When creating or joining a cluster in RELIANOID, the system exchanges SSH keys between nodes to establish secure communication.

If this exchange fails, you may see the following error in the logs:

(ERROR) cluster :: SSH Keys Ids exchange failed
(ERROR) webgui :: Enabling cluster: SSH Keys Ids exchange failed

Symptoms #

Cluster creation or synchronization fails in the System > Cluster section of the web UI.

The System > Logs > syslog (/var/log/syslog) shows errors similar to:

ssh-copy-id: ERROR: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
ERROR: @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
ERROR: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
ERROR: Host key for 10.x.y.z has changed and you have requested strict checking.
ERROR: Host key verification failed.
(ERROR) cluster :: An error happened copying the Id key to the host 10.x.y.z
(ERROR) cluster :: SSH Keys Ids exchange failed

This indicates that the remote host key has changed or the local node has a conflicting entry in its SSH known_hosts file.

Cause #

The error occurs because:

• The remote cluster node was reinstalled, redeployed, or its SSH host key was regenerated.
• The local node still has the old host fingerprint stored in /root/.ssh/known_hosts.
• As a security precaution, SSH refuses to connect since the stored key does not match the new one.

Resolution #

Remove the old SSH host key entry #

On the node reporting the error, run:

ssh-keygen -f "/root/.ssh/known_hosts" -R "10.x.y.x"

Replace 10.x.y.x with the IP address of the remote node. Apply this command in both cluster nodes including the remote node IP address.

This will remove outdated fingerprints from known_hosts.

Verify the cleanup #

The command should report that entries were found and removed. Example:

# Host 10.x.y.x found: line 1
# Host 10.x.y.x found: line 2
# Host 10.x.y.x found: line 3
/root/.ssh/known_hosts updated.
Original contents retained as /root/.ssh/known_hosts.old

Rebuild the Cluster Service #

Go to the Web UI section System > Cluster

Rebuild or re-enable the cluster configuration.

The SSH key exchange will be attempted again and should succeed now.

Additional Notes #

If you continue to experience issues, ensure that:

• The nodes can reach each other via SSH (ssh root@<REMOTE IP>).
• System clocks are synchronized (use NTP).
• No firewall rules block port 22/TCP between nodes.

After completing these steps, the cluster should build successfully without the SSH Keys Ids exchange failed error.