RHEL 8 – chronyd Unsynchronized Time Causes Authentication Failures

📖 ~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

Clock drift causes Kerberos, TLS, and token-based authentication failures across services.

Environment & Reproduction

Seen on systems with blocked NTP egress or invalid chrony source configuration.

Root Cause Analysis

chronyd cannot reach acceptable sources or source selection never stabilizes.

Quick Triage

Check systemctl status chronyd, chronyc tracking, and review chronyd logs in journalctl.

Step-by-Step Diagnosis

Validate source reachability, DNS resolution, and firewalld allowances for UDP 123.

Solution – Primary Fix

Correct chrony.conf sources, restart chronyd, and use chronyc makestep where policy permits.

Solution – Alternative Approaches

Point hosts to internal enterprise NTP servers when internet time sources are blocked.

Verification & Acceptance Criteria

timedatectl reports synchronized, chronyc tracking offset remains within operational threshold.

Rollback Plan

Restore previous chrony.conf backup and restart chronyd if new sources prove unreliable.

Prevention & Hardening

Monitor drift and synchronization status centrally and alert when stratum or offset degrades.

Related Errors & Cross-Refs

System clock unsynchronized, source unreachable, authentication token not yet valid.

Related tutorial: View the step-by-step tutorial for rhel-8.

View all rhel-8 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

RHEL 8 chrony and time synchronization operations documentation.