前置：
yum install -y yum-priorities
vi /etc/yum.repos.d/CentOS-Base.repo找到[base]，添加 ：
priority=1
rpm -ivh http://mirrors.ustc.edu.cn/fedora/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
vi /etc/yum.repos.d/epel.repo在每一个里面加上
priority=2
rpmforge:
rpm -ivh http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm
vi /etc/yum.repos.d/rpmforge.repo在每一个里面加上
priority=3
rpm -ivh http://download1.rpmfusion.org/free/el/updates/6/x86_64/rpmfusion-free-release-6-1.noarch.rpm
vi /etc/yum.repos.d/rpmfusion-free-updates.repo在每一个里面加上
priority=4
vi /etc/yum.repos.d/rpmfusion-free-updates-testing.repo在每一个里面加上
priority=4
最后：
yum check-update
