Debian官方源因为墙的问题导致下载速度很慢，所以需要更换为国内的源。

一般情况下，将 /etc/apt/sources.list 文件中 Debian 默认的源地址 security.debian.org替换为国内的源地址即可，更换完源请执行apt update

方法一、使用sed命令

sed -i 's|security.debian.org|mirrors.aliyun.com|g' /etc/apt/sources.list

方法二、直接编辑

使用nano或者vi直接编辑sources.list文件后保存即可。

以下是一些国内常用源：

1、163

deb http://mirrors.163.com/debian/ bullseye main
deb-src http://mirrors.163.com/debian/ bullseye main
deb http://mirrors.163.com/debian-security/ bullseye-security main
deb-src http://mirrors.163.com/debian-security/ bullseye-security main
deb http://mirrors.163.com/debian/ bullseye-updates main
deb-src http://mirrors.163.com/debian/ bullseye-updates main

2、阿里云

deb http://mirrors.aliyun.com/debian/ bullseye main
deb-src http://mirrors.aliyun.com/debian/ bullseye main
deb http://mirrors.aliyun.com/debian-security/ bullseye-security main
deb-src http://mirrors.aliyun.com/debian-security/ bullseye-security main
deb http://mirrors.aliyun.com/debian/ bullseye-updates main
deb-src http://mirrors.aliyun.com/debian/ bullseye-updates main

3、华为云

deb http://mirrors.huaweicloud.com/debian/ bullseye main
deb-src http://mirrors.huaweicloud.com/debian/ bullseye main
deb http://mirrors.huaweicloud.com/debian-security/ bullseye-security main
deb-src http://mirrors.huaweicloud.com/debian-security/ bullseye-security main
deb http://mirrors.huaweicloud.com/debian/ bullseye-updates main
deb-src http://mirrors.huaweicloud.com/debian/ bullseye-updates main

4、中科大

deb https://mirrors.ustc.edu.cn/debian/ bullseye main
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye main
deb https://mirrors.ustc.edu.cn/debian-security/ bullseye-security main
deb-src https://mirrors.ustc.edu.cn/debian-security/ bullseye-security main
deb https://mirrors.ustc.edu.cn/debian/ bullseye-updates main
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye-updates main

注意：使用 HTTPS 可以有效避免国内运营商的缓存劫持，需要安装 apt-transport-https，到但是Debian Buster（Debian 10）及以上版本不需要。