无论我们在国内还是国外服务商购买的云服务器，拿到手需要做的事情就是检查硬盘有没有挂载，同时需要update检查源升级最新软件包。这里我们经常有使用的主机商镜像都是比较老的或者是原生态的，镜像源都比较陈旧或者更新出现错误，于是我们会去修改国内的镜像源。
在”Ubuntu18.04更换阿里云镜像源文件解决系统无法升级问题”前几天的文章中也有将一台服务器换成阿里云Ubuntu镜像源的。今天有遇到Debian9需要修改镜像源的，于是找到网上一些可用的源，如果我们以后有需要用到的时候可以选择更换。
/etc/apt/sources.list
源地址在系统这个位置，我们可以将原来的系统自带的备份一份，然后再修改下面一些可选择的。
阿里云镜像：
deb http://mirrors.aliyun.com/debian/ stretch main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch main non-free contrib
deb http://mirrors.aliyun.com/debian-security stretch/updates main
deb-src http://mirrors.aliyun.com/debian-security stretch/updates main
deb http://mirrors.aliyun.com/debian/ stretch-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ stretch-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch-backports main non-free contrib
华为云镜像：
deb https://mirrors.huaweicloud.com/debian/ stretch main contrib non-free
deb-src https://mirrors.huaweicloud.com/debian/ stretch main contrib non-free
deb https://mirrors.huaweicloud.com/debian/ stretch-updates main contrib non-free
deb-src https://mirrors.huaweicloud.com/debian/ stretch-updates main contrib non-free
deb https://mirrors.huaweicloud.com/debian/ stretch-backports main contrib non-free
deb-src https://mirrors.huaweicloud.com/debian/ stretch-backports main contrib non-free
160镜像：
deb http://mirrors.163.com/debian/ stretch main non-free contrib
deb http://mirrors.163.com/debian/ stretch-updates main non-free contrib
deb http://mirrors.163.com/debian/ stretch-backports main non-free contrib
deb-src http://mirrors.163.com/debian/ stretch main non-free contrib
deb-src http://mirrors.163.com/debian/ stretch-updates main non-free contrib
deb-src http://mirrors.163.com/debian/ stretch-backports main non-free contrib
deb http://mirrors.163.com/debian-security/ stretch/updates main non-free contrib
deb-src http://mirrors.163.com/debian-security/ stretch/updates main non-free contrib
上交大镜像：
deb https://mirror.sjtu.edu.cn/debian/ stretch main contrib non-free
deb-src https://mirror.sjtu.edu.cn/debian/ stretch main contrib non-free
deb https://mirror.sjtu.edu.cn/debian/ stretch-updates main contrib non-free
deb-src https://mirror.sjtu.edu.cn/debian/ stretch-updates main contrib non-free
deb https://mirror.sjtu.edu.cn/debian/ stretch-backports main contrib non-free
deb-src https://mirror.sjtu.edu.cn/debian/ stretch-backports main contrib non-free
deb https://mirror.sjtu.edu.cn/debian-security/ stretch/updates main contrib non-free
deb-src https://mirror.sjtu.edu.cn/debian-security/ stretch/updates main contrib non-free
中科大镜像：
deb https://mirrors.ustc.edu.cn/debian/ stretch main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ stretch main contrib non-free
deb https://mirrors.ustc.edu.cn/debian/ stretch-updates main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ stretch-updates main contrib non-free
deb https://mirrors.ustc.edu.cn/debian/ stretch-backports main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ stretch-backports main contrib non-free
deb https://mirrors.ustc.edu.cn/debian-security/ stretch/updates main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian-security/ stretch/updates main contrib non-free
更换源之后，我们执行脚本：
apt-get update -y
更新如果没有报错那就说明源没有问题，如果有报错我们可以更换直到没有问题的。
