NTP / NTS
NTP synchronizes wall-clock time for logs, authentication and certificates. NTS adds authenticated key establishment and protected NTP exchanges. NTP does not replace precision media PTP.
Scope: NTP / NTS — requirements depend on the selected profile.
protocol · Catalog reviewed 2026-09-27
InfrastructureOpen Standard
Infrastructure Requirements
- Reachable time sources
- compatible client/server modes
- TLS trust and NTS support when authenticated time is selected.
Network & Physical Requirements
| Port / allocation | Transport | Connection / signal flow | Feature and requirement | Evidence |
|---|---|---|---|---|
| 123 | UDP | Time client → Configured time server | Profile requirement · Core NTP time synchronization NTPv4 client/server | Source checked 2026-09-27 RFC 5905, Section 7.2: Global Parameters (PORT); Section 8: On-Wire Protocol |
| 4460 | TCP | NTS client → NTS-KE server | Optional · NTS NTS key establishment over TLS NTS-KE The key exchange supplies the NTP server/port parameters; ordinary UDP NTP traffic is still required. | Source checked 2026-09-27 RFC 8915, Section 4: The NTS Key Establishment Protocol |
Gotchas & IT Notes
- ⚠Use approved time sources. Clock accuracy and supported authentication affect certificate and token validation.