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<title>Setting which addresses and ports Apache uses</title>
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<h1 align="CENTER">Setting which addresses and ports Apache
uses</h1>
<hr />
When Apache starts, it connects to some port and address on the
local machine and waits for incoming requests. By default, it
listens to all addresses on the machine, and to the port as
specified by the <tt>Port</tt> directive in the server
configuration. However, it can be told to listen to more the
one port, or to listen to only selected addresses, or a
combination. This is often combined with the Virtual Host
feature which determines how Apache responds to different IP
addresses, hostnames and ports.
<p>There are two directives used to restrict or specify which
addresses and ports Apache listens to.</p>
<ul>
<li><a href="#bindaddress">BindAddress</a> is used to
restrict the server to listening to a single address, and can
be used to permit multiple Apache servers on the same machine
listening to different IP addresses.</li>
<li><a href="#listen">Listen</a> can be used to make a single
Apache server listen to more than one address and/or
port.</li>
</ul>
<h3><a id="bindaddress" name="bindaddress">BindAddress</a></h3>
<a href="mod/directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> BindAddress <em>[ * |
IP-address | hostname ]</em><br />
<a href="mod/directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a> <code>BindAddress
*</code><br />
<a href="mod/directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="mod/directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core
<p>Makes the server bind to just the specified address. If the
argument is * (an asterisk), the server binds to all interfaces
currently marked as up on the server. The port bound to is set
with the <tt>Port</tt> directive. Only one BindAddress should
be used.</p>
<h3><a id="listen" name="listen">Listen</a></h3>
<a href="mod/directive-dict.html#Syntax"
rel="Help"><strong>Syntax:</strong></a> Listen <em>[ port |
IP-address:port ]</em><br />
<a href="mod/directive-dict.html#Default"
rel="Help"><strong>Default:</strong></a>
<code>none</code><br />
<a href="mod/directive-dict.html#Context"
rel="Help"><strong>Context:</strong></a> server config<br />
<a href="mod/directive-dict.html#Status"
rel="Help"><strong>Status:</strong></a> Core
<p><tt>Listen</tt> can be used instead of <tt>BindAddress</tt>
and <tt>Port</tt>. It tells the server to accept incoming
requests (to listen) on the specified port or address-and-port
combination. If the first format is used, with a port number
only, the server listens on the given port on all interfaces
marked as up, 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>
<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>
<h2>How this works with Virtual Hosts</h2>
<tt>BindAddress</tt> and <tt>Listen</tt> do not implement
Virtual Hosts. They tell the main Apache daemon process what
addresses and ports to bind and listen on. If no
<VirtualHost> directives are used, the server will behave
the same for all accepted requests. However,
<VirtualHost> can be used to specify a different behavior
for one or more of the addresses and ports. To implement a
VirtualHost, the server must:
<ul>
<li>Be told to <tt>Listen</tt> to the desired address and
port</li>
<li>Have a <VirtualHost> section created for the
specified address and port to set the behavior of this
virtual host</li>
</ul>
Note that if the <VirtualHost> is set for an address and
port that the server is not listening to, it cannot be
accessed.
<h2>See also</h2>
See also the documentation on <a href="vhosts/">Virtual
Hosts</a>, <a href="mod/core.html#bindaddress">BindAddress
directive</a>, <a href="mod/core.html#port">Port directive</a>,
<a href="dns-caveats.html">DNS Issues</a> and <a
href="mod/core.html#virtualhost"><VirtualHost>
section</a>. <!--#include virtual="footer.html" -->
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