1. touch  ~/.ssh/authorized_keys
    2. ssh-keygen -t rsa
    3. cat ~/.ssh/id_rsa.pub > ~/.ssh/authorized_keys
    4. chmod 600 ~/.ssh/id_rsa
    5. chmod 700 ~/.ssh/
    8. vim /etc/ssh/sshd_config 
    9. RSAAuthentication yes
    10. PubkeyAuthentication yes              #key登录方式
    11. PermitRootLogin yes
    12. PasswordAuthentication yes           #密码登录方式
    14. systemctl restart sshd