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2N/A<manualpage metafile="bind.xml.meta">

2N/A

2N/A <title>Binding</title>

2N/A

2N/A <summary>

2N/A <p>Configuring Apache to listen on specific addresses and ports.</p>

2N/A </summary>

2N/A

2N/A <seealso><a href="vhosts/">Virtual Hosts</a></seealso>

12N/A <seealso><a href="dns-caveats.html">DNS Issues</a></seealso>

12N/A

2N/A <section id="overview">

2N/A <title>Overview</title>

2N/A

2N/A <related>

26N/A <modulelist>

26N/A <module>core</module>

2N/A <module>mpm_common</module>

26N/A </modulelist>

26N/A <directivelist>

26N/A <directive module="core" type="section">VirtualHost</directive>

26N/A <directive module="mpm_common">Listen</directive>

26N/A </directivelist>

26N/A </related>

26N/A

26N/A

26N/A <p>When Apache starts, it binds to some port and address on

26N/A the local machine and waits for incoming requests. By default,

26N/A it listens to all addresses on the machine. However, it may need to

26N/A be told to listen on specific ports, or only on selected

26N/A addresses, or a combination of both. This is often combined with the

26N/A Virtual Host feature, which determines how Apache responds to

26N/A different IP addresses, hostnames and ports.</p>

26N/A

26N/A <p>The <directive module="mpm_common">Listen</directive>

26N/A directive tells the server to accept

26N/A incoming requests only on the specified ports or

26N/A address-and-port combinations. If only a port number is

26N/A specified in the <directive module="mpm_common">Listen</directive>

2N/A directive, the server

26N/A listens to the given port on all interfaces. If an IP address

26N/A is given as well as a port, the server will listen on the given

26N/A port and interface. Multiple <directive

26N/A module="mpm_common">Listen</directive> directives may be used to

26N/A specify a number of addresses and ports to listen on. The

26N/A server will respond to requests from any of the listed

26N/A addresses and ports.</p>

26N/A

26N/A <p>For example, to make the server accept connections on both

26N/A port 80 and port 8000, on all interfaces, use:</p>

26N/A

26N/A <example>

26N/A Listen 80<br />

2N/A Listen 8000

26N/A </example>

26N/A

26N/A <p>To make the server accept connections on port 80 for one interface,

26N/A and port 8000 on another, use</p>

26N/A

26N/A <example>

26N/A Listen 192.0.2.1:80<br />

12N/A Listen 192.0.2.5:8000

26N/A </example>

26N/A

26N/A <p>IPv6 addresses must be enclosed in square brackets, as in the

26N/A following example:</p>

2N/A

26N/A <example>

26N/A Listen [2001:db8::a00:20ff:fea7:ccea]:80

26N/A </example>

2N/A </section>

7N/A

26N/A <section id="ipv6">

21N/A <title>Special IPv6 Considerations</title>

7N/A

26N/A <p>A growing number of platforms implement IPv6, and

26N/A <glossary>APR</glossary> supports IPv6 on most of these platforms,

26N/A allowing Apache to allocate IPv6 sockets, and to handle requests sent

26N/A over IPv6.</p>

26N/A

26N/A <p>One complicating factor for Apache administrators is whether or

26N/A not an IPv6 socket can handle both IPv4 connections and IPv6

26N/A connections. Handling IPv4 connections with an IPv6 socket uses

26N/A IPv4-mapped IPv6 addresses, which are allowed by default on most

26N/A platforms, but are disallowed by default on FreeBSD, NetBSD, and

26N/A OpenBSD, in order to match the system-wide policy on those

26N/A platforms. On systems where it is disallowed by default, a

26N/A special <program>configure</program> parameter can change this behavior

26N/A for Apache.</p>

26N/A

26N/A <p>On the other hand, on some platforms, such as Linux and Tru64, the

7N/A <strong>only</strong> way to handle both IPv6 and IPv4 is to use

26N/A mapped addresses. If you want Apache to handle IPv4 and IPv6 connections

26N/A with a minimum of sockets, which requires using IPv4-mapped IPv6

26N/A addresses, specify the <code>--enable-v4-mapped</code> <program>

26N/A configure</program> option.</p>

26N/A

26N/A <p><code>--enable-v4-mapped</code> is the default on all platforms except

26N/A FreeBSD, NetBSD, and OpenBSD, so this is probably how your Apache was

26N/A built.</p>

26N/A

26N/A <p>If you want Apache to handle IPv4 connections only, regardless of

26N/A what your platform and APR will support, specify an IPv4 address on all

26N/A <directive module="mpm_common">Listen</directive> directives, as in the

26N/A following examples:</p>

26N/A

26N/A <example>

26N/A Listen 0.0.0.0:80<br />

26N/A Listen 192.0.2.1:80

26N/A </example>

26N/A

26N/A <p>If your platform supports it and you want Apache to handle IPv4 and

2N/A IPv6 connections on separate sockets (i.e., to disable IPv4-mapped

26N/A addresses), specify the <code>--disable-v4-mapped</code> <program>

26N/A configure</program> option. <code>--disable-v4-mapped</code> is the

26N/A default on FreeBSD, NetBSD, and OpenBSD.</p>

26N/A </section>

26N/A

26N/A <section id="virtualhost">

26N/A <title>How This Works With Virtual Hosts</title>

26N/A

26N/A <p> The <directive

26N/A module="mpm_common">Listen</directive> directive does not implement

26N/A Virtual Hosts - it only tells the

26N/A main server what addresses and ports to listen on. If no

26N/A <directive module="core" type="section">VirtualHost</directive>

26N/A directives are used, the server will behave

26N/A in the same way for all accepted requests. However,

26N/A <directive module="core" type="section">VirtualHost</directive>

26N/A can be used to specify a different behavior

26N/A for one or more of the addresses or ports. To implement a

26N/A VirtualHost, the server must first be told to listen to the

26N/A address and port to be used. Then a

26N/A <directive module="core" type="section">VirtualHost</directive> section

26N/A should be created for the specified address and port to set the

26N/A behavior of this virtual host. Note that if the

2N/A <directive module="core" type="section">VirtualHost</directive>

26N/A is set for an address and port that the

26N/A server is not listening to, it cannot be accessed.</p>

26N/A </section>

26N/A</manualpage>

26N/A

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