🔴 Critical   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: RHEL 10.0 RHEL 10.1

📖 ~1 min read

Table of contents
  1. Problem Summary
  2. Symptoms
  3. Diagnostics
  4. Root Cause
  5. Primary Fix
  6. Verification
  7. Prevention
  8. Rollback
  9. Automation
  10. Command Reference
  11. Escalation
  12. Related Notes

Problem Summary

OpenSSH daemon refuses to start after crypto policy changes.

Symptoms

systemctl status sshd shows bad configuration options for ciphers/MACs.

Diagnostics

Run sshd -t and update-crypto-policies –show.

Root Cause

Custom sshd_config conflicts with active system crypto policy.

Primary Fix

Remove deprecated cipher directives and align with policy defaults.

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Illustrative mockup for rhel-10 — rhel10-b02-p35-1
Illustrative mockup — Progressive Robot — Illustrative mockup — Progressive Robot

Verification

Start sshd and test key exchange from modern clients.

Illustrative mockup for rhel-10 — rhel10-b02-p35-2
Illustrative mockup — Progressive Robot — Illustrative mockup — Progressive Robot

Prevention

Run sshd -T checks during config deployment.

Rollback

Restore previous validated sshd_config and restart service.

Automation

Use template-managed sshd settings with policy-aware defaults.

Command Reference

sshd -t; systemctl restart sshd; journalctl -u sshd -b

Escalation

Include /etc/crypto-policies/config and sshd logs.

Emergency access should include console or out-of-band management.

Related tutorial: View the step-by-step tutorial for rhel-10.

View all rhel-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

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