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NTP Time Synchronization

Problem Statement​

  • Security Challenge: Clock drift breaks Kerberos, SSO, TLS validation, and log correlation.
  • Real-World Scenarios: AD-integrated environments require 5-minute skew or less; drift causes authentication failures.
  • Business Context: Failed logins and invalid certificates disrupt access and auditing, increasing support load.

Key Benefits​

  • Desired Outcome: Precise and reliable system time aligned with enterprise time sources.
  • Value Proposition: Stable SSO, accurate TLS checks, and consistent audit trails.
  • Competitive Advantage: Predictable authentication at scale versus unmanaged host time.

Prerequisites​

  • Client-Side Preparations: Identify enterprise NTP servers or domain controllers providing time.
  • SafeSquid-Side Setup: Confirm host firewall allows UDP 123 to enterprise NTP.
  • System Requirements: chrony or ntpd supported on the OS; stable network connectivity.

Call to Action​

  1. Install time synchronization service.
    • Prefer chrony.
      • Debian/Ubuntu: 
        sudo apt update
        sudo apt install -y chrony
      • RHEL/Rocky: 
        sudo dnf install -y chrony
      • Verification: chronyd -v prints version.
  2. Configure servers.
    • Edit /etc/chrony/chrony.conf (Debian/Ubuntu) or /etc/chrony.conf (RHEL): 
      server ntp1.enterprise.tld iburst
      server ntp2.enterprise.tld iburst
      # For AD: prefer DCs and set minimal sources to 2
      makestep 1.0 3
      driftfile /var/lib/chrony/chrony.drift
      logdir /var/log/chrony
    • Verification: chronyc sources -v lists servers with reach > 0.
  3. Enable and start service. 
    sudo systemctl enable --now chronyd
    systemctl is-active chronyd
    systemctl is-enabled chronyd
    • Verification: active and enabled.
  4. Validate synchronization. 
    chronyc tracking
    chronyc sourcestats -v
    • Verification: Stratum, Reference ID, and System time offset within milliseconds.
  5. Align SafeSquid authentication.
    • For SSO/Kerberos: Confirm SafeSquid host time skew within 5 minutes of AD.
    • Verification: Authentication succeeds; no KRB5 clock skew errors in logs.

Solution Verification​

  • Interface Checks: N/A (service daemon). Verify with chronyc tracking output.
  • Log Analysis: Review /var/log/chrony/chrony.log and system journal for sync events and step corrections.
  • Performance Validation: Confirm no new SSO failures; TLS validations proceed without date errors.
  • Screenshots: /img/supporting-services/chrony-tracking.webp with alt text "chronyc tracking showing synchronized time".

Troubleshooting Guide​

  • Common Issues & Scenarios:
    • No synchronization: UDP 123 blocked or wrong server names.
    • Frequent step corrections: Unstable time source or VM host time interference.
    • Kerberos failures: Clock skew beyond maximum tolerance.
    • TLS errors on valid sites: Incorrect system date or timezone.
  • Resolution Steps:
    • Open UDP 123 to enterprise NTP; verify DNS for server FQDNs.
    • Pin stable NTP servers; disable hypervisor time sync if conflicting.
    • Run chronyc makestep after large corrections; re-test SSO.
    • Set correct timezone with timedatectl set-timezone and confirm NTP sync.
  • Escalation Procedures:
    • Collect timedatectl, chronyc tracking, chronyc sources -v, and logs.
    • Contact SafeSquid support with environment details and outputs.