Unable to SSH into a Google Compute Engine (GCE) Instance

Problem:

A user is unable to connect to their GCE instance using SSH, and they receive an error message like "Permission denied" or "Connection timed out."

Solution:

1. Check Firewall Rules: Ensure that the firewall rules allow SSH (port 22). In the Google Cloud Console, navigate to VPC network → Firewall rules and verify that the SSH rule is enabled.

2. Verify SSH Key Configuration: If you’re using SSH keys for authentication, ensure the correct public key is added to the instance metadata. You can do this by:

• Go to Compute Engine → Metadata.

• Select SSH Keys and ensure your public key is listed.

3. Restart SSH Service: Try restarting the SSH service on your instance via Google Cloud Console by using the gcloud tool.

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gcloud compute ssh instance-name --zone zone-name

sudo systemctl restart ssh

4. Review Logs: If the above steps do not work, check the instance logs to troubleshoot:

• Go to VM instances → Select your instance → Logs and review any SSH-related errors.