一、今天在使用SSH，连接远程服务器的时候，刚开始是没问题的。
后来阿里云主机重装了一下系统后，再也连不上了。一直报一个错。

~ ⌚ 22:49:52
$ ssh root@47.98.233.15
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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
SHA256:8hgJ8jpcBr1tm6HS72FpXwMrjba8MQqlqYJQLPB/Qf4.
Please contact your system administrator.
Add correct host key in /Users/wangdong/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/wangdong/.ssh/known_hosts:26
ECDSA host key for 47.98.233.15 has changed and you have requested strict checking.
Host key verification failed.

二、解决方法，看错误日志中有一句

Add correct host key in /Users/wangdong/.ssh/known_hosts to get rid of this message.

三、以编辑器的方式进入这个文件

 vi /Users/wangdong/.ssh/known_hosts

四、将红线框部分删除掉

五、再次进行远程连接

~ ⌚ 22:52:18
$ ssh root@47.98.233.15              
The authenticity of host '47.98.233.15 (47.98.233.15)' can't be established.
ECDSA key fingerprint is SHA256:8hgJ8jpcBr1tm6HS72FpXwMrjba8MQqlqYJQLPB/Qf4.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '47.98.233.15' (ECDSA) to the list of known hosts.
root@47.98.233.15's password: 
Welcome to Ubuntu 16.04.3 LTS (GNU/Linux 4.4.0-105-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

Welcome to Alibaba Cloud Elastic Compute Service !

root@iZbp17cj14ulhfrlj02rkaZ:~# 

问题就解决了，原因是因为才重装系统后，再次进行远程连接上，在输入yes后，本机会将远程机器的信息，写到/Users/wangdong/.ssh/known_hosts文件中，所以如果远程重装系统了，本机一定要先清理掉。