RutgersTHE STATE UNIVERSITY OF NEW JERSEY
Department of Physics & Astronomy
Center for Materials Theory
← Cluster overview

Typical Problems and Solutions

SSH: Host Identification Has Changed

SSH displays this warning when the server's host key differs from the key saved on your computer. This can happen after a legitimate server rebuild, but it can also indicate that you are connecting to the wrong server.

WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!
Host key verification failed.
  1. Stop the connection attempt. Contact the cluster administrator through a known, trusted channel and ask them to confirm the host-key change and the new SHA256 fingerprint for the exact hostname or IP address you use.
  2. Only after the change is confirmed, remove the old entry for that host. For the submission host:
ssh-keygen -R rupc-01.rutgers.edu

Run this on the computer where you initiated SSH, as your own user. If you connect using a short hostname or an IP address, use that exact name or address instead. For a nonstandard port, use the form ssh-keygen -R '[hostname]:port'. If SSH identifies a different known-hosts file, pass its path with -f.

Reconnect:

ssh YOUR_USERNAME@rupc-01.rutgers.edu

Compare the displayed fingerprint with the one confirmed by the administrator. Accept it only if they match. Do not disable host-key checking or delete the entire known_hosts file.

Administrator reference: on the server itself, the fingerprint of its ED25519 host key can be displayed with:

ssh-keygen -lf /etc/ssh/ssh_host_ed25519_key.pub

The administrator should use the public key file for the key type actually presented by SSH. See the OpenSSH ssh-keygen manual.

Missing Compiler or Numerical Libraries

Load the software environment required by your application before running it. Use the same compiler and library environment when building and submitting a job.

module avail
module list

Choose the required module from the available list, then inspect and load it:

module show MODULE_NAME
module load MODULE_NAME

Replace MODULE_NAME with an actual module name from this cluster. Include the required module-loading commands in your job script. See the quick user guide and its submission templates.

If the error persists, send the administrator the exact error message, the executable name, your job script, and the output of module list. Old Intel 11.1 initialization paths and SMPD settings from the previous cluster should not be added to your .bashrc as a general fix for Rocky Linux 9.