SNTP, Simple Network Time Protocol
In short, ntp client sends UDP request from random port >1023 to port 123 on ntp server. It waits response on the same originating port. Your firewall should be able to keep open originating port for UDP traffic from ntp server. NTP Server: Free Public Internet Time Servers TimeTools is a UK-based manufacturer of NTP servers and precision timing equipment. Based on GPS and Multi-GNSS technology, our products provide a reliable, … 22.13. Checking the Status of NTP Red Hat Enterprise Linux ~]$ ntpstat synchronised to NTP server (10.5.26.10) at stratum 2 time correct to within 52 ms polling server every 1024 s 22.12. Installing the NTP Daemon (ntpd)
Set up NTP on Annke DVR/NVR – ANNKE | Help Center
ESP8266 NodeMCU NTP (Network Time Protocol) Clock Jan 02, 2018 Google turns on free public NTP servers that SMEAR TIME
Internet Time Service Firewall information | NIST
However, you can filter on the well known NTP UDP port 123. Capture only the NTP based traffic: udp port 123; On many systems, you can say "udp port ntp" rather than "udp port 123". External links. Current RFC: RFC 5905 Network Time Protocol Version 4: Protocol and Algorithms Specification. Obsoleted RFCs: RFC 958 Network Time Protocol. RFC NTP 13 (B) - Flag Guys NTP 13(B), FLAGS, PENNANTS AND CUSTOMS, was developed under the direction of the Commander, Naval Telecommunications Command, and is promulgated for use by the U.S. Navy and Coast Guard. Network Time Protocol, NTPv3, NTPv4, Time Servers NTP uses UDP for transport and port 123 for both source and destination. Clock Synchronisation Algorithm. The clock synchronisation algorithm is used by the NTP client when synchronising its clock with an NTP server. The client needs the Round Trip Delay Time and the Offset.