说明：
Ubuntu默认安装下没有配置国内apt-get源、这样使用apt-get在线安装软件会很慢，下面教大家配置apt-get国内镜像源，在线安装SSH服务（最小话安装的Ubuntu默认没有安装SSH）
1、配置apt-get源
cp /etc/apt/sources.list /etc/apt/sources.listbak #备份原有配置文件
nano /etc/apt/sources.list #编辑，添加以下代码：
deb http://mirrors.163.com/ubuntu/ oneiric main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ oneiric-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ oneiric-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ oneiric-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ oneiric-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ oneiric main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ oneiric-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ oneiric-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ oneiric-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ oneiric-backports main restricted universe multiverse
ctrl+o #保存配置
ctrl+x #退出
apt-get update #更新系统
apt-get upgrade #更新软件包
2、安装SSH服务
apt-get install ssh #安装ssh服务
