SLES 15 – Common Problem 137 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Automation pipelines and admins suddenly cannot SSH using previously working keys.

Environment & Reproduction

Triggered after `sshd` config change, SELinux/AppArmor profile update, or home directory permission drift.

Root Cause Analysis

Tightened permissions on `~/.ssh` or `authorized_keys` or sshd `PubkeyAcceptedKeyTypes` excludes the key type.

Quick Triage

Use `ssh -vvv user@host` to capture the negotiation steps and key offers.

Step-by-Step Diagnosis

Inspect `sshd` log via `journalctl -u sshd` and check permissions on `~/.ssh`.

Solution – Primary Fix

Set `chmod 700 ~/.ssh` and `chmod 600 authorized_keys`, then verify sshd config and reload.

Solution – Alternative Approaches

Issue replacement keys using modern algorithms (ed25519) and enforce via policy.

Verification & Acceptance Criteria

All authorised users authenticate over key without password fallback prompts.

Rollback Plan

Restore the previous sshd_config from backup if changes lock out admins.

Prevention & Hardening

Audit `~/.ssh` permissions weekly and centralise key distribution.

Related Errors & Cross-Refs

Often paired with `Permissions 0644 for … are too open` warnings.

Related tutorial: View the step-by-step tutorial for sles-15.

View all sles-15 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

SUSE sshd configuration and AppArmor profile documentation.