Apache IP-based Virtual Host Support
IP-based virtual hosting is a method to apply different directives based on the IP address and port a request is received on. Most commonly, this is used to serve different websites on different ports or interfaces.
As the term IP-based indicates, the server must have a different IP address/port combination for each IP-based virtual host. 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), and/or using multiple port numbers.
In the terminology of Apache HTTP Server, using a single IP address but multiple TCP ports, is also IP-based virtual hosting.
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
Use multiple daemons when:
- 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
- You can afford the memory and file descriptor
requirements of listening to every IP alias on the
machine. It's only possible to
Listento 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
httpdcould listen to N-1 of the addresses, and another could listen to the remaining address.)
Use a single daemon when:
- Sharing of the httpd configuration between virtual hosts is acceptable.
- The machine services a large number of requests, and so the performance loss in running separate daemons may be significant.
Create a separate
httpd installation for each
virtual host. For each installation, use the
Listen directive in the
configuration file to select which IP address (or virtual host)
that daemon services. e.g.
It is recommended that you use an IP address instead of a hostname (see DNS caveats).
For this case, a single
httpd will service
requests for the main server and all the virtual hosts. The
in the configuration file is used to set the values of
configuration directives to different values for each virtual
<VirtualHost 172.20.30.40:80> ServerAdmin [email protected] DocumentRoot "/www/vhosts/www1" ServerName www1.example.com ErrorLog "/www/logs/www1/error_log" CustomLog "/www/logs/www1/access_log" combined </VirtualHost> <VirtualHost 172.20.30.50:80> ServerAdmin [email protected] DocumentRoot "/www/vhosts/www2" ServerName www2.example.org ErrorLog "/www/logs/www2/error_log" CustomLog "/www/logs/www2/access_log" combined </VirtualHost>
It is recommended that you use an IP address instead of a hostname in the <VirtualHost> directive (see DNS caveats).
Specific IP addresses or ports have precedence over their wildcard equivalents, and any virtual host that matches has precedence over the servers base configuration.
Almost any 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 Context using the directive index.
SECURITY: 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 security tips document for details.