Chrony Time Drift Causes Kerberos 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

SSO logins fail with clock skew errors across integrated services.

Environment & Reproduction

VM host resumes or isolated subnet loses NTP reachability.

Root Cause Analysis

chronyd is misconfigured, stopped, or blocked by firewall egress rules.

Quick Triage

Run timedatectl and chronyc sources -v to confirm synchronization status.

Step-by-Step Diagnosis

Check chrony.conf servers, service state, and UDP/123 network reachability.

Solution – Primary Fix

Set valid NTP sources, start chronyd, and allow NTP traffic through firewalld.

Solution – Alternative Approaches

Use internal stratum servers with fallback pools for resilience.

Verification & Acceptance Criteria

chronyc tracking shows normal offset and Kerberos auth succeeds.

Rollback Plan

Revert chrony configuration and restart service to last known working state.

Prevention & Hardening

Monitor offset thresholds and alert when unsynchronized.

Related Errors & Cross-Refs

KRB5KRB_AP_ERR_SKEW, clock skew too great.

Related tutorial: View the step-by-step tutorial for oracle-linux-10.

View all oracle-linux-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

chrony and timedatectl administration guides.