488 private links
As for analyzing the traffic, here’s a useful oneliner that works on Rocky Linux 9. Other operating systems / versions may vary. Adjust the “10000” packet count limit as you see fit.
tcpdump -n -c 10000 inbound and ip and udp and dst port 123 | cut -d" " -f3 | cut -d. -f1-4 | sort | uniq -c | sort -rn | head
Our beloved NTP protocol appears to work in a deep space environment (as tested in a simulation with a 4 hour RTT):
you could use IPv6 for the multicast addresses replacing 224.x.y.z with ff02::xyz or ff02::x:y:z etc.
Rather, the IPv6 multicast address for NTP is ff02::101. Likewise, the multicast IPv4 address for NTP is 224.0.1.1.
PTP daemon (PTPd) is an implementation the Precision Time Protocol (PTP) version 2 as defined by 'IEEE Std 1588-2008'. PTP provides precise time coordination of Ethernet LAN connected computers. It was designed primarily for instrumentation and control systems.
nexpensive, compact GPS unit for highly accurate serial PPS time.
Reviewed in the United States on July 2, 2012
I have the Garmin 18x LVC GPS attached to a serial card installed in a Debian Linux 'Squeeze' box (which was configured using the Setserial, GPSD, and NTP packages).
USB based GPS units are useless for accurately setting the time.
The 18x LVC GPS unit requires 5 volts of power (red wire), and for this I use a specific serial card, the StarTech.com 1 Port PCI RS232 Powered Serial Adapter Card (PCI1S650PW). The card can be configured to supply either 5 or 12 volts (or none) on pin 9 of the RS-232 DB-9 connector, and can draw power either from the PCI bus itself or from the PC power supply directly via the onboard Molex floppy power connector. (I used the latter option). Once the jumpers had been set and the card installed no drivers were required for Debian, Setserial recognizing the card as having a 16550A UART with a baud base of 921600.
The GPS unit itself is mounted externally on the chimney, as the GPS satellite signals are fairly weak, so installing outside is the best option as the GPS itself is weatherproof. For me, this location gives the GPS a clear view of the sky, but the 5 meter (16 feet) cable would not be long enough to reach the computer inside the house, so I replaced almost all of the original serial cable (which is molded onto the 18x LVC). The wires (especially the three signal wires, which includes the PPS) are also VERY thin. So, I cut the original cable close to the GPS unit itself and extended it with my own cable which runs all the way back to the computer and is terminated with a serial DB-9 connector. If you do this, remember to use a shielded cable. There are basically five wires needed for the serial connection: Measurement pulse output (PPS) from the GPS is yellow -> pin 1 (DCD) on the DB-9, transmit is white -> pin 2 (RXD), receive is green -> pin 3 (TXD), ground is black -> pin 5 (GND), and power is red -> pin 9. For the replacement I used a shielded CAT 6 cable and joined each of the pairs together at both ends and used these to give me four of the connections: PPS, transmit, receive, and power (90 mA). I then connected all of the black wires together at the GPS end of the cable and used the drain wire as the ground, connecting it to pin 5 on the DB-9 at the other end. For mounting there is a metric (M3) threaded brass recess on the underside of the 18x LVC.
I also have the StarTech.com PEX1S553LP 1 Port Low Profile Native RS232 PCI Express Serial Card with 16550 UART card installed in a Windows 7 PC which is only used to run firmware updates, etc. on the GPS when needed (as these cannot be performed under Linux). My 18x LVC is updated to version 3.80 (26th March, 2012). For what it's worth, my time1 setting in ntp.conf is 0.035. This gives me the lowest offset and jitter for PPS.
Works like a charm, with extremely low latency PPS time (accurate to a few microseconds).
It’s not NTP. There’s no way it’s NTP. It was NTP
Also known as the Y2K38 Bug, The Unix Y2K Bug or Epochalypse
The year 2038 problem is a problem caused by how some software systems store dates. When these dates reach 1 second after 03:14:07 UTC on 19 January 2038 they could have an error or incorrectly store the wrong date (in some cases 20:45:52 on Friday, 13 December 1901).
On Thursday, Internet pioneer Vint Cerf announced that Dr. David L. Mills, the inventor of Network Time Protocol (NTP), died peacefully at age 85 on January 17, 2024. The announcement came in a post on the Internet Society mailing list after Cerf was informed of David's death by Mills' daughter, Leigh.
"He was such an iconic element of the early Internet," wrote Cerf.
Dr. Mills created the Network Time Protocol (NTP) in 1985 to address a crucial challenge in the online world: the synchronization of time across different computer systems and networks. In a digital environment where computers and servers are located all over the world, each with its own internal clock, there's a significant need for a standardized and accurate timekeeping system.
NTP provides the solution by allowing clocks of computers over a network to synchronize to a common time source. This synchronization is vital for everything from data integrity to network security. For example, NTP keeps network financial transaction timestamps accurate, and it ensures accurate and synchronized timestamps for logging and monitoring network activities.
In the 1970s, during his tenure at COMSAT and involvement with ARPANET (the precursor to the Internet), Mills first identified the need for synchronized time across computer networks. His solution aligned computers to within tens of milliseconds. NTP now operates on billions of devices worldwide, coordinating time across every continent, and has become a cornerstone of modern digital infrastructure.
This server also provides secure Roughtime service. It is monitored and maintained at the same service level as the NTP service provided. The time is synchronized with stratum 1 upstreams.
How to join your linux server to the NTP pool project
This tutorial explains how to configure a NTP (Network Time Protocol) server (using ntpd) and join it to the continuously more demanded NTP pool project. ///
5 servers is preferable (article says 3)
$650.00
LeoNTP Time Server 1200 is a Stratum 1 Master Clock / Time server with GPS synchronised clock source designed from the ground up with the sole purpose of providing a cost effective but highly accurate and extremely high performing networked time server. Extremely easy to setup and configurable with flexible power options USB/PoE (802.3af) it can provide accurate synchronised time for your LAN, WAN, CCTV, PLC, Telephone systems or anywhere accurate standalone time is required.