EPEL：企业版 Linux 附加软件包，即 Extra Packages for Enterprise Linux

一、官方安装教程

RHEL/CentOS 6:
yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm
RHEL/CentOS 7:
yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

二、配置 EPEL 阿里源

1、备份(如有配置其他epel源)

mv /etc/yum.repos.d/epel.repo /etc/yum.repos.d/epel.repo.backup
mv /etc/yum.repos.d/epel-testing.repo /etc/yum.repos.d/epel-testing.repo.backup

2、下载新repo 到/etc/yum.repos.d/

epel(RHEL 7)
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

epel(RHEL 6)
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo

epel(RHEL 5)
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-5.repo

参考链接：
EPEL 官方地址：http://fedoraproject.org/wiki/EPEL
阿里巴巴开源镜像站：https://opsx.alibaba.com/mirror