RHEL 9: SSH Key Authentication Fails

📖 ~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

SSH key login is rejected and users are prompted for password unexpectedly.

Environment & Reproduction

Use `ssh -vvv user@host` and verify server-side `/etc/ssh/sshd_config` directives.

Root Cause Analysis

Confirm OpenSSH packages and versions with `rpm -q openssh openssh-server`.

Quick Triage

Inspect `systemctl status sshd` and ensure config test passes with `sshd -t`.

Step-by-Step Diagnosis

Read auth events via `journalctl -u sshd -b` for permission or key parsing errors.

Solution – Primary Fix

Set correct ownership/permissions on `~/.ssh` and `authorized_keys`, then reload sshd.

Solution – Alternative Approaches

Confirm SSH service is allowed in the active `firewalld` zone.

Verification & Acceptance Criteria

Restore user home contexts with `restorecon -Rv /home//.ssh` if labels are incorrect.

Rollback Plan

Reconnect in a fresh session and verify key auth remains functional after reboot.

Prevention & Hardening

Apply account hardening templates and periodic permission audits.

Related Errors & Cross-Refs

Keep at least one console or break-glass account before tightening SSH settings.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Consult `man sshd_config` and OpenSSH security best practices.