问题
当执行推送命令的时候，出现如下错误：
$ git push fork my_branch
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
The RSA host key for github.com has changed,
and the key for the corresponding IP address 20.205.243.166
is unknown. This could either mean that
DNS SPOOFING is happening or the IP address for the host
and its host key have changed at the same time.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ 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 RSA key sent by the remote host is
SHA256:uNiVztksCsDh.....
Please contact your system administrator.
Add correct host key in /Users/kemix/.ssh/known_hosts to get rid of this message.
Offending RSA key in /Users/kemix/.ssh/known_hosts:5
RSA host key for github.com has changed and you have requested strict checking.
Host key verification failed.
fatal: 无法读取远程仓库。请确认您有正确的访问权限并且仓库存在。问题分析
刚开始以为是ssh key的问题，通过命令重新生成了
$ ssh-keygen -t rsa -b 4096 -C "我的邮箱"
然后在github上重新添加新的rsa公钥“id_rsa.pub”，依旧没有改善。
看错误内容，貌似是“known_hosts”的锅，打开发现与错误提示一致，是因为github.com的IP变更了（正式因为本人好久没有用github提交代码了，都没有尽早发现）。
问题解决
第一步、在“known_hosts”中删除github.com相关行。
第二步、重新拉取下代码，此步骤主要是为了自动生成最新的github.com项，否则会报如下错误：
ssh_exchange_identification: Connection closed by remote host
fatal: 无法读取远程仓库。请确认您有正确的访问权限并且仓库存在。
所以当执行拉取命令，并在提示时，回答yes同意：
$ git pull
The authenticity of host 'github.com (20.205.243.166)' can't be established.
ECDSA key fingerprint is SHA256:p2QAMXNIC1TJYWeIOttrVc98/R1BUFWu3/LiyKgUfQM.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'github.com,20.205.243.166' (ECDSA) to the list of known hosts.
然后就可以快乐的推送自己的fork分支代码了
思考
所以同样道理，一旦以后遇到诸如域名与IP绑定有变更，而导致类似的ssh连接方式出现问题，关键是在“known_hosts”中删除旧的相关项，重新生成即可。
