YUM源

阿里镜像站：
https://opsx.alibaba.com/

阿里CentOS源：
https://mirrors.aliyun.com/help/centos
阿里epel源：
http://mirrors.aliyun.com/help/epel

操作命令：

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
yum makecache

清华yum仓库
https://mirrors.tuna.tsinghua.edu.cn/