fix the error “host key verification failed”

错误信息

在使用 iterms 通过 ssh 连接某服务器时，报了如下提示：

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@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
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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 the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
dd:cf:50:31:7a:78:93:13:dd:99:67:c2:a2:19:22:13.
Please contact your system administrator.
Add correct host key in /home/user01/.ssh/known_hosts to get rid of this message.
Offending key in /home/lcz/.ssh/known_hosts:7
RSA host key for 192.168.21.49 has changed and you have requested strict checking.
Host key verification failed.

修复方式：

1. 手动删除旧的秘钥

# vi ~/.ssh/known_hosts
192.168.1.113 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBLrY91bQOihgFZQ2Ay9KiBG0rg51/YxJAK7dvAIopRaWzFEEis3fQJiYZNLzLgQtlz6pIe2tj9m/Za33W6WirN8=
192.168.19.11 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCrY/m16MdFt/Ym51Cc7kxZW3R2pcHV1jlOclv6sXix1UhMuPdtoboj+b7+NLlTcjfrUccL+1bkg8EblYucymeU=
# 根据提示的IP地址，将该秘钥删除
192.168.21.49 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCrY/m16MdFt/Ym51Cc7kxZW3R2pcHV1jlOclv6sXix1UhMuPdtoboj+b7+NLlTcjfrUccL+1bkg8EblYucymeU=

2. 使用 ssh-keygen 目录删除旧秘钥

$ ssh-keygen -R [hostname | IP address]

$ ssh-keygen -R 192.168.21.49
# Host 192.168.21.49 found: line 4
/home/user01/.ssh/known_hosts updated.
Original contents retained as /home/user01/.ssh/known_hosts.old

最后，再重新使用 ssh 连接服务器；

$ ssh root@192.168.21.49
The authenticity of host '192.168.21.49(192.168.21.49)' can't be established.
ECDSA key fingerprint is SHA256:V+iGp3gwSlnpbtYv4Niq6tcMMSZivSnYWQIaJnUvHb4.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.21.49' (ECDSA) to the list of known hosts.