1.安装wget
yum install -y wget
2.备份/etc/yum.repos.d/CentOS-Base.repo
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.back
3.下载阿里云的CentOS-6.repo文件
wget -O CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
4.重新加载yum
yum clean all
yum makecache