How to fix the error “host key verification failed”

After I re-installed AlmaLinux Server on my old Intel NUC, I tried to connect to ssh. The system response message is an error below.

PS C:\Users\Chatr> ssh adminping@192.168.1.111
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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:CqeSzf6sCjCPp63H02E5BqXU7hfjE/YDW2uprgWwqic.
Please contact your system administrator.
Add correct host key in C:\\Users\\Chatr/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in C:\\Users\\Chatr/.ssh/known_hosts:6
Host key for 192.168.1.111 has changed and you have requested strict checking.
Host key verification failed.

Why Host key verification failed!!!

• host key of the remote host was changed from
  • man-in-the-middle attack
  • Reinstall OS on the same machine, but you can backup >> how to backup/restore the host key in ssh server - Ask Ubuntu
• Note: Host key verification is process which make sure you are connecting to the host that you think you are connecting to

How to Fix "Host key verification failed"

Method 1 – removing old key by using the ssh-keygen command

• Syntax

ssh-keygen -R [hostname|IP address]

• Example (At Source Server)

PS C:\Users\Chatr> ssh-keygen -R 192.168.1.111
# Host 192.168.1.111 found: line 6
C:\Users\Chatr/.ssh/known_hosts updated.
Original contents retained as C:\Users\Chatr/.ssh/known_hosts.old

Method 2 – manual removing old key

• Located known_hosts file (Source Server)
  • for root is path /root/.ssh/known_hosts 
  • for non-root is path /home/<your user>/.ssh/known_hosts.
  • bonus windows is path C:\Users\<your user>\.ssh\known_hosts
• Edit known_hosts file with text editor such as nano / vim / or vs code (GUI Mode) etc.
• delete records from known_hosts file and save.

Final Test ssh again

Reference

• Getting started with SSH security and configuration - IBM Developer
• how to backup/restore the host key in ssh server - Ask Ubuntu
• How Does SSH Work? {Detailed Overview} | pNAP KB (phoenixnap.com)
• What is SSH Protocol ❓ How does it work ❓ (wallarm.com)
• SSH Host Based Authentication (wallarm.com)