The EPEL repo is one you should have when you first install Centos or RHEL..
It contains many important extra packeages which are not found in the standard installation.
It can be installed using a standard shell command as below.
yum install epel-release -y
Below are old instructions for installing the EPEL repository RPM. Use this if the above process does not work for you.
CentOS 6 – 32-bit
CentOS 6 – 64-bit
After running the above commands for your relevant CentOS version, the following file is created:
This file can be edited directly to enable or disable the EPEL repo.