Precisa utilizar o repositório EPEL em seu servidor CentOS?
Veja abaixo como fazer a instalação dele:

On RHEL/CentOS – 32-bit OS

# -------------- For RHEL/CentOS 6 -------------- #
wget http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
rpm -ihv epel-release-6-8.noarch.rpm


# -------------- For RHEL/CentOS 5 -------------- #
wget http://download.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm
rpm -ihv epel-release-5-4.noarch.rpm

On RHEL/CentOS – 64-bit OS

# -------------- For RHEL/CentOS 7 -------------- #
wget dl.fedoraproject.org/pub/epel/7/x86_64/Packages/e/epel-release-7-11.noarch.rpm
rpm -ihv epel-release-7-11.noarch.rpm 

# -------------- For RHEL/CentOS 6 -------------- #
wget http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -ihv epel-release-6-8.noarch.rpm