1、先备份
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
【有些新的服务器可能都没有sudo，若无那就跳过吧！】
2、修改更新源
vi /etc/apt/sources.list
把下面的列表任选一个源添加sources.list文件里
163源：
deb http://mirrors.163.com/debian/ jessie main non-free contrib
deb http://mirrors.163.com/debian/ jessie-updates main non-free contrib
deb http://mirrors.163.com/debian/ jessie-backports main non-free contrib
deb-src http://mirrors.163.com/debian/ jessie main non-free contrib
deb-src http://mirrors.163.com/debian/ jessie-updates main non-free contrib
deb-src http://mirrors.163.com/debian/ jessie-backports main non-free contrib
deb http://mirrors.163.com/debian-security/ jessie/updates main non-free contrib
deb-src http://mirrors.163.com/debian-security/ jessie/updates main non-free contrib
阿里云源：
deb http://mirrors.aliyun.com/debian/ jessie main non-free contrib
deb http://mirrors.aliyun.com/debian/ jessie-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ jessie-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ jessie main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ jessie-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ jessie-backports main non-free contrib
deb http://mirrors.aliyun.com/debian-security/ jessie/updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian-security/ jessie/updates main non-free contrib
deb http://mirrors.aliyun.com/debian wheezy main contrib non-free
deb-src http://mirrors.aliyun.com/debian wheezy main contrib non-free
deb http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free
deb http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free
官方源：
deb http://ftp.us.debian.org/debian/ wheezy main
deb-src http://ftp.us.debian.org/debian/ wheezy main
deb http://security.debian.org/ wheezy/updates main
deb-src http://security.debian.org/ wheezy/updates main
deb http://ftp.us.debian.org/debian/ wheezy-updates main
deb-src http://ftp.us.debian.org/debian/ wheezy-updates main
香港源：
deb http://ftp.hk.debian.org/debian/ jessie main
deb-src http://ftp.hk.debian.org/debian/ jessie main
deb http://security.debian.org/ jessie/updates main
deb-src http://security.debian.org/ jessie/updates main
# jessie-updates, previously known as 'volatile'
deb http://ftp.hk.debian.org/debian/ jessie-updates main
deb-src http://ftp.hk.debian.org/debian/ jessie-updates main
更新源
apt-get update
更新软件
apt-get upgrade