Apache- Virtual hosts configuration

VirtualHost
and tags create a container outlining the characteristics of a virtual host.

The container accepts most configuration directives.A set of commented

VirtualHost container is provided in httpd.conf, which illustrates the

minimum set of configuration directives necessary for each virtual host.

Setting Up Virtual Hosts
To create a name-based virtual host, it is best use the virtual host

container provided in httpd.conf as an example.
The virtual host example read as follows:

#NameVirtualHost *
#
#
# ServerAdmin webmaster@dummy-host.example.com
# DocumentRoot /www/docs/dummy-host.example.com
# ServerName dummy-host.example.com
# ErrorLog logs/dummy-host.example.com-error_log
# CustomLog logs/dummy-host.example.com-access_log common
#

To activate name-based virtual hosting, uncomment the NameVirtualHost

line by removing the hash mark (#) and replace the asterisk (*) with the

IP address assigned to the machine.
Next, configure a virtual host, by uncommenting and customizing the container.
On the line, change the asterisk (*) to the server’s IP address.

Change the ServerName to a valid DNS name assigned to the machine,

and configure the other directives as necessary.
The container is highly customizable and accepts almost every

directive available within the main server configuration.

Tip :If configuring a virtual host to listen on a non-default port, that port must be added to the Listen directive in the global settings section of the /etc/httpd/conf/httpd.conf file.
To activate a newly created virtual host the Apache HTTP Server must be reloaded or restarted.

The Secure Web Server Virtual Host
By default, the Apache HTTP Server is configured as both a non-secure and a secure server. Both the non-secure and secure servers use the same IP address and host name, but listen on different ports: 80 and 443 respectively. This

enables both non-secure and secure communications to take place simultaneously.One aspect of SSL enhanced HTTP transmissions are that they are more resource intensive than the standard HTTP protocol, so a secure server cannot serve as many pages per second. For this reason it is often a good idea to minimize the information available from the secure server, especially on a high traffic Web site.

The configuration directives for the secure server are contained within virtual host tags in the /etc/httpd/conf.d/ssl.conf file.

By default, both the secure and the non-secure Web servers share the same DocumentRoot. It is recommended that the DocumentRoot be different for the Secure Web servers.
To stop the non-secure Web server from accepting connection comment the line in httpd.conf which reads Listen 80 by placing a hash mark at the beginning of the line. When finished it will look like the following example:#Listen 80

Default Modules
The Apache HTTP Server is distributed with a number of modules. By default the following modules are installed and enabled with the httpd package on Red Hat Linux:

mod_access
mod_auth
mod_auth_anon
mod_auth_dbm
mod_auth_digest
mod_include
mod_log_config
mod_env
mod_mime_magic
mod_cern_meta
mod_expires
mod_headers
mod_usertrack
mod_unique_id
mod_setenvif
mod_mime
mod_dav
mod_status
mod_autoindex
mod_asismod_info
mod_cgimod_dav_fs
mod_vhost_alias
mod_negotiation
mod_dirmod_imap
mod_actions
mod_speling
mod_userdir
mod_alias
mod_rewrite
mod_proxy
mod_proxy_ftp
mod_proxy_http
mod_proxy_connect

Additionally, the following modules are available by installing additional packages:

mod_auth_mysql
mod_auth_pgsql
mod_perl
mod_python
mod_ssl
php
squirrelmail

Adding Modules
The Apache HTTP Server supports Dynamically Shared Objects (DSOs) or modules, which can easily be loaded at runtime as necessary.

For the Apache HTTP Server to use a DSO, it must be specified in a LoadModule directive within in /etc/httpd/conf/httpd.conf; if the module is provided by a separate package, the line must appear within the modules configuration file in the /etc/httpd/conf.d/ directory.If adding or deleting modules from http.conf, Apache HTTP Server must be reloaded or restarted.If creating a new module, first install the httpd-devel package as it contains the include files, the header files, as well as the APache eXtenSion (/usr/sbin/apxs) application, which uses the include files and the header files to compile DSOs.After writing a module, use /usr/sbin/apxs to compile the module sources outside the Apache source tree. Once compiled, put the module in the /usr/lib/httpd/ directory. Then add a LoadModule line to the httpd.conf,

using the following structure:
LoadModule