI scripts and SSI exec commands, but not any
processes forked off from the Apache parent such as piped
logs.</p>
<p>CPU resource limits are expressed in seconds per
process.</p>
<p>See also <a href="#rlimitmem">RLimitMEM</a> or <a
href="#rlimitnproc">RLimitNPROC</a>.</p>
<hr />
<h2><a id="rlimitmem" name="rlimitmem">RLimitMEM
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> RLimitMEM
<em>number</em>|max [<em>number</em>|max]<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <em>Unset; uses
operating system defaults</em> <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> RLimitMEM is
only available in Apache 1.2 and later
<p>Takes 1 or 2 parameters. The first parameter sets the soft
resource limit for all processes and the second parameter sets
the maximum resource limit. Either parameter can be a number,
or <code>max</code> to indicate to the server that the limit
should be set to the maximum allowed by the operating system
configuration. Raising the maximum resource limit requires that
the server is running as root, or in the initial startup
phase.</p>
<p>This applies to processes forked off from Apache children
servicing requests, not the Apache children themselves. This
includes CGI scripts and SSI exec commands, but not any
processes forked off from the Apache parent such as piped
logs.</p>
<p>Memory resource limits are expressed in bytes per
process.</p>
<p>See also <a href="#rlimitcpu">RLimitCPU</a> or <a
href="#rlimitnproc">RLimitNPROC</a>.</p>
<hr />
<h2><a id="rlimitnproc" name="rlimitnproc">RLimitNPROC
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> RLimitNPROC
<em>number</em>|max [<em>number</em>|max]<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <em>Unset; uses
operating system defaults</em> <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> RLimitNPROC is
only available in Apache 1.2 and later
<p>Takes 1 or 2 parameters. The first parameter sets the soft
resource limit for all processes and the second parameter sets
the maximum resource limit. Either parameter can be a number,
or <code>max</code> to indicate to the server that the limit
should be set to the maximum allowed by the operating system
configuration. Raising the maximum resource limit requires that
the server is running as root, or in the initial startup
phase.</p>
<p>This applies to processes forked off from Apache children
servicing requests, not the Apache children themselves. This
includes CGI scripts and SSI exec commands, but not any
processes forked off from the Apache parent such as piped
logs.</p>
<p>Process limits control the number of processes per user.</p>
<p>Note: If CGI processes are <strong>not</strong> running
under userids other than the web server userid, this directive
will limit the number of processes that the server itself can
create. Evidence of this situation will be indicated by
<strong><em>cannot fork</em></strong> messages in the
error_log.</p>
<p>See also <a href="#rlimitmem">RLimitMEM</a> or <a
href="#rlimitcpu">RLimitCPU</a>.</p>
<hr />
<h2><a id="satisfy" name="satisfy">Satisfy directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Satisfy any|all<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> Satisfy all<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory,
.htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Satisfy is only
available in Apache 1.2 and later
<p>Access policy if both <code>Allow</code> and
<code>Require</code> used. The parameter can be either
<em>'all'</em> or <em>'any'</em>. This directive is only useful
if access to a particular area is being restricted by both
username/password <em>and</em> client host address. In this
case the default behavior ("all") is to require that the client
passes the address access restriction <em>and</em> enters a
valid username and password. With the "any" option the client
will be granted access if they either pass the host restriction
or enter a valid username and password. This can be used to
password restrict an area, but to let clients from particular
addresses in without prompting for a password.</p>
<p>See also <a href="#require">Require</a> and <a
href="mod_access.html#allow">Allow</a>.</p>
<hr />
<h2><a id="scoreboardfile" name="scoreboardfile">ScoreBoardFile
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ScoreBoardFile
<em>file-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ScoreBoardFile
logs/apache_status</code> <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The ScoreBoardFile directive is required on some
architectures to place a file that the server will use to
communicate between its children and the parent. The easiest
way to find out if your architecture requires a scoreboard file
is to run Apache and see if it creates the file named by the
directive. If your architecture requires it then you must
ensure that this file is not used at the same time by more than
one invocation of Apache.</p>
<p>If you have to use a ScoreBoardFile then you may see
improved speed by placing it on a RAM disk. But be careful that
you heed the same warnings about log file placement and <a
href="../misc/security_tips.html">security</a>.</p>
<p>Apache 1.2 and above:</p>
<p>Linux 1.x users might be able to add <code>-DHAVE_SHMGET
-DUSE_SHMGET_SCOREBOARD</code> to the <code>EXTRA_CFLAGS</code>
in your <code>Configuration</code>. This might work with some
1.x installations, but won't work with all of them. (Prior to
1.3b4, <code>HAVE_SHMGET</code> would have sufficed.)</p>
<p>SVR4 users should consider adding <code>-DHAVE_SHMGET
-DUSE_SHMGET_SCOREBOARD</code> to the <code>EXTRA_CFLAGS</code>
in your <code>Configuration</code>. This is believed to work,
but we were unable to test it in time for 1.2 release. (Prior
to 1.3b4, <code>HAVE_SHMGET</code> would have sufficed.)</p>
<p><strong>See Also</strong>: <a
href="../stopping.html">Stopping and Restarting Apache</a></p>
<hr />
<h2><a id="scriptinterpretersource"
name="scriptinterpretersource">ScriptInterpreterSource
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ScriptInterpreterSource
registry|script<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>ScriptInterpreterSource script</code> <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> directory,
.htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core (Windows only)
<p>This directive is used to control how Apache 1.3.5 and later
finds the interpreter used to run CGI scripts. The default
technique is to use the interpreter pointed to by the #! line
in the script. Setting ScriptInterpreterSource registry will
cause the Windows Registry to be searched using the script file
extension (e.g., .pl) as a search key.</p>
<hr />
<h2><a id="sendbuffersize" name="sendbuffersize">SendBufferSize
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> SendBufferSize
<em>bytes</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The server will set the TCP buffer size to the number of
bytes specified. Very useful to increase past standard OS
defaults on high speed high latency (<em>i.e.</em>, 100ms or
so, such as transcontinental fast pipes)</p>
<hr />
<h2><a id="serveradmin" name="serveradmin">ServerAdmin
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerAdmin
<em>email-address</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The ServerAdmin sets the e-mail address that the server
includes in any error messages it returns to the client.</p>
<p>It may be worth setting up a dedicated address for this,
<em>e.g.</em></p>
<blockquote>
<code>ServerAdmin www-admin@foo.bar.com</code>
</blockquote>
as users do not always mention that they are talking about the
server!
<hr />
<h2><a id="serveralias" name="serveralias">ServerAlias
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerAlias
<em>hostname</em> [<em>hostname</em>] ...<br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> virtual host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ServerAlias is
only available in Apache 1.1 and later.
<p>The ServerAlias directive sets the alternate names for a
host, for use with <a
href="../vhosts/name-based.html">name-based virtual
hosts</a>.</p>
<p>Example:</p>
<pre>
&lt;VirtualHost *&gt;
ServerName server.domain.com
ServerAlias server server2.domain.com server2
...
&lt;/VirtualHost&gt;
</pre>
<p><strong>See also:</strong> <a href="../vhosts/">Apache
Virtual Host documentation</a></p>
<hr />
<h2><a id="servername" name="servername">ServerName
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerName
<em>fully-qualified-domain-name</em> <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The ServerName directive sets the hostname of the server;
this is used when creating redirection URLs. If it is not
specified, then the server attempts to deduce it from its own
IP address; however this may not work reliably, or may not
return the preferred hostname. For example:</p>
<blockquote>
<code>ServerName www.example.com</code>
</blockquote>
would be used if the canonical (main) name of the actual
machine were <code>simple.example.com</code>.
<p>If you are using <a
href="../vhosts/name-based.html">name-based virtual hosts</a>,
the <code>ServerName</code> inside a <a
href="#virtualhost"><code>&lt;VirtualHost&gt;</code></a>
section specifies what hostname must appear in the request's
<code>Host:</code> header to match this virtual host.</p>
<p><strong>See Also</strong>:<br />
<a href="../dns-caveats.html">DNS Issues</a><br />
<a href="../vhosts/">Apache virtual host
documentation</a><br />
<a href="#usecanonicalname">UseCanonicalName</a><br />
<a href="#namevirtualhost">NameVirtualHost</a><br />
<a href="#serveralias">ServerAlias</a><br />
</p>
<hr />
<h2><a id="serverpath" name="serverpath">ServerPath
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerPath
<em>directory-path</em><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> virtual host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ServerPath is
only available in Apache 1.1 and later.
<p>The ServerPath directive sets the legacy URL pathname for a
host, for use with <a href="../vhosts/">name-based virtual
hosts</a>.</p>
<p><strong>See also:</strong> <a href="../vhosts/">Apache
Virtual Host documentation</a></p>
<hr />
<h2><a id="serverroot" name="serverroot">ServerRoot
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerRoot
<em>directory-path</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ServerRoot
/usr/local/apache</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The ServerRoot directive sets the directory in which the
server lives. Typically it will contain the subdirectories
<code>conf/</code> and <code>logs/</code>. Relative paths for
other configuration files are taken as relative to this
directory.</p>
<p>See also <a href="../invoking.html">the <code>-d</code>
option to httpd</a>.</p>
<p>See also <a href="../misc/security_tips.html#serverroot">the
security tips</a> for information on how to properly set
permissions on the ServerRoot.</p>
<hr />
<h2><a id="serversignature"
name="serversignature">ServerSignature directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerSignature
On|Off|EMail<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ServerSignature
Off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory, .htaccess<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ServerSignature
is only available in Apache 1.3 and later.
<p>The ServerSignature directive allows the configuration of a
trailing footer line under server-generated documents (error
messages, mod_proxy ftp directory listings, mod_info output,
...). The reason why you would want to enable such a footer
line is that in a chain of proxies, the user often has no
possibility to tell which of the chained servers actually
produced a returned error message.<br />
The <samp>Off</samp> setting, which is the default, suppresses
the error line (and is therefore compatible with the behavior
of Apache-1.2 and below). The <samp>On</samp> setting simply
adds a line with the server version number and <a
href="#servername">ServerName</a> of the serving virtual host,
and the <samp>EMail</samp> setting additionally creates a
"mailto:" reference to the <a
href="#serveradmin">ServerAdmin</a> of the referenced
document.</p>
<hr />
<h2><a id="servertokens" name="servertokens">ServerTokens
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerTokens
Minimal|ProductOnly|OS|Full<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ServerTokens
Full</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config <br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> ServerTokens is
only available in Apache 1.3 and later; the
<code>ProductOnly</code> keyword is only available in versions
later than 1.3.12
<p>This directive controls whether <samp>Server</samp> response
header field which is sent back to clients includes a
description of the generic OS-type of the server as well as
information about compiled-in modules.</p>
<dl>
<dt><code>ServerTokens Prod[uctOnly]</code></dt>
<dd>Server sends (<em>e.g.</em>): <samp>Server:
Apache</samp></dd>
<dt><code>ServerTokens Min[imal]</code></dt>
<dd>Server sends (<em>e.g.</em>): <samp>Server:
Apache/1.3.0</samp></dd>
<dt><code>ServerTokens OS</code></dt>
<dd>Server sends (<em>e.g.</em>): <samp>Server: Apache/1.3.0
(Unix)</samp></dd>
<dt><code>ServerTokens Full</code> (or not specified)</dt>
<dd>Server sends (<em>e.g.</em>): <samp>Server: Apache/1.3.0
(Unix) PHP/3.0 MyMod/1.2</samp></dd>
</dl>
<p>This setting applies to the entire server, and cannot be
enabled or disabled on a virtualhost-by-virtualhost basis.</p>
<hr />
<h2><a id="servertype" name="servertype">ServerType
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ServerType
<em>type</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ServerType
standalone</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The ServerType directive sets how the server is executed by
the system. <em>Type</em> is one of</p>
<dl>
<dt>inetd</dt>
<dd>The server will be run from the system process inetd; the
command to start the server is added to
<code>/etc/inetd.conf</code></dd>
<dt>standalone</dt>
<dd>The server will run as a daemon process; the command to
start the server is added to the system startup scripts.
(<code>/etc/rc.local</code> or
<code>/etc/rc3.d/...</code>.)</dd>
</dl>
Inetd is the lesser used of the two options. For each http
connection received, a new copy of the server is started from
scratch; after the connection is complete, this program exits.
There is a high price to pay per connection, but for security
reasons, some admins prefer this option. <font
color="red">Inetd mode is no longer recommended and does not
always work properly. Avoid it if at all possible.</font>
<p>Standalone is the most common setting for ServerType since
it is far more efficient. The server is started once, and
services all subsequent connections. If you intend running
Apache to serve a busy site, standalone will probably be your
only option.</p>
<hr />
<h2><a id="shmemuidisuser" name="shmemuidisuser">ShmemUIDisUser
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ShmemUIDisUser
<em>on|off</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ShmemUIDisUser
off</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a>
ShmemUIDisUser directive is only available in Apache 1.3.27 and later.
<p>The ShmemUIDisUser directive controls whether Apache will change
the <code>uid</code> and <code>gid</code> ownership of System V shared memory
based scoreboards to the server settings of <a href="#user">User</a> and
<a href="#group">Group</a>. Releases of Apache up to 1.3.26 would do
this by default. Since the child processes are already attached to the
shared memory segment, this is not required for normal usage of Apache and
so to prevent possible abuse, Apache will no longer do that. The old
behavior may be required for special cases, however, which can be implemented
by setting this directive to <code>on</code>.</p>
<p>This directive has no effect on non-System V based scoreboards, such as
<code>mmap</code>.
</p>
<hr />
<h2><a id="startservers" name="startservers">StartServers
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> StartServers
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>StartServers
5</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The StartServers directive sets the number of child server
processes created on startup. As the number of processes is
dynamically controlled depending on the load, there is usually
little reason to adjust this parameter.</p>
<p>When running under Microsoft Windows, this directive has no
effect. There is always one child which handles all requests.
Within the child requests are handled by separate threads. The
<a href="#threadsperchild">ThreadsPerChild</a> directive
controls the maximum number of child threads handling requests,
which will have a similar effect to the setting of
<samp>StartServers</samp> on Unix.</p>
<p>See also <a href="#minspareservers">MinSpareServers</a> and
<a href="#maxspareservers">MaxSpareServers</a>.</p>
<hr />
<h2><a id="threadsperchild"
name="threadsperchild">ThreadsPerChild</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ThreadsPerChild
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ThreadsPerChild
50</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core (Windows,
NetWare)<br />
<strong>Compatibility:</strong> Available only with Apache 1.3
and later with Windows
<p>This directive tells the server how many threads it should
use. This is the maximum number of connections the server can
handle at once; be sure and set this number high enough for
your site if you get a lot of hits.</p>
<p>This directive has no effect on Unix systems. Unix users
should look at <a href="#startservers">StartServers</a> and <a
href="#maxrequestsperchild">MaxRequestsPerChild</a>.</p>
<hr />
<h2><a id="threadstacksize"
name="threadstacksize">ThreadStackSize</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> ThreadStackSize
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>ThreadStackSize
65536</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core (NetWare)<br />
<strong>Compatibility:</strong> Available only with Apache 1.3
and later with NetWare
<p>This directive tells the server what stack size to use for
each of the running threads. If you ever get a stack overflow
you will need to bump this number to a higher setting.</p>
<p>This directive has no effect on other systems.</p>
<hr />
<h2><a id="timeout" name="timeout">TimeOut directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> TimeOut
<em>number</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>TimeOut
300</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The TimeOut directive currently defines the amount of time
Apache will wait for three things:</p>
<ol>
<li>The total amount of time it takes to receive a GET
request.</li>
<li>The amount of time between receipt of TCP packets on a
POST or PUT request.</li>
<li>The amount of time between ACKs on transmissions of TCP
packets in responses.</li>
</ol>
We plan on making these separately configurable at some point
down the road. The timer used to default to 1200 before 1.2,
but has been lowered to 300 which is still far more than
necessary in most situations. It is not set any lower by
default because there may still be odd places in the code where
the timer is not reset when a packet is sent.
<hr />
<h2><a id="traceenable"
name="traceenable">TraceEnable</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> TraceEnable
<em>[on|off|extended]</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>TraceEnable
on</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core (Windows,
NetWare)<br />
<strong>Compatibility:</strong> Available only in Apache 1.3.34,
2.0.55 and later
<p>This directive overrides the behavior of TRACE for both
the core server and mod_proxy. The default <code>TraceEnable
on</code> permits TRACE requests per RFC 2616, which disallows
any request body to accompany the request. <code>TraceEnable
off</code> causes the core server and mod_proxy to return
a 405 FORBIDDEN error to the client.</p>
<p>Finally, for testing and diagnostic purposes only, request
bodies may be allowed using the non-compliant <code>TraceEnable
extended</code> directive. The core (as an origin server) will
restrict the request body to 64k (plus 8k for chunk headers if
Transfer-Encoding: chunked is used). The core will reflect the
full headers and all chunk headers with the request body. As a
proxy server, the request body is not restricted to 64k. At this
time the Apache 1.3 mod_proxy does not permit chunked request
bodies for any request, including the extended TRACE request.</p>
<hr />
<h2><a id="usecanonicalname"
name="usecanonicalname">UseCanonicalName directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> UseCanonicalName
on|off|dns<br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>UseCanonicalName
on</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host, directory<br />
<a href="directive-dict.html#Override"
rel="Help"><strong>Override:</strong></a> Options<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> UseCanonicalName
is only available in Apache 1.3 and later
<p>In many situations Apache has to construct a
<em>self-referential</em> URL. That is, a URL which refers back
to the same server. With <code>UseCanonicalName on</code> (and
in all versions prior to 1.3) Apache will use the <a
href="#servername">ServerName</a> and <a href="#port">Port</a>
directives to construct the canonical name for the server. This
name is used in all self-referential URLs, and for the values
of <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in
CGIs.</p>
<p>For example, if <a href="#servername">ServerName</a> is set to
<code>www.example.com</code> and <a href="#port">Port</a> is set to
<code>9090</code>, then the <em>canonical name</em> of the server is
<code>www.example.com:9090</code>. In the event that
<code>Port</code> has its default value of <code>80</code>, the
<code>:80</code> is omitted from the <em>canonical name</em>.</p>
<p>With <code>UseCanonicalName off</code> Apache will form
self-referential URLs using the hostname and port supplied by
the client if any are supplied (otherwise it will use the
canonical name, as defined above). These values are the same
that are used to implement <a
href="../vhosts/name-based.html">name based virtual hosts</a>,
and are available with the same clients. The CGI variables
<code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
constructed from the client supplied values as well.</p>
<p>An example where this may be useful is on an intranet server
where you have users connecting to the machine using short
names such as <code>www</code>. You'll notice that if the users
type a shortname, and a URL which is a directory, such as
<code>http://www/splat</code>, <em>without the trailing
slash</em> then Apache will redirect them to
<code>http://www.domain.com/splat/</code>. If you have
authentication enabled, this will cause the user to have to
authenticate twice (once for <code>www</code> and once again
for <code>www.domain.com</code> -- see <a
href="../misc/FAQ.html#prompted-twice">the FAQ on this subject for
more information</a>). But if <code>UseCanonicalName</code>
is set off, then Apache will redirect to
<code>http://www/splat/</code>.</p>
<p>There is a third option, <code>UseCanonicalName DNS</code>,
which is intended for use with mass IP-based virtual hosting to
support ancient clients that do not provide a
<code>Host:</code> header. With this option Apache does a
reverse DNS lookup on the server IP address that the client
connected to in order to work out self-referential URLs.</p>
<p><strong>Warning:</strong> if CGIs make assumptions about the
values of <code>SERVER_NAME</code> they may be broken by this
option. The client is essentially free to give whatever value
they want as a hostname. But if the CGI is only using
<code>SERVER_NAME</code> to construct self-referential URLs
then it should be just fine.</p>
<p><strong>See also:</strong> <a
href="#servername">ServerName</a>, <a href="#port">Port</a></p>
<hr />
<h2><a id="user" name="user">User directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> User
<em>unix-userid</em><br />
<a href="directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>User
#-1</code><br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config, virtual
host<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> core
<p>The User directive sets the userid as which the server will
answer requests. In order to use this directive, the standalone
server must be run initially as root. <em>Unix-userid</em> is
one of:</p>
<dl>
<dt>A username</dt>
<dd>Refers to the given user by name.</dd>
<dt># followed by a user number.</dt>
<dd>Refers to a user by their number.</dd>
</dl>
The user should have no privileges which result in it being
able to access files which are not intended to be visible to
the outside world, and similarly, the user should not be able
to execute code which is not meant for httpd requests. It is
recommended that you set up a new user and group specifically
for running the server. Some admins use user
<code>nobody</code>, but this is not always possible or
desirable. For example mod_proxy's cache, when enabled, must be
accessible to this user (see the <a
href="mod_proxy.html#cacheroot"><code>CacheRoot</code>
directive</a>).
<p>Notes: If you start the server as a non-root user, it will
fail to change to the lesser privileged user, and will instead
continue to run as that original user. If you do start the
server as root, then it is normal for the parent process to
remain running as root.</p>
<p>Special note: Use of this directive in &lt;VirtualHost&gt;
requires a properly configured <a href="../suexec.html">suEXEC
wrapper</a>. When used inside a &lt;VirtualHost&gt; in this
manner, only the user that CGIs are run as is affected. Non-CGI
requests are still processed with the user specified in the
main User directive.</p>
<p>SECURITY: Don't set User (or <a href="#group">Group</a>) to
<code>root</code> unless you know exactly what you are doing,
and what the dangers are.</p>
<hr />
<h2><a id="virtualhost" name="virtualhost">&lt;VirtualHost&gt;
directive</a></h2>
<a href="directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> &lt;VirtualHost
<em>addr</em>[:<em>port</em>] [<em>addr</em>[:<em>port</em>]]
...&gt; ... &lt;/VirtualHost&gt; <br />
<a href="directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core.<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Non-IP
address-based Virtual Hosting only available in Apache 1.1 and
later.<br />
<a href="directive-dict.html#Compatibility"
rel="Help"><strong>Compatibility:</strong></a> Multiple address
support only available in Apache 1.2 and later.
<p>&lt;VirtualHost&gt; and &lt;/VirtualHost&gt; are used to
enclose a group of directives which will apply only to a
particular virtual host. Any directive which is allowed in a
virtual host context may be used. When the server receives a
request for a document on a particular virtual host, it uses
the configuration directives enclosed in the
&lt;VirtualHost&gt; section. <em>Addr</em> can be</p>
<ul>
<li>The IP address of the virtual host</li>
<li>A fully qualified domain name for the IP address of the
virtual host.</li>
</ul>
Example:
<blockquote>
<code>&lt;VirtualHost 10.1.2.3&gt;<br />
ServerAdmin webmaster@host.foo.com<br />
DocumentRoot /www/docs/host.foo.com<br />
ServerName host.foo.com<br />
ErrorLog logs/host.foo.com-error_log<br />
TransferLog logs/host.foo.com-access_log<br />
&lt;/VirtualHost&gt;</code>
</blockquote>
Each VirtualHost must correspond to a different IP address,
different port number or a different host name for the server,
in the former case the server machine must be configured to
accept IP packets for multiple addresses. (If the machine does
not have multiple network interfaces, then this can be
accomplished with the <code>ifconfig alias</code> command (if
your OS supports it), or with kernel patches like <a
href="../misc/vif-info.html">VIF</a> (for SunOS(TM) 4.1.x)).
<p>You can specify more than one IP address. This is useful if
a machine responds to the same name on two different
interfaces. For example, if you have a VirtualHost that is
available to hosts on an internal (intranet) as well as
external (internet) network. Example:</p>
<blockquote>
<code>&lt;VirtualHost 192.168.1.2 204.255.176.199&gt;<br />
DocumentRoot /www/docs/host.foo.com<br />
ServerName host.foo.com<br />
ServerAlias host<br />
&lt;/VirtualHost&gt;</code>
</blockquote>
The special name <code>_default_</code> can be specified in
which case this virtual host will match any IP address that is
not explicitly listed in another virtual host. In the absence
of any _default_ virtual host the "main" server config,
consisting of all those definitions outside any VirtualHost
section, is used when no match occurs.
<p>You can specify a <code>:port</code> to change the port that
is matched. If unspecified then it defaults to the same port as
the most recent <code><a href="#port">Port</a></code> statement
of the main server. You may also specify <code>:*</code> to
match all ports on that address. (This is recommended when used
with <code>_default_</code>.)</p>
<p><strong>SECURITY</strong>: See the <a
href="../misc/security_tips.html">security tips</a> document
for details on why your security could be compromised if the
directory where logfiles are stored is writable by anyone other
than the user that starts the server.</p>
<p><strong>NOTE</strong>: The use of &lt;VirtualHost&gt; does
<strong>not</strong> affect what addresses Apache listens on.
You may need to ensure that Apache is listening on the correct
addresses using either <a href="#bindaddress">BindAddress</a>
or <a href="#listen">Listen</a>.</p>
<p><strong>See also:</strong> <a href="../vhosts/">Apache
Virtual Host documentation</a><br />
<strong>See also:</strong> <a
href="../dns-caveats.html">Warnings about DNS and
Apache</a><br />
<strong>See also:</strong> <a href="../bind.html">Setting
which addresses and ports Apache uses</a><br />
<strong>See also</strong>: <a href="../sections.html">How
Directory, Location and Files sections work</a> for an
explanation of how these different sections are combined when a
request is received</p>
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