Visit your web server in Firefox. Activate Firebug by clicking the Firebug icon on the top right side.

If you check the HTTP response headers in Firebug, it will show the Apache version along with your operating system name and version.

To hide this information from browsers, you will need to make some changes in Apache's main configuration file.

You can do this by editing the httpd.conf file:

sudo vi /etc/apache/apache2.conf

Add the following line at the end of file:

/etc/apache/apache2.conf

ServerSignature Off
ServerTokens Prod

Save the file and restart the Apache service to reflect these changes:

sudo apachectl restart

Now, open Firefox and access your web server. Check the HTTP response headers in Firebug, You should see that setting ServerSignature to Off has removed the version information from Server.