1. mv /etc/yum.repos.d/CentOS-Base.repo CentOS-Base.repo.bak
  2. wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
  3. wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
  4. yum install epel-release
  5. yum clean all
  6. yum makecache