debian9源修改如下：
deb http://mirrors.aliyun.com/debian/ stretch main non-free contrib
deb http://mirrors.aliyun.com/debian/ stretch-proposed-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ stretch-proposed-updates main non-free contrib
deb http://mirrors.aliyun.com/debian-security/ stretch/updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian-security/ stretch/updates main non-free contrib
deb http://http.us.debian.org/debian/ stretch main contrib non-free
deb http://security.debian.org/ stretch/updates main contrib non-free
更新源并升级
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
有不对之处请大神指点