主机HostKey值改变导致SSH连接报出警告

问题描述：
当使用SSH连接主机时，会在本地的"known_hosts"文件中，增加一条保存所连主机HostKey值的记录，该记录的主键可以是所连主机的域名，也可以是所连主机的IP地址。

当主机的HostKey值改变了，会给出类似如下警告：

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 RSA key sent by the remote host is
a3:8f:7c:07:c9:12:d8:aa:cd:c2:ba:b3:27:68:bc:c2.
Please contact your system administrator.
Add correct host key in /home/dsl/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/dsl/.ssh/known_hosts:8
RSA host key for xxx.xxx.xxx.xxx has changed and you have requested strict checking.
Host key verification failed.

当主机域名和IP地址对应的两个HostKey值不一致时，会给出类似如下警告：

Warning: the ECDSA host key for '[hostname]:port' differs from the key for the IP address '[ipaddress]:port'
Offending key for IP in /home/dsl/.ssh/known_hosts:5
Matching host key in /home/dsl/.ssh/known_hosts:147

解决方案：

删除掉旧的HostKey值记录，下次重新保存新的就行。

具体命令：使用VIM编辑器找到相应行，删除就行了！

备注：理论上来说，"ssh-keygen -R hostname|ip"命令也可以达到目标，但是我试了几次，都失败了，不知道怎么回事。