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#ntp
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@mark @M0CUV Perhaps some info here on clocks via GPS, very tantalising rabbit hole....
https://openwrt.org/docs/guide-user/services/ntp/gps
https://github.com/domschl/RaspberryNtpServer
https://github.com/tiagofreire-pt/rpi_uputronics_stratum1_chrony
#gps #stratum1 #ntp #chrony #ntpd
openwrt.org[OpenWrt Wiki] Stratum 1 NTP server using USB GPS
Let's take a moment to remember the guy who made sure we don't have to change Every Goddamn Clock today, David L. Mills, creator of Network Time Protocol (NTP) who passed last year.
My wristwatch is synced to my phone, which is synced to the internet, which knows that time it is right now thanks to David Mills. Cheers to his memory 
Computer Science and EngineeringRemembering alum David Mills, who brought the internet into perfect timeMills created the Network Time Protocol, which enables any device online to know precisely what time it is.
Ein Ofen, der kein #ntp beherrscht, sollte keine #Uhr haben dürfen. #zeitumstellung
Hello, fediverse friends. I have been working on my time server, time.lettersblogatory.com, for several months and have gotten it in pretty good shape. It is now ready for primetime, I hope. If you have an NTP client and would like to give it a try, please add time.lettersblogatory.com to your list of time servers. Bonus: the server is NTS-enabled! It's located in the Netherlands and is a stratum 2 server.
Just like DNS way, way, waaaaaaaay too many seem to mess up NTP. So I wrote a thing about monitoring NTP with OpenSearch/ElasticSearch.
Infosec Worrier · NTP Server Monitoring with Filebeat and ELKthere is a wide gap in the understanding of NTP (and PTP) amongst many IT Organizations. Most appear to be ignorant of RFC8633 containing Best Current Practice (BCP), including recommendations for the stable, accurate, and secure operation of NTP infrastructure.
Did you know chrony, the #NTP implementation, sets up an administrative listener on the loopback interface using UDP/323 by default?
Unfortunately in the #RPKI rpki-rtr has TCP/323 registered with IANA (see IETF RFC 6810). UDP/323 is reserved. Reserving a transport that is unused by the assigned application is common practice these days.
chrony's choice can probably be chalked up to a historical accident since it came first and presumably picked 323 because it "looked" like 123 and was then unassigned.
Chrony should probably change their default imo, but maybe it's too late or not worth it now?
Habe mal wieder ein neues Nerd-Projekt: Ein eigener Stratum 1 NTP-Zeitserver. Warum? Weil es geht. Die Daten kommen per GPS und haben dadurch eine Genauigkeit im Bereich von Nano-Sekunden. Der Testaufbau läuft, jetzt muss ich nur noch ein passendes Gehäuse drucken und eventuell die Antenne noch draußen positionieren.
I pressed the #turbo button on my laptop.
(edited for clarity)
$ sudo hwclock && date && sleep 60 && sudo hwclock && date
22:50:48.433491+01:00
02:29:53 CET 2025
22:51:44.397740+01:00
02:30:54 CET 2025
It can now finish a minue in 56 seconds!
#ThrowbackThursday In 2010 I listed the frequency distribution by major version of #junos routers running in-the-wild. No one had done this before, and I was asked how I was able to do it. At the time I refused to say. Enough time has passed...
A year earlier I had begun surveying the Internet for open #NTP servers after discovering the reflection/amplification threat present in the protocol, but still not publicly disclosed. One of the things I was collecting was mode 6 control readlist responses. The system variable contains OS detail, including version info (although cisco boxes just return "cisco" :-). There were lots of Juniper routers with an open NTP listener in those days. For awhile it was a good way to see what my fellow netops were running.
My newest topic I am trying to understand better: #GNSS
While trying to write about #NTP as well as #PTP another world opened up as well. Global Navigation Satellite System or #GNSS which is most often the source of time. Digging through the different Satellite constellations #GPS , #GALILEO , #BAIDU , #GLONASS and understanding the differences was interesting.
I am still digging deeper. Anyone with knowledge, is highly welcome to educate me. 
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Recently, I moved a server/router/desktop to another motherboard. Upon booting, ping worked, but web browsing didn't. All #DNS lookups were failing.
Turns out the clock was off by half a day. The DNS server couldn't resolve with an incorrect clock, and #NTP couldn't discover the correct time because it couldn't use DNS to look up NTP servers' IP addresses.
So yeah, it's DNS. It's always DNS.
How a Leap Second Became a Leap of Faith in Tech Timekeeping
In the world of precise timekeeping, leap seconds can cause chaos. Discover how one sysadmin ingeniously managed to slow down an entire company's infrastructure by a second to avoid the pitfalls of a ...
https://news.lavx.hu/article/how-a-leap-second-became-a-leap-of-faith-in-tech-timekeeping
How a Leap Second Became a Leap of Faith in Tech Timekeeping
In the world of precise timekeeping, leap seconds can cause chaos. Discover how one sysadmin ingeniously managed to slow down an entire company's infrastructure by a second to avoid the pitfalls of a ...
https://news.lavx.hu/article/how-a-leap-second-became-a-leap-of-faith-in-tech-timekeeping
LED Wall Clock Gets Raspberry Pi Pico Upgrade - When [Rodrigo Feliciano] realized that the reason his seven-segment LED wall clock... - https://hackaday.com/2025/01/01/led-wall-clock-gets-raspberry-pi-pico-upgrade/ #microcontrollers #sevensegmentled #clockhacks #pipicow #kicad #ntp
Hackaday · LED Wall Clock Gets Raspberry Pi Pico UpgradeWhen [Rodrigo Feliciano] realized that the reason his seven-segment LED wall clock wasn’t working was because the original TG1508D5V5 controller was fried, he had a decision to make. He could…
Small little video about setting up #NTP on #OPNSense 
while also leveraging #systemd (timesyncd) to keep track of time. 
Enjoy everyone
#Youtube
https://www.youtube.com/watch?v=f6tBKsqKnNo
#Odysee
https://odysee.com/@YetanotherSysAdmin:0/Setting-up-NTP-on-OPNSense:a
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Risico's computerklokken terugzetten
@yamuis : jaaaren geleden heb ik tijdkritische communicatieroutines voor microcontrollers geschreven (in "assembler"). Het detecteren van timeouts voelt dan al als een blok aan je been, en je hebt (neemt) dan "geen tijd" om op negatieve tijdverschillen te checken.
Oftewel, de meeste low-level software gaat ervan uit dat tijd altijd "toeneemt". Als je een computerklok terugzet in de tijd heb je zelden een volledig overzicht op de consequenties daarvan.
Als dat onverhoopt nodig is, kun je het beste alle netwerkverbindingen afsluiten en/of verbreken en even tijd geven om te time-outen. Dan de klok terugzetten en de boel weer aanslingeren.
Niet voor niets zijn er protocollen zoals ntp die systeemklokken met zeer kleine stapjes corrigeren.
Y2K was geen probleem voor low-level software omdat die zelden of nooit terugrekent uit jj-mm-dd, maar baseert op een systeemklok die per seconde tikt (of frequenter).
Een potentieel wél groot probleem kan ontstaan op 19 januari 2038. Uitleg (Engelstalig) is te vinden in https://en.wikipedia.org/wiki/Year_2038_problem (onderstaand animated GIFje is afkomstig uit die pagina).
GIF
I’ve had a stratum-1 pi in my house for like ten years now - it’s probably my favorite project I’ve ever done.
That’s also ten years of contributions to the #ntp pool. It’s a nice way to help. https://mastodon.social/@jpmens/113723977797322342
MastodonJP Mens (@jpmens@mastodon.social)"how to create a stratum-1 NTP Server using a Raspberry Pi utilizing GPS and PPS, and get time within 100 nanoseconds of real time, directly from the atomic clocks located in the GPS satellites above your head. The best part about this guide is that this will work with no internet."
https://blog.networkprofile.org/gps-backed-local-ntp-server/
Bueno, estuve trabajando un poco en la página del servidor NTP, ahora aparece una gráfica del GPS fix con la señal ruido, los satélites utilizados y un java applet que muestra el tiempo universal y local en el navegador. Todo un departamento de Metrología che https://undernet.uy/ntp/ #ntp #stratum1 #undernet #metrología #metrology #time #tiempo #tiempouniversal #universaltime #astronomy #uruguay
undernet.uyUndernet Uruguay: Servidor Comunitario Autogestionado