Install PHP Mcrypt extension on RHEL 6

The php-mcrypt extension is not available on Redhat Enterprise Linux 6 although some applications such as Magento or phpMyAdmin require it to work properly.
We can easily install it though from the Fedora Project repositories.
1. Download the following RPM pacakges:

# wget http://dl.fedoraproject.org/pub/epel/6/x86_64/php-mcrypt-5.3.3-1.el6.x86_64.rpm
# wget http://dl.fedoraproject.org/pub/epel/6/x86_64/libmcrypt-2.5.8-9.el6.x86_64.rpm

2. Install them using YUM:

yum localinstall php-mcrypt-5.3.3-1.el6.x86_64.rpm libmcrypt-2.5.8-9.el6.x86_64.rpm

3. Reload Apache server to load the extension up:

# service httpd restart

Source: http://injustfiveminutes.wordpress.com/2012/11/23/install-php-mcrypt-extension-on-rhel-6/