一：在 /etc/apt/目录下建立 apt.conf 文件增加如下
Acquire::http::Proxy "http://proxyxxxxxxx:port";
注意格式：最后用;结束
保存
执行
sudo apt-get update
ok .........
二：
附debian10的 163源
deb http://mirrors.163.com/debian/ buster main non-free contrib
deb http://mirrors.163.com/debian/ buster-updates main non-free contrib
deb http://mirrors.163.com/debian/ buster-backports main non-free contrib
deb-src http://mirrors.163.com/debian/ buster main non-free contrib
deb-src http://mirrors.163.com/debian/ buster-updates main non-free contrib
deb-src http://mirrors.163.com/debian/ buster-backports main non-free contrib