Connection Warnings
The first time you connect to a system using ssh from any given machine, you may encounter a warning such as this:
The authenticity of host 'csslab1.uwb.edu (69.91.198.161)' can't be established. RSA key fingerprint is 9d:03:dd:3f:19:a0:19:d3:22:6a:33:93:c4:9e:2d:b5. Are you sure you want to continue connecting (yes/no)? Type in yes
SSH uses public key cryptography to ensure that when you connect to a machine, your session is not hijacked by an attacker. By verifying the fingerprint your ssh client is asking about against a list of known fingerprints, you can know that your connection is going to the machine you think it is. Most people skip this step and just accept any fingerprints their ssh client asks them about.
Graphical ssh clients such as PuTTY may display a dialog about the key fingerprint. Most will ask if you want to save the key for future use. This is generally a good idea, since it means you don’t have to see the message every time you connect.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@ 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 SHA256:2mnui10y7jn99/kkkkkkyjfrewwwwwerer. Please contact your system administrator. Add correct host key in /users/username/.ssh/known_hosts to get rid of this message. Offending ECDSA key in /users/username/ .ssh/know_hosts:15 ECDSA host key for something@uwb.edu has changed and you have requested strict checking. Host key verification failed.
From the command line: Type
$ ssh-keygen -R [hostname or IP address]
For example using csslab4 machine, you would type it in like shown below:
$ ssh-keygen -R csslab4.uwb.edu