Ubuntu 18.04 Time Sync Drift Causes TLS and Login Issues

📖 ~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

SSL validation, domain login, and scheduled jobs fail due to clock drift.

Environment & Reproduction

Common on VMs with paused hosts or blocked outbound NTP traffic.

Root Cause Analysis

Disabled time sync service or unsuitable NTP sources cause large offset.

Quick Triage

Check timedatectl for synchronization state and current time offset.

Step-by-Step Diagnosis

Inspect systemd-timesyncd logs, NTP reachability, and hypervisor guest tools status.

Solution – Primary Fix

Enable NTP sync, configure approved time servers, and force immediate resync.

Solution – Alternative Approaches

Deploy chrony where stricter correction and tracking controls are required.

Verification & Acceptance Criteria

Offset remains low and TLS or Kerberos authentication succeeds consistently.

Rollback Plan

Revert to previous NTP configuration if custom server set is unreachable.

Prevention & Hardening

Monitor clock offset and alert on sustained drift thresholds.

Related Errors & Cross-Refs

Certificate not yet valid, clock skew too great, failed Kerberos preauth.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

timedatectl, systemd-timesyncd, and chrony operational references.