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-
- <manualpage metafile="ip-based.xml.meta">
- <parentdocument href="./">Virtual Hosts</parentdocument>
- <title>Apache IP-based Virtual Host Support</title>
-
- <seealso>
- <a href="name-based.html">Name-based Virtual Hosts Support</a>
- </seealso>
-
- <section id="requirements"><title>System requirements</title>
-
- <p>As the term <cite>IP-based</cite> indicates, the server
- <strong>must have a different IP address for each IP-based
- virtual host</strong>. This can be achieved by the machine
- having several physical network connections, or by use of
- virtual interfaces which are supported by most modern operating
- systems (see system documentation for details, these are
- frequently called "ip aliases", and the "ifconfig" command is
- most commonly used to set them up).</p>
-
- </section>
-
- <section id="howto"><title>How to set up Apache</title>
-
- <p>There are two ways of configuring apache to support multiple
- hosts. Either by running a separate httpd daemon for each
- hostname, or by running a single daemon which supports all the
- virtual hosts.</p>
-
- <p>Use multiple daemons when:</p>
-
- <ul>
- <li>There are security partitioning issues, such as company1
- does not want anyone at company2 to be able to read their
- data except via the web. In this case you would need two
- daemons, each running with different <directive
- module="mpm_common">User</directive>, <directive
- module="mpm_common">Group</directive>, <directive
- module="mpm_common">Listen</directive>, and <directive
- module="core">ServerRoot</directive> settings.</li>
-
- <li>You can afford the memory and <a
- href="../misc/descriptors.html">file descriptor
- requirements</a> of listening to every IP alias on the
- machine. It's only possible to <directive
- module="mpm_common">Listen</directive> to the "wildcard"
- address, or to specific addresses. So if you have a need to
- listen to a specific address for whatever reason, then you
- will need to listen to all specific addresses. (Although one
- httpd could listen to N-1 of the addresses, and another could
- listen to the remaining address.)</li>
- </ul>
-
- <p>Use a single daemon when:</p>
-
- <ul>
- <li>Sharing of the httpd configuration between virtual hosts
- is acceptable.</li>
-
- <li>The machine services a large number of requests, and so
- the performance loss in running separate daemons may be
- significant.</li>
- </ul>
-
- </section>
-
- <section id="multiple"><title>Setting up multiple daemons</title>
-
- <p>Create a separate httpd installation for each virtual host. For
- each installation, use the <directive
- module="mpm_common">Listen</directive> directive in the
- configuration file to select which IP address (or virtual host)
- that daemon services. e.g.</p>
-
- <example>
- Listen www.smallco.com:80
- </example>
-
- <p>It is recommended that you use an IP address instead of a
- hostname (see <a href="../dns-caveats.html">DNS caveats</a>).</p>
-
- </section>
-
- <section id="single"><title>Setting up a single daemon
- with virtual hosts</title>
-
- <p>For this case, a single httpd will service requests for the
- main server and all the virtual hosts. The <directive
- module="core">VirtualHost</directive> directive
- in the configuration file is used to set the values of <directive
- module="core">ServerAdmin</directive>, <directive
- module="core">ServerName</directive>, <directive
- module="core">DocumentRoot</directive>, <directive
- module="core">ErrorLog</directive> and <directive
- module="mod_log_config">TransferLog</directive>
- or <directive module="mod_log_config">CustomLog</directive>
- configuration directives to different values for each virtual
- host. e.g.</p>
-
- <example>
- <VirtualHost www.smallco.com><br />
- ServerAdmin webmaster@mail.smallco.com<br />
- DocumentRoot /groups/smallco/www<br />
- ServerName www.smallco.com<br />
- ErrorLog /groups/smallco/logs/error_log<br />
- TransferLog /groups/smallco/logs/access_log<br />
- </VirtualHost><br />
- <br />
- <VirtualHost www.baygroup.org><br />
- ServerAdmin webmaster@mail.baygroup.org<br />
- DocumentRoot /groups/baygroup/www<br />
- ServerName www.baygroup.org<br />
- ErrorLog /groups/baygroup/logs/error_log<br />
- TransferLog /groups/baygroup/logs/access_log<br />
- </VirtualHost>
- </example>
-
- <p>It is recommended that you use an IP address instead of a
- hostname (see <a href="../dns-caveats.html">DNS caveats</a>).</p>
-
- <p>Almost <strong>any</strong> configuration directive can be
- put in the VirtualHost directive, with the exception of
- directives that control process creation and a few other
- directives. To find out if a directive can be used in the
- VirtualHost directive, check the <a
- href="../mod/directive-dict.html#Context">Context</a> using the
- <a href="../mod/directives.html">directive index</a>.</p>
-
- <p><directive module="mpm_common">User</directive> and <directive
- module="mpm_common">Group</directive> may be used inside a
- VirtualHost directive if the <a href="../suexec.html">suEXEC
- wrapper</a> is used.</p>
-
- <p><em>SECURITY:</em> When specifying where to write log files,
- be aware of some security risks which are present if anyone
- other than the user that starts Apache has write access to the
- directory where they are written. See the <a
- href="../misc/security_tips.html">security tips</a> document
- for details.</p>
-
- </section>
- </manualpage>
-