docs/manual/bind.html.en - httpd - Git at Google

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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>

     <p>When Apache starts, it connects to some port and address on
     the local machine and waits for incoming requests. By default,
     it listens to all addresses on the machine.  However, it needs to
     be told to listen to specific ports, 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>

     <p>The <code>Listen</code> directive tells the server to accept
     incoming requests only on the specified port or
     address-and-port combinations. If only a port number is
     specified in the <code>Listen</code> directive, the server
     listens to the given port on all interfaces. If an IP address
     is given as well as a port, the server will listen on the given
     port and interface. 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>
     IPv6 addresses must be surrounded in square brackets, as in the
     following example:
 <pre>
    Listen [fe80::a00:20ff:fea7:ccea]:80
 </pre>

     <h2>Special IPv6 considerations</h2>

     When APR supports IPv6, Apache will create IPv6-capable listening
     sockets by default (i.e., when no IP address is specified on the
     Listen directive).  In other words, when APR supports IPv6,
 <pre>
    Listen 80
 </pre>
     is equivalent to
 <pre>
    Listen [::]:80
 </pre>
     When APR does not support IPv6,
 <pre>
    Listen 80
 </pre>
     is equivalent to
 <pre>
    Listen 0.0.0.0:80
 </pre>
     On some platforms, such as NetBSD, binding to the IPv6 wildcard address
     ("::") does not allow Apache to accept connections on IPv4 interfaces.
     In this situation, multiple Listen directives are required, as shown
     below:
 <pre>
    Listen 0.0.0.0:80
    Listen [::]:80
 </pre>
     Apache does not currently detect this, so the Listen statements must
     be edited manually by the administrator.

     <h2>How this works with Virtual Hosts</h2>

     <p>Listen does not implement Virtual Hosts. It only tells the
     main server what addresses and ports to listen to. If no
     &lt;VirtualHost&gt; directives are used, the server will behave
     the same for all accepted requests. However,
     &lt;VirtualHost&gt; can be used to specify a different behavior
     for one or more of the addresses and ports. To implement a
     VirtualHost, the server must first be told to listen to the
     address and port to be used. Then a &lt;VirtualHost&gt; section
     should be created for a specified address and port to set the
     behavior of this virtual host. Note that if the
     &lt;VirtualHost&gt; is set for an address and port that the
     server is not listening to, it cannot be accessed.</p>

     <h2>See also</h2>
     See also the documentation on <a
     href="mod/mpm_common.html#listen">Listen directive</a>, <a
     href="vhosts/">Virtual Hosts</a>, <a
     href="dns-caveats.html">DNS Issues</a> and <a
     href="mod/core.html#virtualhost">&lt;VirtualHost&gt;
     section</a>. <!--#include virtual="footer.html" -->
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	<head>
	<meta name="generator" content="HTML Tidy, see www.w3.org" />

	<title>Setting which addresses and ports Apache uses</title>
	</head>
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	<body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
	vlink="#000080" alink="#FF0000">
	<!--#include virtual="header.html" -->

	<h1 align="CENTER">Setting which addresses and ports Apache
	uses</h1>

	<p>When Apache starts, it connects to some port and address on
	the local machine and waits for incoming requests. By default,
	it listens to all addresses on the machine. However, it needs to
	be told to listen to specific ports, 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>

	<p>The <code>Listen</code> directive tells the server to accept
	incoming requests only on the specified port or
	address-and-port combinations. If only a port number is
	specified in the <code>Listen</code> directive, the server
	listens to the given port on all interfaces. If an IP address
	is given as well as a port, the server will listen on the given
	port and interface. 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>
	IPv6 addresses must be surrounded in square brackets, as in the
	following example:
	<pre>
	Listen [fe80::a00:20ff:fea7:ccea]:80
	</pre>

	<h2>Special IPv6 considerations</h2>

	When APR supports IPv6, Apache will create IPv6-capable listening
	sockets by default (i.e., when no IP address is specified on the
	Listen directive). In other words, when APR supports IPv6,
	<pre>
	Listen 80
	</pre>
	is equivalent to
	<pre>
	Listen [::]:80
	</pre>
	When APR does not support IPv6,
	<pre>
	Listen 80
	</pre>
	is equivalent to
	<pre>
	Listen 0.0.0.0:80
	</pre>
	On some platforms, such as NetBSD, binding to the IPv6 wildcard address
	("::") does not allow Apache to accept connections on IPv4 interfaces.
	In this situation, multiple Listen directives are required, as shown
	below:
	<pre>
	Listen 0.0.0.0:80
	Listen [::]:80
	</pre>
	Apache does not currently detect this, so the Listen statements must
	be edited manually by the administrator.

	<h2>How this works with Virtual Hosts</h2>

	<p>Listen does not implement Virtual Hosts. It only tells the
	main server what addresses and ports to listen to. 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 first be told to listen to the
	address and port to be used. Then a <VirtualHost> section
	should be created for a specified address and port to set the
	behavior of this virtual host. Note that if the
	<VirtualHost> is set for an address and port that the
	server is not listening to, it cannot be accessed.</p>

	<h2>See also</h2>
	See also the documentation on <a
	href="mod/mpm_common.html#listen">Listen directive</a>, <a
	href="vhosts/">Virtual Hosts</a>, <a
	href="dns-caveats.html">DNS Issues</a> and <a
	href="mod/core.html#virtualhost"><VirtualHost>
	section</a>. <!--#include virtual="footer.html" -->
	</body>
	</html>