If provided key or fingerprint doesn't match with stored value, return "update", if no value is found for a given host, return "add", otherwise return "exists".If neither key, nor fingerprint is defined, then additional validation is not performed.Then you can open the Java Script console (CTRL Shift J) and type the following into the console.Check the record in known_hosts file, either by its value or by fingerprint (it's enough to set up either key or fingerprint, you don't need to set up both).RSA key fingerprint is 8c:5b:5e:69:a:f5:7d:4a:9a:d3:4c:fe:3f:43. Are you sure you want to continue connecting (yes/no)?If you answer no, the login process stops and you are given a simple error message.This is to protect you from “man in the middle” and similar attacks where an attacker tries to insert themselves between you and your desired host.If your client thinks something is amiss you will see a warning similar to the following but if you see this warning don’t panic.
This whole procedure will take less of 30 minutes to complete.
Some ssh clients may ask you right after the warning if you want to continue and skip the host key verification step altogether (which can also be done by passing in the appropriate option to ssh).
As I mentioned though, this is a safeguard meant for your protection and should not normally be circumvented.
It sounds complicated, but you don’t have to worry about it! Here’s an example of what you should see on that first attempt (this will vary based on your OS).
The authenticity of host '[example.com]:22 ([10.2.139.23]:22)' can't be established.