安装epel地址：

centos6 32位    http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
            64位    http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
centos7    http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-8.noarch.rpm

epel 安装地址