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Installing And Configuring Apache On Linux

Apache is the most popular and preferred Web servers on the Linux platform. Also, its one of oldest Web server developed especially for Linux. What makes Apache so popular? Firstly, it's free—an excellent by-product of the open source movement. Secondly, even though it's free, its matches any other commercially sold Web server in terms of comprehensive documentation or direct technical support. In fact, Apache is well-documented and supported open source freeware that exist today. Not to forget the fact that it is available on almost all platforms, starting from AUX, Solaris, Linux to UnixWare (and even Windows NT). This coupled with the ease of installation, small download size (of about 2.9 MB) and availability of source code makes it the most preferred Web server.

Here we shall first take you through installing Apache from its packaged or precompiled form, then work on few scripts that will help you to start, reboot, restart the server, get under the skin and learn about the three ".conf" files that form the heart of Apache, and finally go a bit deeper by doing virtual hosting.

Installation Basics
Apache can be downloaded at http://www.apache.org (its also bundled along with Caldera eServer 2.3.1 available on the Network Magazine CD). Download it to a directory of your choice (/tmp in this case). After that, you can install it in one of the default locations by the commands listed below:

mkdir /etc/httpd
cd /etc/httpd
mv /tmp/apache_1.3.19.tar.gz /etc/httpd
tar -zxvf apache_1.3.19.tar.gz && cd /etc/httpd/apache_1.3.19 && ./configure --prefix=/etc/httpd && make && make install

This untars the Apache file and configures it in accordance with the distribution or platform that you are using.

These commands will install the Apache server in /etc/httpd directory
Note: I have made some changes over here. Basic reason being, once we untar (unzip) the file, we need to configure it in accordance with the kernel version and distribution that we are using. Since each distribution follows a specific installation procedure, the commands listed below are general commands that work for every distribution that exists.

.conf: Next Steps

Once the installation is complete, the files can be viewed via /etc/httpd directory.

Go to the /conf directory and make sure that the following files are present: httpd.conf, access.conf and srm.conf. Some versions of Apache use the httpd.conf-distro as the name to avoid conflicts. In such cases rename the files with a .conf extension.

Make a list of the domain name, the IP address and the different directories that the server shall point to. Over here we are making use of an IP named 127.0.0.1 and domain name as bahbah.com. Edit the /etc/hosts file and make the following entry in it:

127.0.0.1 bahbah bahbah.com

This line resolves the hostname for the server. You can test it by typing "ping 127.0.0.1"

Now change to /etc/httpd directory and edit the httpd.conf file. This file forms the heart of Apache server. Though there are comments included in the file itself, don't make any changes unless you are sure what you are up to. Listed below are some changes that are necessary to get the server working.

Changing The httpd.conf File

The first 50 odd lines shall have a list of the various modules. Modules are small programs that help to build up a fully functional server. Ranging from Custom 404 Error Messages to SSI directives, one can configure them as per requirement and even add their own modules if desired.

Going further down the file, one encounters the following text statements:

ServerType standalone

Port 80

Keep the above settings as they are.

HostnameLookups on

This line resolves the IP address of the person to the domain from which he/she is visiting. It adds itself to the "logs" file and proves useful if you want to keep a track of your visitors.

User nobody

Group nobody

One can add the Group/User name or number who will be starting the httpd server.

ServerAdmin notice@bahbah.com

If anything goes wrong then an email is sent to the address specified above.

ServerRoot /etc/httpd

Points to the location where the configuration, error and log files for Apache are kept.

BindAddress *

Planning to use Virtual Hosts, then this option serves variety of tasks. Though it can be set to a particular domain name or IP, giving it a wild card just eases the task if you plan to setup multiple hosts.

The remaining things are self-explanatory and should not be changed. Changes should only be made once you encounter the statement shown below.

ServerName bahbah.com

NameVirtualHost 127.0.0.1

Make sure that you are having a valid DNS name for your host.

Other settings for StartServers, MaxClients should be kept at their default values. These values are optimised for a general server and making them too high or low shall affect performance drastically.

Changing The access.conf File

Modify the following lines access.conf file:

AllowOverride None

order allow,deny

allow from all

AllowOverride None

Options ExecCGI

</Directory>

This points to the default html and cgi file storage location. If you are using your server to host just one site, put all your html/cgi files in the location mentioned above. You can even change it to another location.

Changing The srm.conf File

All external applications like Real Player, redirects, various MIME types, language supports, programming languages like PHP are handled by this file. It is best not to change its default values. Just read it once to understand its functioning but don't modify the file till you are comfortable with Apache.

The above sections complete the configuration of Apache server. You now needs to restart the server so that the changes can take effect. The configuration file for the same purpose is given below. Store it in your /etc/rc.d/init.d directory.

Simply type "./httpd restart" and your server shall restart with a OK status. On encountering any error the server shall stop and give you the error and possibly the line number.

Once the server is restarted you can check it by calling it by its IP address or its own name.

lynx www.bahbah.com or lynx 127.0.0.1 should fetch you the default Apache start up page. If you have put some other file in the /home/httpd/html directory then that file shall be shown.

Nothing's happening? Try "ping 127.0.0.1" and it should give a successful status reply. If it's not then probably you have not made an entry in /etc/hosts file.

From this moment, your machine is now a full-fledged Web server. Any one who types the IP address or domain name (bahbah.com) in this case shall be connected to your server. You can view the various activities such as the pages viewed, number of unique hits, error messages and other things by having a look at your log files in the corresponding /logs directory.

Source code for httpd file

#!/bin/sh

. /etc/rc.d/init.d/functions

case "$1" in

start)

echo -n "Starting httpd: "

daemon httpd

echo

touch /var/lock/subsys/httpd

;;

stop)

echo -n "Shutting down http: "

killproc httpd

echo

rm -f /var/lock/subsys/httpd

rm -f /var/run/httpd.pid

;;

status)

status httpd

;;

restart)

$0 stop

$0 start

;;

reload)

echo -n "Reloading httpd: "

killproc httpd -HUP

echo

;;

echo "Usuage:$0 {start|stop|restart|status}"

esac

exit 0

Virtual Hosting

Apache server also supports virtual hosting. Virtual hosting allows you to host multiple domains on a single IP. In other words you can use the same IP address to host various domains such as bahbah.com, bah.com, blahblah.com to name a few.

Suppose we plan to virtually host the domains listed above.

For this we have to make changes to the /etc/hosts and the httpd.conf file.

The /etc/hosts file should bear the following look:

127.0.0.1 bahbah bahbah.com

127.0.0.1 bah bah.com

127.0.0.1 blahblah blahblah.com

Add the following listing at the end of httpd.conf file located at the /etc/httpd/conf location

ServerName www.bahbah.com

DocumentRoot /www/bahbah #This points to the location of storage of html and other files corresponding to

bahbah.com.

Errorlog /www/bahbah/errorbahbah.log #Error messages are stored over here.

</VirtualHost>

Restart the server and you can now access two domain names with a single IP.

What we have done over here is configured our server to listen for a specific IP 127.0.0.1.

Say a person enters http://www.bahbah.com in his browser. His machine shall then resolve to a specific IP address and try to connect to 127.0.0.1. On connecting to 127.0.0.1, if it is acting as a dedicated server, it will serve the required files else it will have a look at /etc/hosts file, then at httpd.conf file and display only those files that are relevant to the request.

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Anurag Phadke can be reached at cbca@mantraonline.com