服务器运行
ssh-keygen -t rsa
ls -l ~/.ssh/
id_rsa 私钥
id_rsa.pub 公钥
拷贝id_rsa到本地报错修改权限
Permissions 0644
for 'id_rsa' are too open.
chmod 400 id_rsa
成功登陆
ssh -i id_rsa -p 端口 -l root ip地址
参考：
SSH 使用密钥登录并禁止口令登录实践SSH Key: “Permissions 0644 for ‘id_rsa.pub’ are too open.” on mac
