5 ms·
The Thorny Problem of Keeping the Internet's Time
- egberts1 4y agoDon’t forget to add “ maxdelay 0.05/0.1/0.2” across your three NTP server settings, lest you get hit by MitM NTP attack. You’re welcome.
- mitchbob 4y agoArchived: https://archive.ph/tmbk6 https://archive.ph/tmbk6
- adamgordonbell 4y agoI had written David and NTP down as a podcast episode idea. Never expected to get scooped by the New Yorker.
- htopg 4y agoAn intricate topic like this works better as a written article. Podcasts are more for people who want to listen to some lowbrow stuff while driving.
- one_more_q 4y agoSorry but this is just your opinion. I Listen to tons of very technical podcasts and it works great. If you are interested in technology, check out the omega tau podcast for example.
- psYchotic 4y agoOr, ironically, the podcast of the guy he responded to, adamgordonbell: https://corecursive.com/ https://corecursive.com/ It's a podcast I've really been enjoying for a few years now. It used to be a little more technical (as the name, corecursive, kinda implies), but found a niche in interviewing people more about the people than the tech they're knowledgeable about, which is also very pleasant. Anyway, I encourage you to listen to both an early and a recent episode to find out if you like it.
- someguydave 4y agoThis article is pretty lowbrow, not much technical meat and lots of ephemeral kibitzing.
- andirk 4y agoI call them subscription mp3 audio files.
- jdougan 4y agoDo it anyways. Dave Mills and NTP deserves it. Also: Olson timezone database and its various maintainers. Paul Eggert is the current maintainer, I think. Arthur David Olson could be interesting as well.
- photochemsyn 4y agoComputerphile has a really amusing (sort of) video on the related issue of how to translate between internet time and local time zones (though they have a different opinion about the wisdom of 'leap smears' vs 'leap seconds'): https://www.youtube.com/watch?v=-5wpm-gesOY https://www.youtube.com/watch?v=-5wpm-gesOY Note that the common-sense notion that time intervals are fixed fails when relativistic concepts are introduced. Atomic clocks get out of sync due to being in different relativistic frames (satellites vs. ground, for example). Hence designating a 'universal time' is always going to be somewhat arbitrary. https://blog.swiftnav.com/relativistic-correction/ https://blog.swiftnav.com/relativistic-correction/
- neilv 4y ago> Mills wrote, in a 2003 paper. “Today, the Sun never sets or even gets close to the horizon on NTP.” I'd guess the capitalized "Sun" was a pun, for the Sun Microsystems computers that still ran much of the Internet. For example: https://www.sunmanagers.org/1992/1188.html https://www.sunmanagers.org/1992/1188.html
- andylynch 4y agoIt’s a play on a well-known description of the extent of the British Empire in its time. And which still, if you squint a bit, remains true today, at least according to Randall Munroe* * https://what-if.xkcd.com/48/ https://what-if.xkcd.com/48/
- neilv 4y agoThanks, great information. (I'd heard the saying, but I see capitalized Sun so much to refer to the computers, that I guess I always read it that way, and forgot our star is also capitalized.)
- imglorp 4y agoSun definitely advanced the state of the art. They had a well written set of three Blue Papers on timekeeping in SunOS, if you can find them after Oracle ate everything. Their implementation was mostly Mills ntpd but had to tweak it for their motherboard realtime clocks. Both ntpd and the Sun RTC were the source of much debugging amusement. But that's another story :-)
- rzimmerman 4y agoThis is a really great article that doesn’t shy away from technical aspects while putting a human face on NTP. It’s really cool to learn the history behind something we take for granted.
- amdelamar 4y agoI also really enjoyed reading this; the mix of computer science & history was well balanced and kept my interest. It makes me think there should be a CompSci history class taught in college.
- whoibrar 4y agoThis quote hits hard Coders who contribute to it, she said, should feel proud enough to declare, “Everyone uses the software, it’s in everything, and I wrote it!” It’s striking how few people know Mills’s name, given how many know the pseudonym of whoever created Bitcoin." I never heard of Mill before, and am just glad to have read and known this critical man and technology to internet infrastructure.
- Sniffnoy 4y agoI mean, I think Satoshi Nakamoto is notorious precisely because of his pseudonymous nature. If he'd used his real name, I doubt he'd get nearly as much attention.
- mdbauman 4y agoRelevant xkcd: https://xkcd.com/2347 https://xkcd.com/2347 I was a little sad to read that Mills in fact lives in Delaware, not Nebraska. I always had a sneaking suspicion that this comic was NTP-related.
- Maursault 4y agoTo be fair, that's only off by 0.0069625621 seconds. Since time advances at the speed of light, you could say everyone lives in Nebraska and still be correct well within the margin of error.
- bjeanes 4y agoThe title text for the image implies it might be about ImageMagick, but that's probably dated now since the likes of vips
- amdelamar 4y agohttps://www.nwtime.org/current-members-donors/ https://www.nwtime.org/current-members-donors/
- geerlingguy 4y agoTime has been on my mind a lot lately, testing the OCP's Time Card, working with bringing up PTP on the Raspberry Pi CM4, and most recently interviewing Dr. Demetrios Matsakis, who was one of the people who coordinated UTC for many years (and now works as chief scientist at a local clock/timing company). It's always fascinating how certain individuals can really push things forward in a much greater way than you'd think. NTP changed a lot of what's possible online and in software, by giving a reliable more centralized timing solution for much of the world (still to this day). But talking to some actual experts in the field (like Dr. Matsakis), it's fascinating some of the additional problems you encounter when Internet, LAN, and even GPS connectivity can't be guaranteed, but you still need many devices with microsecond-level accuracy for long periods of time.
- manv1 4y agoTalk to any developer who's been around for any period of time, and they'll tell you that dealing with time is a PITA. What's bad is that there's no real thought given to interplanetary time. It's alluded to occasionally in SF, but there are no RFCs etc about it. Earth has UTC. Mars will presumably have MTC. What about things wandering about? How will that be mapped? More importantly, what happens to timestamps, GUIDs, etc?
- vageli 4y agoReal thought has indeed been given to interplanetary time (even by the subject of TFA). You may find this of interest: https://webcache.googleusercontent.com/search?q=cache:pyKjMozcdzEJ:https://www.eecis.udel.edu/~mills/database/brief/ipin/ipin.ps&cd=11&hl=en&ct=clnk&gl=us https://webcache.googleusercontent.com/search?q=cache:pyKjMo... (forgive the cache but a postscript file is more easily viewed this way in the browser).
- zokier 4y agoFew other relevant pointers: https://en.wikipedia.org/wiki/Deep_Space_Atomic_Clock https://en.wikipedia.org/wiki/Deep_Space_Atomic_Clock and https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time
- wrycoder 4y agoThere is an implementation: Martian Time in Hare[0], which is based on the Martian Business Calendar[1] [0] https://harelang.org/blog/2022-08-01-martian-time-in-hare/ https://harelang.org/blog/2022-08-01-martian-time-in-hare/ [1] http://www.bdm.id.au/calendar/mars_calendar.html http://www.bdm.id.au/calendar/mars_calendar.html
- Maursault 4y ago> Earth has UTC. Mars will presumably have MTC. If UTC doesn't work on Mars, it's false advertising, and we should really change the name.
- 4y ago
- snailmailman 4y agoI’ve recently gotten curious about how accurate my computers clock is, and the answer is “usually, only vaguely accurate down to one second” I check via time.gov, and it’s often off by .5-.8s which just seems kinda insane to me. On my phone it’s always accurate to around .01s. I think I have a guess as to why though. The bios clock might not save milliseconds[0]. So whenever I turn the computer on in the morning, it’s always not synced to the second. And windows just doesn’t care? Even if it’s off by 900ms and I manually go in and try to resync it often won’t bother. I have to manually change it to something blatantly wrong, then resync. And only then will it will finally be accurate to to .01s. This seemingly default level of imprecision to nearly 1 full second is very surprising to me. I’m curious if that affects anything. [0] not 100% certain about this. Maybe I just have insane second-per-day drift. I’ve seen the computer be off by as much as 1.3s, which doesn’t quite match my theory, but that error is enough to resync on its own.
- adrian_b 4y agoI have not checked if in recent versions of Windows there has been any change, but previously by default the computer clock was synchronized with a time server only once per day, so until the next synchronization it is normal to accumulate a time difference up to one or two seconds. I do not know how many Linux distributions enable by default a ntpd daemon, but I have always enabled it on any computer running Linux or FreeBSD. When a ntpd is active, it adjusts continuously the local clock based on comparisons with NTP servers, so the time cannot be wrong by more than a few milliseconds. Therefore the error becomes 100 to 1000 times less than without ntpd. The time differences between computers using NTP on the same LAN are smaller, usually of a few hundred microseconds. For even better synchronization within a LAN, the Precision Time Protocol must be used.
- seanc 4y agoFound this on a deep man page, but I can't remember which one: Our units of temporal measurement, from seconds on up to months, are so complicated, asymmetrical and disjunctive so as to make coherent mental reckoning in time all but impossible. Indeed, had some tyrannical god contrived to enslave our minds to time, to make it all but impossible for us to escape subjection to sodden routines and unpleasant surprises, he could hardly have done better than handing down our present system. It is like a set of trapezoidal building blocks, with no vertical or horizontal surfaces, like a language in which the simplest thought demands ornate constructions, useless particles and lengthy circumlocutions. Unlike the more successful patterns of language and science, which enable us to face experience boldly or at least level-headedly, our system of temporal calculation silently and persistently encourages our terror of time. ... It is as though architects had to measure length in feet, width in meters and height in ells; as though basic instruction manuals demanded a knowledge of five different languages. It is no wonder then that we often look into our own immediate past or future, last Tuesday or a week from Sunday, with feelings of helpless confusion. ... --Robert Grudin, 'Time and the Art of Living'.
- jiveturkey 4y agoNice article. Of course it's more of a human interest piece, but still, too bad they don't talk about PTP at all.