HPC Cluster ELSA3 Host Key Change: Difference between revisions
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When trying to connect to '''elsa.hpc.tcnj.edu''' using SSH after the ELSA3 upgrade, you will probably get an error about the host key or host identification changed. | When trying to connect to '''elsa.hpc.tcnj.edu''' using SSH after the ELSA3 upgrade, you will probably get an error about the host key or host identification changed. | ||
Below are instructions on how to resolve this error when using the command-line SSH program on Mac OS X, but the commands are identical if you are using Linux or the Microsoft Windows built-in SSH client. Near the bottom of this page are instructions if you are on Microsoft Windows and using PuTTY or MobaXterm SSH client software. | Below are instructions on how to resolve this error when using the command-line SSH program on Mac OS X, but the commands are identical if you are using Linux or the Microsoft Windows built-in SSH client. Near the bottom of this page are instructions if you are on Microsoft Windows and using PuTTY or MobaXterm SSH client software. If you are using a different SSH client, you will need to consult its documentation for instructions on how to resolve host key issues. | ||
== SSH on MacOS X/MS-Windows/Linux == | == SSH on MacOS X/MS-Windows/Linux == | ||
Revision as of 15:07, 30 April 2026
Remote Host Key/Identification Changed Error
When trying to connect to elsa.hpc.tcnj.edu using SSH after the ELSA3 upgrade, you will probably get an error about the host key or host identification changed.
Below are instructions on how to resolve this error when using the command-line SSH program on Mac OS X, but the commands are identical if you are using Linux or the Microsoft Windows built-in SSH client. Near the bottom of this page are instructions if you are on Microsoft Windows and using PuTTY or MobaXterm SSH client software. If you are using a different SSH client, you will need to consult its documentation for instructions on how to resolve host key issues.
SSH on MacOS X/MS-Windows/Linux
When attempting to use the terminal SSH client, you will see a message similar to the screenshot below stating WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!, followed by some additional "scary" text and finally the message that the Host key verification has failed. Note that the text may vary slightly based on the operating system (Mac/Windows/Linux) you are using. This was captured on a Mac.
To resolve the issue, you need to remove the old host key for elsa.hpc.tcnj.edu so that you can accept the new one. To do so, run the command ssh-keygen -R elsa.hpc.tcnj.edu in the terminal. Your output should be similar to the screenshot below. Again, it may vary based on your operating system, but you want to see that it found elsa.hpc.tcnj.edu and updated the file.
After the existing host key has been removed, you can run the ssh command in your terminal again. This time it will ask you to accept the new host key. If accepted, it won't ask you again the next time. You need to type the full word yes and press the ENTER/RETURN key.
That's it. You can now continue to use the ELSA3 HPC cluster.
PuTTY on Microsoft Windows
Resolving the host key/identification change when using PuTTY is pretty straightforward. Simply click the Accept button to replace the old host key with the new one.
MobaXterm on Microsoft Windows
Resolving the host key/identification change when using MobaXterm is straightforward. Simply click the OK button to replace the old host key with the new one.
