两台服务器之间设置免密互方
两台服务器分别执行
```
ssh-copy-id "-p 22 yansiyu@47.254.17.153"
ssh-copy-id "-p 22 yansiyu@47.254.17.151"
```
输入密码即可
如果提示/usr/bin/ssh-copy-id: ERROR: No identities found
那么`ssh-keygen`
设置为证书登录,这里设置为`no`,那么不允许密码登录。
vim /etc/ssh/sshd_config
`PasswordAuthentication no`