在debian圖形化安裝過程中就可以選擇網絡鏡像的位置
據說電信用清華的源快，移動的用網易源快
備份源配置文件：
cp /etc/apt/sources.list /etc/apt/sources.listbak
sudo nano /etc/apt/sources.list
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
更新源：
apt-get update