IBM AIX 7.1 – Common Problem 124 – 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 see ‘REMOTE HOST IDENTIFICATION HAS CHANGED’ connecting to AIX 7.2.

Environment & Reproduction

Host key regenerated after sshd reinstall or fresh build from mksysb.

Root Cause Analysis

Client cached the previous host key in ~/.ssh/known_hosts.

Quick Triage

Confirm the AIX 7.2 host key with ssh-keygen -lf /etc/ssh/ssh_host_*.pub.

Step-by-Step Diagnosis

Compare with the client’s known_hosts entry for the host.

Solution – Primary Fix

Have the client remove the old entry with ssh-keygen -R HOSTNAME.

Solution – Alternative Approaches

Distribute the new host key via configuration management or known_hosts pins.

Verification & Acceptance Criteria

ssh from the client succeeds without the host-changed warning.

Rollback Plan

If the key change was unintended, restore the previous ssh_host_* from backup.

Prevention & Hardening

Pin host keys via configuration management and rotate on a schedule.

Related Errors & Cross-Refs

Pairs with sshd refusing connections during MITM checks.

Related tutorial: View the step-by-step tutorial for aix-7.1.

View all aix-7.1 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

IBM Docs: OpenSSH on AIX, host key management.