Updating/Installing mcrypt
If you have php-mcrypt for PHP 5.1.x installed you’ll want to remove it:
Note: Your version number maybe different. Alter below command accordingly.

rpm -e php-mcrypt-5.1.6-15.el5.centos.1

Download php-mcrypt for PHP 5.2.x and install it. You can find a 32-bit php-mcrypt package here FedoraJunkies.
Note: You’ll notice the --nodeps flag in the example. When you try to install php-mcrypt without it you get an error that php-common-5.2.6-2.el5s2 is missing even though it is installed.

wget -c http://sourcemirrors.org/scotth/centos/5/php/php-mcrypt-5.2.6-2.i386.rpm
rpm -i --nodeps php-mcrypt-5.2.6-2.i386.rpm

Restart Apache and you should now see mcrypt information on your testing.php page.

System installs library and creates /usr/lib/php5/../mcrypt.so
Check if mcrypt.ini file exists or create it in /etc/php5/conf.d and added this one liner:


Reference: wiki.centos.org, php.net