CentOS Stream 9 – Common Problem 065 – 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

Clients receive `REMOTE HOST IDENTIFICATION HAS CHANGED` alerts.

Environment & Reproduction

After OS reinstall or `ssh-keygen -A` regenerated host keys.

Root Cause Analysis

Server’s host key fingerprint no longer matches client known_hosts.

Quick Triage

Compare with `ssh-keyscan ` and `ssh-keygen -lf `.

Step-by-Step Diagnosis

Verify keys via out-of-band channel before trusting.

Solution – Primary Fix

Remove the old entry: `ssh-keygen -R ` and reconnect.

Solution – Alternative Approaches

Distribute new host keys via configuration management.

Verification & Acceptance Criteria

Clients connect without warnings.

Rollback Plan

Restore prior host keys from backup if reinstall was unintended.

Prevention & Hardening

Back up `/etc/ssh/ssh_host_*` before re-provision.

Related Errors & Cross-Refs

Pairs with cloud-init key regeneration.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

OpenSSH known_hosts management and SSHFP DNS records.