debian9可用的apt源

 deb http://archive.debian.org/debian/ stretch main contrib non-free
 deb http://archive.debian.org/debian/ stretch-backports main contrib non-free
 ​
 #deb http://archive.debian.org/debian-security/ stretch/updates main contrib non-free
 #deb-src http://archive.debian.org/debian/ stretch main contrib non-free
 #deb-src http://archive.debian.org/debian-security/ stretch/updates main contrib non-free

参考资料 https://luotianyi.vc/7428.html

以下的不一定可以用！

 官方（海外）：http://archive.debian.org/
 腾讯云：http://mirrors.cloud.tencent.com/debian-archive/
 南京大学：https://mirror.nju.edu.cn/debian-archive/
 软件所：https://mirror.iscas.ac.cn/debian-archive/
 网易163：http://mirrors.163.com/debian-archive/
 阿里云：http://mirrors.aliyun.com/debian-archive/