发现好多vps默认的Debian使用 apt install 安装软件的时候都会报 404 Not Found 的错误，apt update 也不行
应该是 sources.list 里面的源地址问题，以cloudcone的为例，我直接修改成最新的Debian官方源就可以了
一）备份
mv /etc/apt/sources.list /etc/apt/sources.list.old
二）替换（直接一次性复制多行命令粘贴运行就行，或者也可以自己vi更换相关内容）
官方源
cat > /etc/apt/sources.list << EOF
deb https://deb.debian.org/debian/ bullseye main contrib non-free
deb-src https://deb.debian.org/debian/ bullseye main contrib non-free
deb https://deb.debian.org/debian/ bullseye-updates main contrib non-free
deb-src https://deb.debian.org/debian/ bullseye-updates main contrib non-free
deb https://deb.debian.org/debian/ bullseye-backports main contrib non-free
deb-src https://deb.debian.org/debian/ bullseye-backports main contrib non-free
deb https://deb.debian.org/debian-security/ bullseye-security main contrib non-free
deb-src https://deb.debian.org/debian-security/ bullseye-security main contrib non-free
EOF
清华源
cat > /etc/apt/sources.list << EOF
deb https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye main contrib non-free
deb https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-updates main contrib non-free
deb https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-backports main contrib non-free
deb https://mirrors.tuna.tsinghua.edu.cn/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian-security/ bullseye-security main contrib non-free
EOF
中科大源
cat > /etc/apt/sources.list << EOF
deb https://mirrors.ustc.edu.cn/debian/ bullseye main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye main contrib non-free
deb https://mirrors.ustc.edu.cn/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye-updates main contrib non-free
deb https://mirrors.ustc.edu.cn/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye-backports main contrib non-free
deb https://mirrors.ustc.edu.cn/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian-security/ bullseye-security main contrib non-free
EOF
阿里云源（公网）
cat > /etc/apt/sources.list << EOF
deb https://mirrors.aliyun.com/debian/ bullseye main contrib non-free
deb-src https://mirrors.aliyun.com/debian/ bullseye main contrib non-free
deb https://mirrors.aliyun.com/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.aliyun.com/debian/ bullseye-updates main contrib non-free
deb https://mirrors.aliyun.com/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.aliyun.com/debian/ bullseye-backports main contrib non-free
deb https://mirrors.aliyun.com/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.aliyun.com/debian-security/ bullseye-security main contrib non-free
EOF
阿里云内网源（阿里云服务器使用，不消耗公网流量）
cat > /etc/apt/sources.list << EOF
deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye main contrib non-free
deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye-updates main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye-updates main contrib non-free
deb http://mirrors.cloud.aliyuncs.com/debian/ bullseye-backports main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian/ bullseye-backports main contrib non-free
deb http://mirrors.cloud.aliyuncs.com/debian-security/ bullseye-security main contrib non-free
deb-src http://mirrors.cloud.aliyuncs.com/debian-security/ bullseye-security main contrib non-free
EOF
腾讯云源（公网）
cat > /etc/apt/sources.list << EOF
deb https://mirrors.cloud.tencent.com/debian/ bullseye main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian/ bullseye main contrib non-free
deb https://mirrors.cloud.tencent.com/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian/ bullseye-updates main contrib non-free
deb https://mirrors.cloud.tencent.com/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian/ bullseye-backports main contrib non-free
deb https://mirrors.cloud.tencent.com/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian-security/ bullseye-security main contrib non-free
EOF
腾讯云内网源（阿里云服务器使用，不消耗公网流量）
cat > /etc/apt/sources.list << EOF
deb http://mirrors.tencentyun.com/debian/ bullseye main contrib non-free
deb-src http://mirrors.tencentyun.com/debian/ bullseye main contrib non-free
deb http://mirrors.tencentyun.com/debian/ bullseye-updates main contrib non-free
deb-src http://mirrors.tencentyun.com/debian/ bullseye-updates main contrib non-free
deb http://mirrors.tencentyun.com/debian/ bullseye-backports main contrib non-free
deb-src http://mirrors.tencentyun.com/debian/ bullseye-backports main contrib non-free
deb http://mirrors.tencentyun.com/debian-security/ bullseye-security main contrib non-free
deb-src http://mirrors.tencentyun.com/debian-security/ bullseye-security main contrib non-free
EOF
Linode源
cat > /etc/apt/sources.list << EOF
deb http://mirrors.linode.com/debian/ bullseye main contrib non-free
deb-src http://mirrors.linode.com/debian/ bullseye main contrib non-free
deb http://mirrors.linode.com/debian/ bullseye-updates main contrib non-free
deb-src http://mirrors.linode.com/debian/ bullseye-updates main contrib non-free
deb http://mirrors.linode.com/debian/ bullseye-backports main contrib non-free
deb-src http://mirrors.linode.com/debian/ bullseye-backports main contrib non-free
deb http://mirrors.linode.com/debian-security/ bullseye-security main contrib non-free
deb-src http://mirrors.linode.com/debian-security/ bullseye-security main contrib non-free
EOF
三）更新索引
