There was effectively no firewall at UNC-CH at the time (something something academic freedom something something), and the Stat Solaris machines were not being regularly patched. Uninvited guests had infested them, and it appeared the most likely entry point was sendmail - at the time, it was the most notorious vulnerability on the internet. Since my preference to wipe and reload was unacceptable - too much downtime and too many billable hours - the obvious thing to do was update sendmail. The rest is history.
Thank you for the comment. It was delightful to hear your take on the (mildly apocryphal, but highly enjoyable) tale.
Trey Harris also on HN [0].
I'm currently at the very early stages of building a science museum and will eventually try to incorporate this story into an exhibit about light speed. This along with "Nanoseconds", foot long pieces of wire like what Grace Hopper handed out, can truly help to bring this topic to life.
I'm also attempting to use this as the basis for a blockchain based "proof of proximity" in which a very high number of round trip encryptions of the previous blocks hash are stored in a bitcoin block. The number of round trips would be high enough that devices even a few hundred feet apart couldn't complete the task before the next block.
It's not that bad, these things happen.
It makes an interesting story though
https://www.ibiblio.org/harris/500milemail.html
FAQ about the story:
https://www.ibiblio.org/harris/500milemail-faq.html
Past submissions:
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
(It seems I can’t find a search query which includes both urls)
This could have happened a million times where the story was a lot less interesting:
"Hey, I'm having weird intermittent problems sending email."
"Hmm, we're using the wrong version of Sendmail. All fixed, case closed."
It seems that GNU units at some point added support for several non-linear units, which may have prompted them to rethink their syntax.
$ units
Currency exchange rates from FloatRates (USD base) on 2020-05-12
$ sudo units_cur
$ units
Currency exchange rates from FloatRates (USD base) on 2020-07-09
You have: 10 franc
You want: dollar
conformability error
1.5244902 euro
1 usdollar
You have: 10 franc
You want: euro
* 1.5244902
/ 0.655957 $ units
Currency exchange rates from FloatRates (USD base) on 2019-06-05 3 millilightyears / 365 / 86400
You have: mph
You want: kph
* 1.609344
/ 0.62137119 alias units='units --verbose
You have: mph
You want: kph
mph = 1.609344 kph
mph = (1 / 0.62137119) kphWhen I flush my toilet my computer reboots: http://www.techtales.com/tftechs.php?m=199712#66 (the first story on the page)
If I buy vanilla ice-cream my car wont start: http://www.netscrap.com/netscrap_detail.cfm?scrap_id=501
A specific cargo routing crashes system: https://www.jakepoz.com/debugging-behind-the-iron-curtain/
Tape-drive failure only within large print jobs: http://patrickthomson.tumblr.com/post/2499755681/the-best-de...
Interplanetary debugging with the Mars Rover: https://www.eetimes.com/the-trouble-with-rover-is-revealed/#
The guy was working on an optical sensor in a light-tight lab. Every morning, he came in, calibrated the sensor, and performed measurements. All morning, it held calibration with negligible drift. But when he came back from lunch, each time, the calibration had drifted off.
Could it be related to the time of day? He tried taking his lunch an hour earlier and an hour later. Each time, the calibration was rock solid until right after lunch.
In spite of protocol, he tried eating lunch in the lab, no one else in or out. Before lunch: good calibration. After lunch: bad calibration.
He tried not eating lunch at all. That day, the calibration held all day.
How could an optical sensor have any concept of whether its user had eaten lunch? It turned out, it only had to do with the lunch box. The sensor was fiber coupled, and it was sensitive to changes in transmission losses generated by changes to local radii of the patch chord. Every morning, the grad student set his lunch box down on the lab bench, nudging the fiber into some path. After eating, he’d replace his lunch box on the bench, nudging the fiber into a different path.
After that, the fiber was secured with fixed conduit, and lunch boxes no longer entered the lab.
https://news.ycombinator.com/item?id=12778904
https://news.ycombinator.com/item?id=21578606
https://news.ycombinator.com/item?id=16384158
https://news.ycombinator.com/item?id=16285093
https://news.ycombinator.com/item?id=12997568
https://news.ycombinator.com/item?id=3802458
https://news.ycombinator.com/item?id=123489
https://news.ycombinator.com/item?id=385068
https://news.ycombinator.com/item?id=2701063
https://news.ycombinator.com/item?id=14676835
https://news.ycombinator.com/item?id=1293652
https://news.ycombinator.com/item?id=10305377
https://news.ycombinator.com/item?id=12126564
https://news.ycombinator.com/item?id=6296201
https://news.ycombinator.com/item?id=3427263
https://news.ycombinator.com/item?id=17591084
https://news.ycombinator.com/item?id=8176458
https://news.ycombinator.com/item?id=3114391
https://news.ycombinator.com/item?id=19321973
https://news.ycombinator.com/item?id=13667317
https://news.ycombinator.com/item?id=13082438
https://news.ycombinator.com/item?id=10734108
https://news.ycombinator.com/item?id=22065142
https://news.ycombinator.com/item?id=19749556
https://news.ycombinator.com/item?id=9081869
2008 https://news.ycombinator.com/item?id=123489
2008 https://news.ycombinator.com/item?id=385068
2010 https://news.ycombinator.com/item?id=1293652
2011 https://news.ycombinator.com/item?id=2701063
HN doesn't have a rule that there should only be one canonical submission for every individual link or topic. That you thought your comment would contribute anything leads me to believe that you aren't aware of that.
But ... isn't the speed of light through fiber actually like 2/3 of the speed of light in a vacuum? And that fiber isn't going to be laid out in a straight line exactly to the destination. So I think really there must have been a fair bit of uncertainty around that ~3ms to abort a connection.
It's easy to forget that, even though transmissions still travel at near lightspeed, it still takes more than an instant to reach its destination, even digitally. I should keep this in mind, I think.
This one and the microsoft bedlam one are some of my favorites.
As a hobbyist sound engineer, usually regular cables are the first I check, but maybe I should extend that to fibre?
Interesting error nevertheless, and honestly, checking fibre cabling for those kind of errors would probably be a bit lower on my list, unless I saw a lot of tranciever errors.
I'm certain it will continue to be reposted to this website until ceases operations or the heat death of the universe whichever comes first.
I also would like help understanding what $ units gives? The command looks to be "units", but where do the numbers he entered in come from? I would appreciate this extra context.
Here is a good explanation: https://blog.stackpath.com/point-of-presence/
The FAQ[0] mentions:
> units on SunOS doesn't know about "millilightseconds."
> Yes. So? I used to populate my units.dat file with tons of extra prefixes and units. And actually, I think I was using AIX to run units; I don't know if it knew about millilightseconds. Take a look at the units.dat shipped with Linux these days. It definitely knows about millilightseconds.
I tried locate for units.dat but couldn't find it. Anyone knows where is it? Not keen on running a system-wide find.
ubuntu: /usr/share/units, after `apt-get install -y units`
FYI units on OS X doesn't recognize millilightseconds, but you can do this:
You have: 3 lightyears / 365 / 24 / 60 / 60 / 1000
You want: miles
* 559.21802
/ 0.0017882113 % units
586 units, 56 prefixes
You have: 3 lightyear*millisec/year
You want: mile
* 558.84719
/ 0.0017893979
/usr/share/misc/units.libThere was an odd situation where some of the systems were unable to make connections to other systems ....some largish distance away. It was fairly variable, but some systems were almost always unreachable, and some were occasionally reachable.
Long investigation, but in summary, this happened because the default packet TTL was, for some reason, set to a fairly low value in a minor kernel update. I simply increased that number in the kernel, recompiled, and all of the problems went away.
Latte's in 1994? In North Carolina? No way. Maybe on the West Coast, but I moved to Cali in 1989 and they were a rarity until the mid-late 90's. There were only 425 starbucks in the US in 1994 (from their site). The "fancy coffee" craze was just a blip on the radar in the mid 90's but gaining momentum.
;-)
Friends premiered in 1994, with The Central Perk being a major set piece of the show. I mean, yeah, its New York City and not North Carolina, but college towns anywhere are going to be early in trends.
A latte in 1994 seems plausible to me. I remember getting them from a Gloria Jeans in my local suburban mall around 1990 or so.
You're not wrong about the shape of the trajectory, but all throughout the 80s the coffee shop/latte trend was slowly building steam (heh) before it went hockey stick in the mid-90s.
So yeah, lattes in ‘94 in a major college town seems totally plausible.
Definitely possible. Chapel Hill isn't like the rest of North Carolina, so I'd expect something like that to appear here before other parts of the state. And I remember the Books-a-Million in Wilmington started adding a cafe / starbucks-like area for "fancy coffee" about 1996 or so. I have no problem believing there were shops serving latte's in Chapel Hill during the era this story is described as happening in. And to be fair, the author even says in the FAQ that he's not sure about the exact date(s). It could have been as late as 1997.
> My guess, from the office I remember being in, the coworkers I remember speaking about this to, and some other such irrelevant but timely details, place it somewhere between 1994 and 1997.
We drank lattes in Louisiana in the 80's. Time to upgrade your stereotypes.