Virtual Hosting

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One of the more popular services to provide with a web server is to host a virtual domain. Also known as a virtual host, a virtual domain is a complete website with its own domain name, as if it were a standalone machine, but it's hosted on the same machine as other websites. Apache implements this capability in a simple way with directives in the httpd.conf configuration file.

Apache now can dynamically host virtual servers by using the mod_vhost_alias module you read about in the preceding section of the chapter. The module is primarily intended for ISPs and similar large sites that host a large number of virtual sites. This module is for more advanced users and, as such, it is outside the scope of this introductory chapter. Instead, this section concentrates on the traditional ways of hosting virtual servers.

Address-Based Virtual Hosts

After you've configured your Linux machine with multiple IP addresses, setting up Apache to serve them as different websites is simple. You need only put a VirtualHost directive in your httpd.conf file for each of the addresses you want to make an independent website:

 <VirtualHost 212.85.67.67> ServerName gnulix.org DocumentRoot /home/virtual/gnulix/public_html TransferLog /home/virtual/gnulix/logs/access_log ErrorLog /home/virtual/gnulix/logs/error_log </VirtualHost> 

Use the IP address, rather than the hostname, in the VirtualHost tag.

You can specify any configuration directives within the <VirtualHost> tags. For example, you might want to set AllowOverrides directives differently for virtual hosts than you do for your main server. Any directives that aren't specified default to the settings for the main server.

Name-Based Virtual Hosts

Name-based virtual hosts enable you to run more than one host on the same IP address. You must add the names to your DNS as CNAMEs of the machine in question. When an

HTTP client (web browser) requests a document from your server, it sends with the request a variable indicating the server name from which it's requesting the document. Based on this variable, the server determines from which of the virtual hosts it should serve content.

NOTE

Some older browsers are unable to see name-based virtual hosts because this is a feature of HTTP 1.1 and the older browsers are strictly HTTP 1.0 compliant. However, many other older browsers are partially HTTP 1.1 compliant, and this is one of the parts of HTTP 1.1 that most browsers have supported for a while.


Name-based virtual hosts require just one step more than IP address-based virtual hosts. You must first indicate which IP address has the multiple DNS names on it. This is done with the NameVirtualHost directive:

 NameVirtualHost 212.85.67.67 

You must then have a section for each name on that address, setting the configuration for that name. As with IP-based virtual hosts, you need to set only those configurations that must be different for the host. You must set the ServerName directive because it's the only thing that distinguishes one host from another:

 <VirtualHost 212.85.67.67> ServerName bugserver.gnulix.org ServerAlias bugserver DocumentRoot /home/bugserver/htdocs ScriptAlias /home/bugserver/cgi-bin TransferLog /home/bugserver/logs/access_log </VirtualHost> <VirtualHost 212.85.67.67> ServerName pts.gnulix.org ServerAlias pts DocumentRoot /home/pts/htdocs ScriptAlias /home/pts/cgi-bin TransferLog /home/pts/logs/access_log ErrorLog /home/pts/logs/error_log </VirtualHost> 

TIP

If you're hosting websites on an intranet or internal network, users will likely use the shortened name of the machine rather than the FQDN. For example, users might type http://bugserver/index.html in their browser location field rather than http://bugserver.gnulix.org/index.html. In that case, Apache would not recognize that those two addresses should go to the same virtual host. You could get around this by setting up VirtualHost directives for both bugserver and bugserver.gnulix.org, but the easy way around it is to use the ServerAlias directive, which lists all valid aliases for the machine:

 ServerAlias bugserver 


For more information about VirtualHost, refer to the help system on http://localhost/_manual.

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    Red Hat Fedora 4 Unleashed
    Red Hat Fedora 4 Unleashed
    ISBN: 0672327929
    EAN: 2147483647
    Year: 2006
    Pages: 361

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