使用SecureCRT 与虚拟机进行通信，提示The remote system refused the connection
解决：由于缺少SSH服务器端
sudo apt-get install openssh-server
启动、停止和重启openssh-server的命令如下
/etc/init.d/ssh start
/etc/init.d/ssh stop
/etc/init.d/ssh restart
使用SecureCRT 与虚拟机进行通信，提示The remote system refused the connection
sudo apt-get install openssh-server
启动、停止和重启openssh-server的命令如下
/etc/init.d/ssh start
/etc/init.d/ssh stop
/etc/init.d/ssh restart