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diff --git a/APACHE_1_3_42/htdocs/manual/vhosts/virtual-host.html b/APACHE_1_3_42/htdocs/manual/vhosts/virtual-host.html new file mode 100644 index 0000000000..e8a88143c5 --- /dev/null +++ b/APACHE_1_3_42/htdocs/manual/vhosts/virtual-host.html @@ -0,0 +1,239 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> + +<html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org" /> + + <title>Apache Server Virtual Host Support</title> + </head> + <!-- Background white, links blue (unvisited), navy (visited), red (active) --> + + <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" + vlink="#000080" alink="#FF0000"> + <!--#include virtual="header.html" --> + + <h1 align="CENTER">Virtual Host Support</h1> + <strong>See Also:</strong> <a href="host.html">Non-IP based + virtual hosts</a> + + <h2>What are virtual hosts?</h2> + This is the ability of a single machine to be a web server for + multiple domains. For example, an Internet service provider + might have a machine called <code>www.serve.com</code> which + provides Web space for several organizations including, say, + <em>smallco</em> and <em>baygroup</em>. Ordinarily, these + groups would be given parts of the Web tree on www.serve.com. + So smallco's home page would have the URL + + <blockquote> + http://www.serve.com/smallco/ + </blockquote> + and baygroup's home page would have the URL + + <blockquote> + http://www.serve.com/baygroup/ + </blockquote> + + <p>For esthetic reasons, however, both organizations would + rather their home pages appeared under their own names rather + than that of the service provider's; but they do not want to + set up their own Internet links and servers.</p> + + <p>Virtual hosts are the solution to this problem. smallco and + baygroup would have their own Internet name registrations, + <code>www.smallco.com</code> and <code>www.baygroup.org</code> + respectively. These hostnames would both correspond to the + service provider's machine (www.serve.com). Thus smallco's home + page would now have the URL</p> + + <blockquote> + http://www.smallco.com/ + </blockquote> + and baygroup's home page would have the URL + + <blockquote> + http://www.baygroup.org/ + </blockquote> + + <h2>System requirements</h2> + Due to limitations in the HTTP/1.0 protocol, the web server + <strong>must have a different IP address for each virtual + host</strong>. This can be achieved by the machine having + several physical network connections, or by use of a <a + href="../misc/vif-info.html">virtual interface</a> on some + operating systems. + + <h2>How to set up Apache</h2> + 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>Use multiple daemons when:</p> + + <ul> + <li>The different virtual hosts need very different httpd + configurations, such as different values for: <a + href="../mod/core.html#servertype">ServerType</a>, <a + href="../mod/core.html#user">User</a>, <a + href="../mod/core.html#group">Group</a>, <a + href="../mod/mod_mime.html#typesconfig">TypesConfig</a> or <a + href="../mod/core.html#serverroot">ServerRoot</a>.</li> + + <li>The machine does not process a very high request + rate.</li> + </ul> + Use a single daemon when: + + <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> + + <h2>Setting up multiple daemons</h2> + Create a separate httpd installation for each virtual host. For + each installation, use the <a + href="../mod/core.html#bindaddress">BindAddress</a> directive + in the configuration file to select which IP address (or + virtual host) that daemon services. <em>E.g.</em>, + + <blockquote> + <code>BindAddress www.smallco.com</code> + </blockquote> + This hostname can also be given as an IP address. + + <h2>Setting up a single daemon</h2> + For this case, a single httpd will service requests for all the + virtual hosts. The <a + href="../mod/core.html#virtualhost">VirtualHost</a> directive + in the configuration file is used to set the values of <a + href="../mod/core.html#serveradmin">ServerAdmin</a>, <a + href="../mod/core.html#servername">ServerName</a>, <a + href="../mod/core.html#documentroot">DocumentRoot</a>, <a + href="../mod/core.html#errorlog">ErrorLog</a> and <a + href="../mod/mod_log_config.html#transferlog">TransferLog</a> + configuration directives to different values for each virtual + host. <em>E.g.</em>, + + <blockquote> + <code><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><br /> + </code> + </blockquote> + This VirtualHost hostnames can also be given as IP addresses. + + <p>Almost <strong>ANY</strong> configuration directive can be + put in the VirtualHost directive, with the exception of <a + href="../mod/core.html#servertype">ServerType</a>, <a + href="../mod/core.html#user">User</a>, <a + href="../mod/core.html#group">Group</a>, <a + href="../mod/core.html#startservers">StartServers</a>, <a + href="../mod/core.html#maxspareservers">MaxSpareServers</a>, <a + href="../mod/core.html#minspareservers">MinSpareServers</a>, <a + href="../mod/core.html#maxrequestsperchild">MaxRequestsPerChild</a>, + <a href="../mod/core.html#bindaddress">BindAddress</a>, <a + href="../mod/core.html#pidfile">PidFile</a>, <a + href="../mod/mod_mime.html#typesconfig">TypesConfig</a>, and <a + href="../mod/core.html#serverroot">ServerRoot</a>.</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> + + <h2>File Handle/Resource Limits:</h2> + When using a large number of Virtual Hosts, Apache may run out + of available file descriptors if each Virtual Host specifies + different log files. The total number of file descriptors used + by Apache is one for each distinct error log file, one for + every other log file directive, plus 10-20 for internal use. + Unix operating systems limit the number of file descriptors + that may be used by a process; the limit is typically 64, and + may usually be increased up to a large hard-limit. + + <p>Although Apache attempts to increase the limit as required, + this may not work if:</p> + + <ol> + <li>Your system does not provide the setrlimit() system + call.</li> + + <li>The setrlimit(RLIMIT_NOFILE) call does not function on + your system (such as Solaris 2.3)</li> + + <li>The number of file descriptors required exceeds the hard + limit.</li> + + <li>Your system imposes other limits on file descriptors, + such as a limit on stdio streams only using file descriptors + below 256. (Solaris 2)</li> + </ol> + In the event of problems you can: + + <ul> + <li>Reduce the number of log files; don't specify log files + in the VirtualHost sections, but only log to the main log + files.</li> + + <li> + If you system falls into 1 or 2 (above), then increase the + file descriptor limit before starting Apache, using a + script like + + <blockquote> + <code>#!/bin/sh<br /> + ulimit -S -n 100<br /> + exec httpd</code> + </blockquote> + </li> + </ul> + The have been reports that Apache may start running out of + resources allocated for the root process. This will exhibit + itself as errors in the error log like "unable to fork". There + are two ways you can bump this up: + + <ol> + <li>Have a <code>csh</code> script wrapper around httpd which + sets the "rlimit" to some large number, like 512.</li> + + <li> + Edit http_main.c to add calls to setrlimit() from main(), + along the lines of +<pre> + struct rlimit rlp; + + rlp.rlim_cur = rlp.rlim_max = 512; + if (setrlimit(RLIMIT_NPROC, &rlp)) { + fprintf(stderr, "setrlimit(RLIMIT_NPROC) failed.\n"); + exit(1); + } +</pre> + (thanks to "Aaron Gifford <agifford@InfoWest.COM>" + for the patch) + </li> + </ol> + The latter will probably manifest itself in a later version of + Apache. <!--#include virtual="footer.html" --> + </body> +</html> + |