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 <p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English">&nbsp;en&nbsp;</a> |
 <a href="../fr/vhosts/mass.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a> |
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     <p>This document describes how to efficiently serve an
     arbitrary number of virtual hosts with the Apache HTTP Server. A
     <a href="../rewrite/vhosts.html">separate document</a> discusses using
     <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to create dynamic mass virtual hosts.
     </p>

 </div>
 <div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#motivation">Motivation</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#overview">Overview</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#simple">Dynamic Virtual Hosts with
 mod_vhost_alias</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#homepages">Simplified Dynamic Virtual Hosts</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#combinations">Using Multiple Virtual
   Hosting Systems on the Same Server</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#ipbased">More Efficient IP-Based Virtual Hosting</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#rewrite">Mass virtual hosts with
 mod_rewrite</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#macro">Mass virtual hosts with mod_macro</a></li>
 </ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="motivation" id="motivation">Motivation</a></h2>

     <p>The techniques described here are of interest if your
     <code>httpd.conf</code> contains many
     <code>&lt;VirtualHost&gt;</code> sections that are
     substantially the same, for example:</p>

 <pre class="prettyprint lang-config">&lt;VirtualHost 111.22.33.44&gt;
     ServerName                 customer-1.example.com
     DocumentRoot        "/www/hosts/customer-1.example.com/docs"
     ScriptAlias  "/cgi-bin/"  "/www/hosts/customer-1.example.com/cgi-bin"
 &lt;/VirtualHost&gt;

 &lt;VirtualHost 111.22.33.44&gt;
     ServerName                 customer-2.example.com
     DocumentRoot        "/www/hosts/customer-2.example.com/docs"
     ScriptAlias  "/cgi-bin/"  "/www/hosts/customer-2.example.com/cgi-bin"
 &lt;/VirtualHost&gt;

 &lt;VirtualHost 111.22.33.44&gt;
     ServerName                 customer-N.example.com
     DocumentRoot        "/www/hosts/customer-N.example.com/docs"
     ScriptAlias  "/cgi-bin/"  "/www/hosts/customer-N.example.com/cgi-bin"
 &lt;/VirtualHost&gt;</pre>


     <p>We wish to replace these multiple
     <code>&lt;VirtualHost&gt;</code> blocks with a mechanism
     that works them out dynamically. This has a number of
     advantages:</p>

     <ol>
       <li>Your configuration file is smaller, so Apache starts
       more quickly and uses less memory. Perhaps more importantly, the
       smaller configuration is easier to maintain, and leaves less room
       for errors.</li>

       <li>Adding virtual hosts is simply a matter of creating the
       appropriate directories in the filesystem and entries in the
       DNS - you don't need to reconfigure or restart Apache.</li>
     </ol>

     <p>The main disadvantage is that you cannot have a different log file for
     each virtual host; however, if you have many virtual hosts, doing
     this can be a bad idea anyway, because of the <a href="fd-limits.html">number of file descriptors needed</a>.
     It is better to <a href="../logs.html#piped">log to a pipe or a fifo</a>,
     and arrange for the process at the other end to split up the log
     files into one per virtual host. One example of such a process can
     be found in the <a href="../programs/split-logfile.html">split-logfile</a>
     utility.</p>

 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="overview" id="overview">Overview</a></h2>

     <p>A virtual host is defined by two pieces of information: its
     IP address, and the contents of the <code>Host:</code> header
     in the HTTP request. The dynamic mass virtual hosting technique
     used here is based on automatically inserting this information into the
     pathname of the file that is used to satisfy the request. This
     can be most easily done by using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code>
     with Apache httpd. Alternatively,
     <a href="../rewrite/vhosts.html">mod_rewrite can
     be used</a>.</p>
     <p>Both of these modules are disabled by default; you must enable
     one of them when configuring and building Apache httpd if you want to
     use this technique.</p>

     <p>A couple of things need to be determined from the request in
     order to make the dynamic
     virtual host look like a normal one. The most important is the
     server name, which is used by the server to generate
     self-referential URLs etc. It is configured with the
     <code>ServerName</code> directive, and it is available to CGIs
     via the <code>SERVER_NAME</code> environment variable. The
     actual value used at run time is controlled by the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code>
     setting. With <code>UseCanonicalName Off</code>, the server name
     is taken from the contents of the <code>Host:</code> header in the
     request. With <code>UseCanonicalName DNS</code>, it is taken from a
     reverse DNS lookup of the virtual host's IP address. The former
     setting is used for name-based dynamic virtual hosting, and the
     latter is used for IP-based hosting. If httpd cannot work out
     the server name because there is no <code>Host:</code> header,
     or the DNS lookup fails, then the value configured with
     <code>ServerName</code> is used instead.</p>

     <p>The other thing to determine is the document root (configured
     with <code>DocumentRoot</code> and available to CGI scripts via the
     <code>DOCUMENT_ROOT</code> environment variable). In a normal
     configuration, this is used by the core module when
     mapping URIs to filenames, but when the server is configured to
     do dynamic virtual hosting, that job must be taken over by another
     module (either <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> or
     <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>), which has a different way of doing
     the mapping. Neither of these modules is responsible for
     setting the <code>DOCUMENT_ROOT</code> environment variable so
     if any CGIs or SSI documents make use of it, they will get a
     misleading value.</p>

 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="simple" id="simple">Dynamic Virtual Hosts with
 mod_vhost_alias</a></h2>

     <p>This extract from <code>httpd.conf</code> implements the
     virtual host arrangement outlined in the <a href="#motivation">Motivation</a> section above
     using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code>.</p>

 <pre class="prettyprint lang-config"># get the server name from the Host: header
 UseCanonicalName Off

 # this log format can be split per-virtual-host based on the first field
 # using the split-logfile utility.
 LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
 CustomLog "logs/access_log" vcommon

 # include the server name in the filenames used to satisfy requests
 VirtualDocumentRoot "/www/hosts/%0/docs"
 VirtualScriptAlias  "/www/hosts/%0/cgi-bin"</pre>


     <p>This configuration can be changed into an IP-based virtual
     hosting solution by just turning <code>UseCanonicalName
     Off</code> into <code>UseCanonicalName DNS</code>. The server
     name that is inserted into the filename is then derived from
     the IP address of the virtual host. The variable <code>%0</code>
     references the requested servername, as indicated in the
     <code>Host:</code> header.</p>

 <p>See the <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation for more usage
 examples.</p>

 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="homepages" id="homepages">Simplified Dynamic Virtual Hosts</a></h2>

     <p>This is an adjustment of the above system, tailored for an
     ISP's web hosting server. Using <code>%2</code>,
     we can select substrings of the server name to
     use in the filename so that, for example, the documents for
     <code>www.user.example.com</code> are found in
     <code>/home/user/www</code>. It uses a single <code>cgi-bin</code>
     directory instead of one per virtual host.</p>

 <pre class="prettyprint lang-config">UseCanonicalName Off

 LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
 CustomLog "logs/access_log" vcommon

 # include part of the server name in the filenames
 VirtualDocumentRoot "/home/%2/www"

 # single cgi-bin directory
 ScriptAlias  "/cgi-bin/"  "/www/std-cgi/"</pre>


     <p>There are examples of more complicated
     <code>VirtualDocumentRoot</code> settings in the
     <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation.</p>

 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="combinations" id="combinations">Using Multiple Virtual
   Hosting Systems on the Same Server</a></h2>

     <p>With more complicated setups, you can use httpd's normal
     <code>&lt;VirtualHost&gt;</code> directives to control the
     scope of the various virtual hosting configurations. For
     example, you could have one IP address for general customers' homepages,
     and another for commercial customers, with the following setup.
     This can be combined with conventional
     <code>&lt;VirtualHost&gt;</code> configuration sections, as shown
     below.</p>

 <pre class="prettyprint lang-config">UseCanonicalName Off

 LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon

 &lt;Directory "/www/commercial"&gt;
     Options FollowSymLinks
     AllowOverride All
 &lt;/Directory&gt;

 &lt;Directory "/www/homepages"&gt;
     Options FollowSymLinks
     AllowOverride None
 &lt;/Directory&gt;

 &lt;VirtualHost 111.22.33.44&gt;
     ServerName www.commercial.example.com

     CustomLog "logs/access_log.commercial" vcommon

     VirtualDocumentRoot "/www/commercial/%0/docs"
     VirtualScriptAlias  "/www/commercial/%0/cgi-bin"
 &lt;/VirtualHost&gt;

 &lt;VirtualHost 111.22.33.45&gt;
     ServerName www.homepages.example.com

     CustomLog "logs/access_log.homepages" vcommon

     VirtualDocumentRoot "/www/homepages/%0/docs"
     ScriptAlias         "/cgi-bin/" "/www/std-cgi/"
 &lt;/VirtualHost&gt;</pre>


 <div class="note">
     <h3>Note</h3>
     <p>If the first VirtualHost block does <em>not</em> include a
     <code class="directive"><a href="../mod/core.html#servername">ServerName</a></code> directive, the reverse
     DNS of the relevant IP will be used instead.
     If this is not the server name you
     wish to use, a bogus entry (eg. <code>ServerName
     none.example.com</code>) can be added to get around this
     behaviour.</p>
 </div>

 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="ipbased" id="ipbased">More Efficient IP-Based Virtual Hosting</a></h2>

     <p>The configuration changes suggested to turn <a href="#simple">the first
     example</a> into an IP-based virtual hosting setup result in
     a rather inefficient setup. A new DNS lookup is required for every
     request. To avoid this overhead, the filesystem can be arranged to
     correspond to the IP addresses, instead of to the host names, thereby
     negating the need for a DNS lookup. Logging will also have to be adjusted
     to fit this system.</p>

 <pre class="prettyprint lang-config"># get the server name from the reverse DNS of the IP address
 UseCanonicalName DNS

 # include the IP address in the logs so they may be split
 LogFormat "%A %h %l %u %t \"%r\" %s %b" vcommon
 CustomLog "logs/access_log" vcommon

 # include the IP address in the filenames
 VirtualDocumentRootIP "/www/hosts/%0/docs"
 VirtualScriptAliasIP  "/www/hosts/%0/cgi-bin"</pre>


 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="rewrite" id="rewrite">Mass virtual hosts with
 mod_rewrite</a></h2>

 <p>
 Mass virtual hosting may also be accomplished using
 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>, either using simple <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives, or using more
 complicated techniques such as storing the vhost definitions externally
 and accessing them via <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>. These techniques are
 discussed in the <a href="../rewrite/vhosts.html">rewrite
 documentation</a>.</p>
 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="macro" id="macro">Mass virtual hosts with mod_macro</a></h2>

 <p>Another option for dynamically generated virtual hosts is
 <code class="module"><a href="../mod/mod_macro.html">mod_macro</a></code>, with which you can create a virtualhost
 template, and invoke it for multiple hostnames. An example of this is
 provided in the <strong>Usage</strong> section of the module
 documentation.
 </p>
 </div></div>
 <div class="bottomlang">
 <p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English">&nbsp;en&nbsp;</a> |
 <a href="../fr/vhosts/mass.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a> |
 <a href="../ko/vhosts/mass.html" hreflang="ko" rel="alternate" title="Korean">&nbsp;ko&nbsp;</a> |
 <a href="../tr/vhosts/mass.html" hreflang="tr" rel="alternate" title="Türkçe">&nbsp;tr&nbsp;</a></p>
 </div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&amp;A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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	<div class="toplang">
	<p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English"> en </a> \|
	<a href="../fr/vhosts/mass.html" hreflang="fr" rel="alternate" title="Français"> fr </a> \|
	<a href="../ko/vhosts/mass.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> \|
	<a href="../tr/vhosts/mass.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
	</div>


	<p>This document describes how to efficiently serve an
	arbitrary number of virtual hosts with the Apache HTTP Server. A
	<a href="../rewrite/vhosts.html">separate document</a> discusses using
	<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to create dynamic mass virtual hosts.
	</p>

	</div>
	<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#motivation">Motivation</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#overview">Overview</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#simple">Dynamic Virtual Hosts with
	mod_vhost_alias</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#homepages">Simplified Dynamic Virtual Hosts</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#combinations">Using Multiple Virtual
	Hosting Systems on the Same Server</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#ipbased">More Efficient IP-Based Virtual Hosting</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#rewrite">Mass virtual hosts with
	mod_rewrite</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#macro">Mass virtual hosts with mod_macro</a></li>
	</ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
	<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="motivation" id="motivation">Motivation</a></h2>

	<p>The techniques described here are of interest if your
	<code>httpd.conf</code> contains many
	<code><VirtualHost></code> sections that are
	substantially the same, for example:</p>

	<pre class="prettyprint lang-config"><VirtualHost 111.22.33.44>
	ServerName customer-1.example.com
	DocumentRoot "/www/hosts/customer-1.example.com/docs"
	ScriptAlias "/cgi-bin/" "/www/hosts/customer-1.example.com/cgi-bin"
	</VirtualHost>

	<VirtualHost 111.22.33.44>
	ServerName customer-2.example.com
	DocumentRoot "/www/hosts/customer-2.example.com/docs"
	ScriptAlias "/cgi-bin/" "/www/hosts/customer-2.example.com/cgi-bin"
	</VirtualHost>

	<VirtualHost 111.22.33.44>
	ServerName customer-N.example.com
	DocumentRoot "/www/hosts/customer-N.example.com/docs"
	ScriptAlias "/cgi-bin/" "/www/hosts/customer-N.example.com/cgi-bin"
	</VirtualHost></pre>


	<p>We wish to replace these multiple
	<code><VirtualHost></code> blocks with a mechanism
	that works them out dynamically. This has a number of
	advantages:</p>

	<ol>
	<li>Your configuration file is smaller, so Apache starts
	more quickly and uses less memory. Perhaps more importantly, the
	smaller configuration is easier to maintain, and leaves less room
	for errors.</li>

	<li>Adding virtual hosts is simply a matter of creating the
	appropriate directories in the filesystem and entries in the
	DNS - you don't need to reconfigure or restart Apache.</li>
	</ol>

	<p>The main disadvantage is that you cannot have a different log file for
	each virtual host; however, if you have many virtual hosts, doing
	this can be a bad idea anyway, because of the <a href="fd-limits.html">number of file descriptors needed</a>.
	It is better to <a href="../logs.html#piped">log to a pipe or a fifo</a>,
	and arrange for the process at the other end to split up the log
	files into one per virtual host. One example of such a process can
	be found in the <a href="../programs/split-logfile.html">split-logfile</a>
	utility.</p>

	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="overview" id="overview">Overview</a></h2>

	<p>A virtual host is defined by two pieces of information: its
	IP address, and the contents of the <code>Host:</code> header
	in the HTTP request. The dynamic mass virtual hosting technique
	used here is based on automatically inserting this information into the
	pathname of the file that is used to satisfy the request. This
	can be most easily done by using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code>
	with Apache httpd. Alternatively,
	<a href="../rewrite/vhosts.html">mod_rewrite can
	be used</a>.</p>
	<p>Both of these modules are disabled by default; you must enable
	one of them when configuring and building Apache httpd if you want to
	use this technique.</p>

	<p>A couple of things need to be determined from the request in
	order to make the dynamic
	virtual host look like a normal one. The most important is the
	server name, which is used by the server to generate
	self-referential URLs etc. It is configured with the
	<code>ServerName</code> directive, and it is available to CGIs
	via the <code>SERVER_NAME</code> environment variable. The
	actual value used at run time is controlled by the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code>
	setting. With <code>UseCanonicalName Off</code>, the server name
	is taken from the contents of the <code>Host:</code> header in the
	request. With <code>UseCanonicalName DNS</code>, it is taken from a
	reverse DNS lookup of the virtual host's IP address. The former
	setting is used for name-based dynamic virtual hosting, and the
	latter is used for IP-based hosting. If httpd cannot work out
	the server name because there is no <code>Host:</code> header,
	or the DNS lookup fails, then the value configured with
	<code>ServerName</code> is used instead.</p>

	<p>The other thing to determine is the document root (configured
	with <code>DocumentRoot</code> and available to CGI scripts via the
	<code>DOCUMENT_ROOT</code> environment variable). In a normal
	configuration, this is used by the core module when
	mapping URIs to filenames, but when the server is configured to
	do dynamic virtual hosting, that job must be taken over by another
	module (either <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> or
	<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>), which has a different way of doing
	the mapping. Neither of these modules is responsible for
	setting the <code>DOCUMENT_ROOT</code> environment variable so
	if any CGIs or SSI documents make use of it, they will get a
	misleading value.</p>

	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="simple" id="simple">Dynamic Virtual Hosts with
	mod_vhost_alias</a></h2>

	<p>This extract from <code>httpd.conf</code> implements the
	virtual host arrangement outlined in the <a href="#motivation">Motivation</a> section above
	using <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code>.</p>

	<pre class="prettyprint lang-config"># get the server name from the Host: header
	UseCanonicalName Off

	# this log format can be split per-virtual-host based on the first field
	# using the split-logfile utility.
	LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
	CustomLog "logs/access_log" vcommon

	# include the server name in the filenames used to satisfy requests
	VirtualDocumentRoot "/www/hosts/%0/docs"
	VirtualScriptAlias "/www/hosts/%0/cgi-bin"</pre>


	<p>This configuration can be changed into an IP-based virtual
	hosting solution by just turning <code>UseCanonicalName
	Off</code> into <code>UseCanonicalName DNS</code>. The server
	name that is inserted into the filename is then derived from
	the IP address of the virtual host. The variable <code>%0</code>
	references the requested servername, as indicated in the
	<code>Host:</code> header.</p>

	<p>See the <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation for more usage
	examples.</p>

	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="homepages" id="homepages">Simplified Dynamic Virtual Hosts</a></h2>

	<p>This is an adjustment of the above system, tailored for an
	ISP's web hosting server. Using <code>%2</code>,
	we can select substrings of the server name to
	use in the filename so that, for example, the documents for
	<code>www.user.example.com</code> are found in
	<code>/home/user/www</code>. It uses a single <code>cgi-bin</code>
	directory instead of one per virtual host.</p>

	<pre class="prettyprint lang-config">UseCanonicalName Off

	LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon
	CustomLog "logs/access_log" vcommon

	# include part of the server name in the filenames
	VirtualDocumentRoot "/home/%2/www"

	# single cgi-bin directory
	ScriptAlias "/cgi-bin/" "/www/std-cgi/"</pre>


	<p>There are examples of more complicated
	<code>VirtualDocumentRoot</code> settings in the
	<code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> documentation.</p>

	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="combinations" id="combinations">Using Multiple Virtual
	Hosting Systems on the Same Server</a></h2>

	<p>With more complicated setups, you can use httpd's normal
	<code><VirtualHost></code> directives to control the
	scope of the various virtual hosting configurations. For
	example, you could have one IP address for general customers' homepages,
	and another for commercial customers, with the following setup.
	This can be combined with conventional
	<code><VirtualHost></code> configuration sections, as shown
	below.</p>

	<pre class="prettyprint lang-config">UseCanonicalName Off

	LogFormat "%V %h %l %u %t \"%r\" %s %b" vcommon

	<Directory "/www/commercial">
	Options FollowSymLinks
	AllowOverride All
	</Directory>

	<Directory "/www/homepages">
	Options FollowSymLinks
	AllowOverride None
	</Directory>

	<VirtualHost 111.22.33.44>
	ServerName www.commercial.example.com

	CustomLog "logs/access_log.commercial" vcommon

	VirtualDocumentRoot "/www/commercial/%0/docs"
	VirtualScriptAlias "/www/commercial/%0/cgi-bin"
	</VirtualHost>

	<VirtualHost 111.22.33.45>
	ServerName www.homepages.example.com

	CustomLog "logs/access_log.homepages" vcommon

	VirtualDocumentRoot "/www/homepages/%0/docs"
	ScriptAlias "/cgi-bin/" "/www/std-cgi/"
	</VirtualHost></pre>


	<div class="note">
	<h3>Note</h3>
	<p>If the first VirtualHost block does <em>not</em> include a
	<code class="directive"><a href="../mod/core.html#servername">ServerName</a></code> directive, the reverse
	DNS of the relevant IP will be used instead.
	If this is not the server name you
	wish to use, a bogus entry (eg. <code>ServerName
	none.example.com</code>) can be added to get around this
	behaviour.</p>
	</div>

	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="ipbased" id="ipbased">More Efficient IP-Based Virtual Hosting</a></h2>

	<p>The configuration changes suggested to turn <a href="#simple">the first
	example</a> into an IP-based virtual hosting setup result in
	a rather inefficient setup. A new DNS lookup is required for every
	request. To avoid this overhead, the filesystem can be arranged to
	correspond to the IP addresses, instead of to the host names, thereby
	negating the need for a DNS lookup. Logging will also have to be adjusted
	to fit this system.</p>

	<pre class="prettyprint lang-config"># get the server name from the reverse DNS of the IP address
	UseCanonicalName DNS

	# include the IP address in the logs so they may be split
	LogFormat "%A %h %l %u %t \"%r\" %s %b" vcommon
	CustomLog "logs/access_log" vcommon

	# include the IP address in the filenames
	VirtualDocumentRootIP "/www/hosts/%0/docs"
	VirtualScriptAliasIP "/www/hosts/%0/cgi-bin"</pre>


	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="rewrite" id="rewrite">Mass virtual hosts with
	mod_rewrite</a></h2>

	<p>
	Mass virtual hosting may also be accomplished using
	<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>, either using simple <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives, or using more
	complicated techniques such as storing the vhost definitions externally
	and accessing them via <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>. These techniques are
	discussed in the <a href="../rewrite/vhosts.html">rewrite
	documentation</a>.</p>
	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="macro" id="macro">Mass virtual hosts with mod_macro</a></h2>

	<p>Another option for dynamically generated virtual hosts is
	<code class="module"><a href="../mod/mod_macro.html">mod_macro</a></code>, with which you can create a virtualhost
	template, and invoke it for multiple hostnames. An example of this is
	provided in the <strong>Usage</strong> section of the module
	documentation.
	</p>
	</div></div>
	<div class="bottomlang">
	<p><span>Available Languages: </span><a href="../en/vhosts/mass.html" title="English"> en </a> \|
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