1598559 : ssh to naf not possible

Created: 2026-05-05T19:00:43Z - current status: open

Summary of the Issue

A user experienced a sudden disconnection while working on the National Analysis Facility (NAF) via VS Code. Upon attempting to reconnect via SSH (ssh [USERNAME]@naf-atlas.desy.de), they encountered an error:

"Remote host identification has changed"

This suggests a potential security-related issue, such as a server key update or a man-in-the-middle attack warning.

Possible Solution / Next Steps

  1. Verify the Host Key Change
  2. The error indicates that the remote server’s SSH key has changed. This can happen if:
    • The server was reinstalled or updated.
    • The user is connecting to a different machine (e.g., due to load balancing).

  3. Action: Check if the key change was intentional by contacting [uco@desy.de] or the ATLAS-specific support (naf-atlas-support@desy.de).

  4. Update the Known Hosts File

  5. If the change is confirmed to be legitimate, remove the old key from ~/.ssh/known_hosts: bash ssh-keygen -R naf-atlas.desy.de

  6. Then reconnect to accept the new key.

  7. Check for Temporary Outages

  8. If the issue persists, it may be a temporary service disruption. The user should monitor DESY’s status page or contact support for updates.

  9. Alternative Connection Methods

  10. If SSH remains unstable, try:
    • Using a different network (e.g., VPN if off-site).
    • Adjusting SSH settings (e.g., ServerAliveInterval in ~/.ssh/config).

Sources Used