更新 known_host 内容
当你使用ssh用户端登入IP或网域名称，发生如下的警告而无法登入：
[danny@lab-p5e-vm ~]$ ssh root@192.168.9.86 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ 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:ifadanbrGuSaIBz00KO8GvU2FyxvCBNLtSpjL+pngxs. Please contact your system administrator. Add correct host key in /home/danny/.ssh/known_hosts to get rid of this message. Offending ECDSA key in /home/danny/.ssh/known_hosts:22 ECDSA host key for 192.168.9.86 has changed and you have requested strict checking. Host key verification failed. [danny@lab-p5e-vm ~]$
这主要的原因为与ssh server连接的公钥指纹码已经变更，与储存公钥指纹码的known_hosts内容不同而无法登入，
那要如何才能登入？首先你要先用指令将已储存该网域/IP的公钥指纹码移除：
ssh-keygen -R 192.168.9.86
之后再重新登入就会再询问你要不要储存新的公钥指纹码：
[danny@lab-p5e-vm ~]$ ssh root@192.168.9.86 The authenticity of host '192.168.9.86 (192.168.9.86)' can't be established. ECDSA key fingerprint is SHA256:ifadanbrGuSaIBz00KO8GvU2FyxvCBNLtSpjL+pngxs. Are you sure you want to continue connecting (yes/no)?
此时再按下yes就会将新的公钥指纹码储存后更新，再输入登入密码就完成登入。
参考资料
关键字：REMOTE HOST IDENTIFICATION HAS CHANGED