We have updated the SSH server and the ECDSA key due to security reasons.
Since the ECDSA key has changed you might get a warning while connecting to hexagon, similar to the following:
---------------------------------------------------------------------------------------------------------------------------------
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ 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
-- LINE REMOVED BY SYSADMIN --.
Please contact your system administrator.
Add correct host key in ~/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in ~/.ssh/known_hosts:1
remove with: ssh-keygen -f "~/.ssh/known_hosts" -R hexagon.bccs.uib.no
ECDSA host key for hexagon.bccs.uib.no has changed and you have
requested strict checking.
Host key verification failed.
-------------------------------------------------------------------------------------------------------------------------------

Please note that other keys were not changed and if you get similar error but not referring to the ECDSA key, do not follow the procedure below.

Please run the following commands:
ssh-keygen -f "~/.ssh/known_hosts" -R hexagon.bccs.uib.no
ssh-keygen -f "~/.ssh/known_hosts" -R hexagon

In case you still encounter problems connecting to hexagon please run your ssh command with "-v" option for verbose output and post it to HPC support for help.