问题一：配置ssh免密登录时出现错误
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /home/g/.ssh/id_dsa
debug3: no such identity: /home/g/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/g/.ssh/id_ecdsa
debug3: no such identity: /home/g/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/g/.ssh/id_ed25519
debug3: no such identity: /home/g/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
解决方式：修改vim /etc/ssh/sshd_config配置中，StrictModes no，然后重启ssh:service sshd restart,就可以免密登录了
如果StrictModes为yes必需保证存放公钥的文件夹的拥有与登陆用户名是相同的。
问题二：ssh的时候出现
当ssh root@10.4.8.15出现如下错误：
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:AmePGXvg0Y7uHo//Gpc2VnOFl4h2XLRmqHvSWCYNxh4.
Please contact your system administrator.
Add correct host key in /home/g/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/g/.ssh/known_hosts:16
remove with:
ssh-keygen -f "/home/g/.ssh/known_hosts" -R 10.4.8.15
ECDSA host key for 10.4.8.15 has changed and you have requested strict checking.
Host key verification failed.
则说明，对应机器的公钥改变了，验证错误。
解决方式,删除对应的公钥信息：shh-keygen -R 10.4.8.15
