CentOS 官方下载地址：
https://www.centos.org/download/
Centos国内下载源
http://mirrors.sohu.com/centos/7/isos/x86_64/
http://mirrors.aliyun.com/centos/7/isos/x86_64/
http://man.linuxde.net/download/CentOS
http://mirrors.btte.net/centos/7/isos/x86_64/
http://mirrors.cn99.com/centos/7/isos/x86_64/
http://centos.ustc.edu.cn/centos/7/isos/x86_64/
http://mirrors.neusoft.edu.cn/centos/7/isos/x86_64/
http://mirror.lzu.edu.cn/centos/7/isos/x86_64/
http://mirrors.163.com/centos/7/isos/x86_64/
http://ftp.sjtu.edu.cn/centos/7/isos/x86_64/
