🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: CentOS Stream 10

📖 ~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 refuse to connect with `REMOTE HOST IDENTIFICATION HAS CHANGED` after host reimaging.

Environment & Reproduction

Common after rebuilding a host without preserving SSH host keys.

Root Cause Analysis

New host keys conflict with the entries stored in client known_hosts files.

Quick Triage

Confirm new fingerprint with `ssh-keyscan -t ed25519 host`.

Step-by-Step Diagnosis

Compare against the known_hosts entry and verify the rebuild was authorized.

Illustrative mockup for centos-stream-10 — terminal_or_shell
SSH host key mismatch after reinstall diagnostics in terminal — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Remove the stale entry with `ssh-keygen -R host` and trust the new fingerprint.

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Illustrative mockup for centos-stream-10 — logs_or_journal
journal and log evidence for SSH host key mismatch after reinstall — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Use SSH certificates so client trust is anchored on a CA rather than per-host keys.

Verification & Acceptance Criteria

Clients connect without host key warnings.

Rollback Plan

Restore prior host keys from backup if available to avoid re-trusting from scratch.

Prevention & Hardening

Back up `/etc/ssh/ssh_host_*` to your config management vault for restoration.

Related to client known_hosts churn and SSH CA rotation events.

Related tutorial: View the step-by-step tutorial for centos-stream-10.

View all centos-stream-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

OpenSSH host key management documentation.

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