SSH permission denied (publickey) authentication failed

What this failure means

SSH authentication to a Git host or remote server failed with explicit “Permission denied (publickey)” message. The private key is missing, not readable, or the public key is not registered on the server.

Symptoms

Faultline looks for one or more of these log fragments:

Permission denied (publickey)
git@.*Permission denied

Diagnosis

SSH permission errors occur when:

• The SSH private key file is missing or not in the expected location.
• The private key has incorrect file permissions (too permissive for the key itself or parent directories).
• The public key is not added to the SSH server’s authorized_keys.
• SSH agent is not running or the key was not added with ssh-add.
• The SSH host key (known_hosts) is not recognized.
• The CI environment has no SSH support configured.

The error explicitly shows Permission denied (publickey), indicating the public key authentication path was attempted but rejected.

Fix steps

1. Confirm the SSH private key file exists and has correct permissions:

   ls -la ~/.ssh/id_rsa
   chmod 600 ~/.ssh/id_rsa
   chmod 700 ~/.ssh
   

2. If using GitHub or similar, verify the public key is registered:

   ssh -T git@github.com 2>&1 | head -5
   

3. If running in CI (GitHub Actions, GitLab CI, etc.), configure SSH with the correct secret:

   GitHub Actions example:

   - uses: webfactory/ssh-agent@v0.7.0
     with:
       ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
   

4. If the SSH host key is not recognized, add it with ssh-keyscan:

   ssh-keyscan github.com >> ~/.ssh/known_hosts
   

5. Test the SSH connection:

   ssh -v git@github.com
   

Validation

• ssh -T git@github.com returns Hi <username>! You've successfully authenticated... (or similar success message).
• ls -la ~/.ssh/id_rsa shows 600 permissions on the key.
• Re-run the CI job.

Why it matters

SSH failures block Git operations (clone, fetch, push) and prevent code deployment. Misconfigured keys are a frequent source of CI/CD pipeline breakdowns.

Prevention

• Use SSH key management tools (ssh-agent, key managers) in CI environments.
• Document SSH setup in your CI configuration.
• Use strong, dedicated SSH keys for CI vs. development.
• Regularly audit which public keys are registered on your Git hosts.

Try it locally

ssh -v git@github.com
ls -la ~/.ssh
ssh -T git@github.com

How Faultline detects it

Use faultline explain ssh-permission-denied to see the full playbook.

faultline analyze build.log
faultline explain ssh-permission-denied

Generated from playbooks/bundled/log/auth/ssh-permission-denied.yaml. Do not edit directly.