#1、生成密钥
ssh-keygen -t rsa
#2、使用以下命令将公钥导入到VPS：
cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys
#3、修改SSH的配置文件/etc/ssh/sshd_config :
vi /etc/ssh/sshd_config
:%s/#RSAAuthentication yes/RSAAuthentication yes/g
:%s/#PubkeyAuthentication yes/PubkeyAuthentication yes/g
:%s/#AuthorizedKeysFile/AuthorizedKeysFile/g
 
#禁止密码登录（可选）：
:%s/PasswordAuthentication yes/PasswordAuthentication no/g
 
#保存后重启
service sshd restart

vi /etc/ssh/sshd_config
:s/#ClientAliveCountMax 3/ClientAliveCountMax 86400/g  
/etc/rc.d/init.d/sshd restart
echo "export TMOUT=1000000" >> .bash_profile