Centos6镜像源

Centos6虽然已经彻底停止维护，但现有的机器也不能放弃啊…

阿里centos-vault

http://mirrors.aliyun.com/centos-vault/

清华图灵centos-vault

https://mirrors.tuna.tsinghua.edu.cn/centos-vault/

阿里epel-archive

http://mirrors.aliyun.com/epel-archive/