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habrok:additional_information:known_issues [2024/07/16 13:55] – [New server hostkey (21/03/2024 & 15/07/2024)] fokkehabrok:additional_information:known_issues [2025/01/21 09:27] (current) – camarocico
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 This seems to happen for jobs requesting a larger number of nodes, and only with ''mpirun''. Please see this [[habrok:examples:mpi#intel_mpi | Intel MPI]] section for more information about using ''srun'' instead. This seems to happen for jobs requesting a larger number of nodes, and only with ''mpirun''. Please see this [[habrok:examples:mpi#intel_mpi | Intel MPI]] section for more information about using ''srun'' instead.
  
-===== New server hostkey (21/03/2024 & 15/07/2024) ===== 
  
-In order to bring Hábrók back online after the incident on 16/03/2024 we had to reinstall and reconfigure the login and interactive nodes. Because of this, these nodes now have new server host keys. This means that connecting to Hábrók results in (correct) warnings that these keys no longer match those that had been registered on your system when you connected for the first time.  
- 
-On 15/07/2024 we had to reinstall the interactive nodes to fix a configuration issue. 
- 
-Normally, checking the server hostkey ensures that you are not inadvertently connecting to a system posing as Hábrók (known as a man-in-the-middle attack) by warning you that you are actually connecting to another machine. You can safely ignore this check at this time because Hábrók's host keys //have indeed changed// due to the reinstallation. 
- 
-==== MobaXterm ==== 
- 
-When reconnecting you will see a pop up window. Simply press "**Accept the new server hostkey and carry on connecting**" 
- 
-{{:habrok:additional_information:remote_server_id_changed.png?400|}} 
- 
-==== ssh connections on a terminal ==== 
- 
-You will see a message with:  
- 
-<code> 
-@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 
-@    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 ED25519 key sent by the remote host is 
-SHA256:LnOMDB7/5L0OKJojsXb2CovSUGvd2k0U0oJ8L3xR2HI. 
-Please contact your system administrator. 
-Add correct host key in /home/user/.ssh/known_hosts to get rid of this message. 
-Offending ED25519 key in /home/user/.ssh/known_hosts:13 
-  remove with: 
-  ssh-keygen -f "/home/user/.ssh/known_hosts" -R "login1.hb.hpc.rug.nl" 
-Host key for login1.hb.hpc.rug.nl has changed and you have requested strict checking. 
-Host key verification failed. 
-</code> 
- 
-Follow the instructions on the message and run: 
- 
-<code> 
-ssh-keygen -f "/home/user/.ssh/known_hosts" -R "login1.hb.hpc.rug.nl" 
-</code> 
- 
-**Note that your command may be different, as the path to the ''known_hosts'' file is likely different in your situation**. The suggestion in the warning message should give you the correct path.