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diff --git a/docs/manual/vhosts/name-based.xml b/docs/manual/vhosts/name-based.xml new file mode 100644 index 0000000000..6cc9a1f7e5 --- /dev/null +++ b/docs/manual/vhosts/name-based.xml @@ -0,0 +1,234 @@ +<?xml version='1.0' encoding='UTF-8' ?> +<!DOCTYPE manualpage SYSTEM "../style/manualpage.dtd"> +<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?> + +<manualpage> +<relativepath href=".."/> + +<title>Name-based Virtual Host Support</title> + +<summary> + + <p>This document describes when and how to use name-based virtual hosts.</p> + +</summary> + +<seealso><a href="ip-based.html">IP-based Virtual Host Support</a></seealso> +<seealso><a href="details.html">An In-Depth Discussion of Virtual Host Matching</a></seealso> +<seealso><a href="mass.html">Dynamically configured mass virtual hosting</a></seealso> +<seealso><a href="examples.html">Virtual Host examples for common setups</a></seealso> +<seealso><a href="examples.html#serverpath">ServerPath configuration example</a></seealso> + +<section id="namevip"><title>Name-based vs. IP-based Virtual Hosts</title> + + <p>IP-based virtual hosts use the IP address of the connection to + determine the correct virtual host to serve. Therefore you need to + have a separate IP address for each host. With name-based virtual + hosting, the server relies on the client to report the hostname as + part of the HTTP headers. Using this technique, many different hosts + can share the same IP address.</p> + + <p>Name-based virtual hosting is usually simpler, since you need + only configure your DNS server to map each hostname to the correct + IP address and then configure the Apache HTTP Server to recognize + the different hostnames. Name-based virtual hosting also eases + the demand for scarce IP addresses. Therefore you should use + name-based virtual hosting unless there is a specific reason to + choose IP-based virtual hosting. Some reasons why you might consider + using IP-based virtual hosting:</p> + + <ul> + <li>Some ancient clients are not compatible with name-based virtual + hosting. For name-based virtual hosting to work, the client must send + the HTTP Host header. This is required by HTTP/1.1, and is + implemented by all modern HTTP/1.0 browsers as an extension. If you + need to support obsolete clients and still use name-based virtual + hosting, a possible technique is discussed at the end of this + document.</li> + + <li>Name-based virtual hosting cannot be used with SSL secure servers + because of the nature of the SSL protocol.</li> + + <li>Some operating systems and network equipment implement bandwidth + management techniques that cannot differentiate between hosts unless + they are on separate IP addresses.</li> + </ul> + +</section> + +<section id="using"><title>Using Name-based Virtual Hosts</title> + +<related> + <modulelist> + <module>core</module> + </modulelist> + + <directivelist> + <directive module="core">DocumentRoot</directive> + <directive module="core">NameVirtualHost</directive> + <directive module="core">ServerAlias</directive> + <directive module="core">ServerName</directive> + <directive module="core">ServerPath</directive> + <directive module="core">VirtualHost</directive> + </directivelist> +</related> + + <p>To use name-based virtual hosting, you must designate the IP + address (and possibly port) on the server that will be accepting + requests for the hosts. This is configured using the <directive + module="core">NameVirtualHost</directive> directive. + In the normal case where any and all IP addresses on the server should + be used, you can use <code>*</code> as the argument to + <code>NameVirtualHost</code>. Note that mentioning an IP address in a + <code>NameVirtualHost</code> directive does not automatically make the + server listen to that IP address. See <a href="../bind.html">Setting + which addresses and ports Apache uses</a> for more details. In addition, + any IP address specified here must be associated with a network interface + on the server.</p> + + <p>The next step is to create a <directive type="section" + module="core">VirtualHost</directive> block for + each different host that you would like to serve. The argument to the + <code><VirtualHost></code> directive should be the same as the + argument to the <code>NameVirtualHost</code> directive (ie, an IP + address, or <code>*</code> for all addresses). Inside each + <code><VirtualHost></code> block, you will need at minimum a / + <directive module="core">ServerName</directive> directive to + designate which host is served and a <directive + module="core">DocumentRoot</directive> directive to + show where in the filesystem the content for that host lives.</p> + + <p>If you are adding virtual hosts to an existing web server, you + must also create a <VirtualHost> block for the existing host. + The <code>ServerName</code> and <code>DocumentRoot</code> included in + this virtual host should be the same as the global + <code>ServerName</code> and <code>DocumentRoot</code>. List this + virtual host first in the configuration file so that it will act as + the default host.</p> + + <p>For example, suppose that you are serving the domain + <code>www.domain.tld</code> and you wish to add the virtual host + <code>www.otherdomain.tld</code>, which points at the same IP address. + Then you simply add the following to <code>httpd.conf</code>:</p> + + <example> +<pre> + NameVirtualHost * + + <VirtualHost *> + ServerName www.domain.tld + DocumentRoot /www/domain + </VirtualHost> + + <VirtualHost *> + ServerName www.otherdomain.tld + DocumentRoot /www/otherdomain + </VirtualHost> +</pre> + </example> + + <p>You can alternatively specify an explicit IP address in place of + the * in both the <code>NameVirtualHost</code> and + <code><VirtualHost></code> directives.</p> + + <p>Many servers want to be accessible by more than one name. This is + possible with the <directive module="core">ServerAlias</directive> + directive, placed inside the <VirtualHost> section. For + example if you add this to the first <VirtualHost> block + above</p> + + <example> + ServerAlias domain.tld *.domain.tld + </example> + + <p>then requests for all hosts in the <code>domain.tld</code> domain + will be served by the <code>www.domain.tld</code> virtual host. The + wildcard characters * and ? can be used to match names. Of course, + you can't just make up names and place them in <code>ServerName</code> + or <code>ServerAlias</code>. You must first have your DNS server + properly configured to map those names to an IP address associated + with your server.</p> + + <p>Finally, you can fine-tune the configuration of the virtual hosts + by placing other directives inside the + <code><VirtualHost></code> containers. Most directives can be + placed in these containers and will then change the configuration only + of the relevant virtual host. To find out if a particular directive + is allowed, check the <a + href="../mod/directive-dict.html#Context">Context</a> of the + directive. Configuration directives set in the <em>main server + context</em> (outside any <code><VirtualHost></code> container) + will be used only if they are not overriden by the virtual host + settings.</p> + + <p>Now when a request arrives, the server will first check if it is + using an IP address that matches the <code>NameVirtualHost</code>. If + it is, then it will look at each <code><VirtualHost></code> + section with a matching IP address and try to find one where the + <code>ServerName</code> or <code>ServerAlias</code> matches the + requested hostname. If it finds one, then it uses the configuration + for that server. If no matching virtual host is found, then + <strong>the first listed virtual host</strong> that matches the IP + address will be used.</p> + + <p>As a consequence, the first listed virtual host is the + <em>default</em> virtual host. The <code>DocumentRoot</code> from the + <em>main server</em> will <strong>never</strong> be used when an IP + address matches the <code>NameVirtualHost</code> directive. If you + would like to have a special configuration for requests that do not + match any particular virtual host, simply put that configuration in a + <code><VirtualHost></code> container and list it first in the + configuration file.</p> + +</section> + +<section id=""><title>Compatibility with Older Browsers</title> + + <p>As mentioned earlier, there are some clients + who do not send the required data for the name-based virtual + hosts to work properly. These clients will always be sent the + pages from the first virtual host listed for that IP address + (the <cite>primary</cite> name-based virtual host).</p> + + <p>There is a possible workaround with the <directive + module="core">ServerPath</directive> + directive, albeit a slightly cumbersome one:</p> + + <p>Example configuration:</p> + + <example> + NameVirtualHost 111.22.33.44<br /> + <br /> + <VirtualHost 111.22.33.44><br /> + ServerName www.domain.tld<br /> + ServerPath /domain<br /> + DocumentRoot /web/domain<br /> + </VirtualHost><br /> + </example> + + <p>What does this mean? It means that a request for any URI + beginning with "<code>/domain</code>" will be served from the + virtual host <code>www.domain.tld</code> This means that the + pages can be accessed as + <code>http://www.domain.tld/domain/</code> for all clients, + although clients sending a <code>Host:</code> header can also + access it as <code>http://www.domain.tld/</code>.</p> + + <p>In order to make this work, put a link on your primary + virtual host's page to + <code>http://www.domain.tld/domain/</code> Then, in the virtual + host's pages, be sure to use either purely relative links + (<em>e.g.</em>, "<code>file.html</code>" or + "<code>../icons/image.gif</code>" or links containing the + prefacing <code>/domain/</code> (<em>e.g.</em>, + "<code>http://www.domain.tld/domain/misc/file.html</code>" or + "<code>/domain/misc/file.html</code>").</p> + + <p>This requires a bit of discipline, but adherence to these + guidelines will, for the most part, ensure that your pages will + work with all browsers, new and old.</p> + +</section> +</manualpage> + + |