说明：买的阿里云国内学生机，一年114.开通后第一件事当然是重装。装完后发现国外源"snapshot.debian.org"特别慢，遂换成国内的。
VPS一键重装Debian系统

更换步骤

vi /etc/apt/sources.list
加#注释掉原来的，并添加阿里云源地址

deb http://mirrors.aliyun.com/debian stretch main contrib non-free
deb-src http://mirrors.aliyun.com/debian stretch main contrib non-free
deb http://mirrors.aliyun.com/debian stretch-updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian stretch-updates main contrib non-free
deb http://mirrors.aliyun.com/debian-security stretch/updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian-security stretch/updates main contrib non-free

stretch可以替换成jessie或者wheezy
保存后执行
apt-get update

参考：
http://ningxy.cn/Debian%209%20%E6%8D%A2%E9%98%BF%E9%87%8C%E5%8C%85%E6%BA%90.html