[HN Gopher] Got called to a professor's office after a complaint... ___________________________________________________________________ Got called to a professor's office after a complaint his SPARC4 was running slow Author : luu Score : 781 points Date : 2023-07-25 03:00 UTC (20 hours ago) (HTM) web link (infosec.exchange) (TXT) w3m dump (infosec.exchange) | gnoack wrote: | In the mid-2000ds, there eventually came a time when the xlock | (Ex-lock) screen locker disappeared from the last university | workstations that still had it. People routinely got puzzled when | they could not run it. It was a fun prank to tell them that Ex- | Cee-lock was the replacement for it (which would, of course, run | the clock application). :) | mcv wrote: | Xlocking workstations became a problem at our university. | People would claim a workstation, lock it, go do something else | (lunch, lecture) and then come back to their reserved | workstation. So the admins added a button that you could log | someone out if the screen had been locked for more than half an | hour. | | They didn't want to ban xlock because they cared about | security. | yomlica8 wrote: | In high school I'd reserve workstations for my friends by | unplugging the keyboard. The PC would fail to boot with | "Keyboard not found, press F1 to continue" which was enough | to get it designated broken and avoided. | LoganDark wrote: | > Keyboard not found, press F1 to continue | | I don't know why this is so funny. Probably because it's a | catch-22 since you need a keyboard anyway in order to press | F1. | alexjm wrote: | It's a poorly worded message, but the idea is that you | press F1 after plugging in (or otherwise fixing) the | keyboard. | jweather wrote: | I did this unintentionally in college once by switching the | keyboard layout to Dvorak, which for some reason persisted | across logins. I came back later that day to the same lab | and the station I had been using was marked "Out of Order". | Huh, that's weird. Sat down at the station next to it. Next | day both of them were marked "Out of Order". Oh, huh. Is | there something weird with the keyboard? I might know what | happened... | dspillett wrote: | _> So the admins added a button that you could log someone | out if the screen had been locked for more than half an | hour._ | | In our CS labs the PCs re-imaged themselves on boot0, from a | choice of OS images1, so you didn't have to worry about | causing corruption of the machine by just power-cycling it to | get around the locked status. This meant that locking a | workstation to reserve it didn't work. | | My workaround to that2 was to set the wallpaper which | displayed behind the unlock prompt to an image of a | bluescreen indicating a hardware error and move the window | containing the lock prompt to the for bottom right of the | screen, so it was just a single pixel and not easily noticed. | Hey presto: a locked machine that no one wanted to claim by | restarting because it looked faulty. Obviously anyone with | half a brain watching me unlock the machine a short while | later would immediately work out the trick, so the knowledge | spread soon enough and the ruse stopped being as effective. | It was very effective for a while. | | -- | | [0] from the same shared network drive, which was initially a | problem (this was the first year that lab had been in | operation) if several machines re-imaged at the same time as | head thrashing caused IO throughout to fall through the | floor. Later revisions of the setup helped by tweaking cache | settings, and giving the server more RAM, so that the second | and subsequent read of an image in a given period would come | from cache, also the images were compressed for the same | reason and also to reduce the second bottleneck: the glut of | traffic through the server's single 100mbit NIC. | | [1] usually just Windows NT and the local Linux build, but | sometimes other options were present | | [2] which I used very occasionally, partly to not be a dick | but mainly so as to not give the game away to quickly | Trixter wrote: | In high school in 1988, a friend and I discovered a vulnerability | in the netware deployment of 30 IBM PS/2 Model 30-286s in our | brand new computer lab that allowed us to insert programs into | the autoexec netboot sequence. Prior to that, we'd been hacking | on the (brand new at the time) VGA registers and figured out how | to switch from 80x25 text mode to 320x200 256-color graphics mode | with no flicker or glitches, as both modes have a refresh rate of | 70Hz. So he created a TSR that preloaded a digitized picture of a | clown face (a popular upload on BBSes at the time) into | A000:0000, and after about 4 minutes, it would display the clown | face for a few frames and then immediately switch back to | whatever the user was working on. We gave ourselves away because | we couldn't stop laughing in the corner of the room watching all | the students get very confused/horrified looks. One bonus was the | comic timing of a student calling the instructor over, having him | stare at the screen for 3+ minutes, turn away, then have the | clown face flash when he wasn't looking. | | My friend's name was Brian, one of the smartest people I've had | the privilege of knowing. Ten years later, we created | mobygames.com. | LorenPechtel wrote: | My gag was a bird chirp that would play every so often-- | typically minutes between chirps. There were several random | numbers that went into making the chirp so it would be | different every time and every noise it made would be shifting | frequency, never a moment of a fixed tone (back when speakers | usually just went BEEP.) Leave it running on a machine that | wasn't being used... | daly wrote: | IBM 370 mainframe, 80+ programmers, running VM/370 which creates | virtual machines, one for each programmer. I'm one of two systems | programmers with "superuser" privs. | | In the virtual machine you normally ran CMS but you could run | anything. Some machines ran MVS. | | To direct a command to the virtual machine itself you would | prefix the command with a special character which by default was | # but any chosen character could be the magic prefix. So #cp ... | would be a command to the virtual machine. | | Bored one day I wondered if a virtual machine could run VM | itself, on the "second level". I booted it up, changed the prefix | character to ! (so, !cp). I could create new virtual machines | inside this new VM. | | So, could a second level virtual machine run VM? I booted it up | on the "third level", changed the prefix to @ (so, @cp)... | | I got 8 levels deep. So, yes, VM could run VM, could run VM, | could run VM... etc. | | Game over. Time to start shutting down these embedded levels. | | Out of habit I typed "#cp shutdown" ... and it did. The REAL VM | on the REAL machine shut down. Panic run to the machine room to | push the start button on the console. | | Of course the system keeps a log ... and the other systems | programmer showed up at my door ... and said "don't do that | again". | | Fun times. | rwmj wrote: | I wrote this for abusing qemu in the same way: | http://git.annexia.org/?p=supernested.git;a=summary | Neil44 wrote: | When I worked in IT at a big company we had a fake screensaver | that emulated a blue screen and boot loop situation. Nobody ever | thought to press a key or move the mouse which would have cleared | it, they would always go for a power cycle followed by lots of | hilarious troubleshooting, before it happened again and again. | Good times. | 1vuio0pswjnm7 wrote: | For text-only browser users: | | https://infosec.exchange/@paco/110772422266480371/embed | raverbashing wrote: | You mean for the poor people that don't have an X capable | terminal and only have a VT100 | hulitu wrote: | I don't even have a VT100. I have an Android phone. | EgregiousCube wrote: | Sort of a meta-comment about infosec.exchange, so I expect a few | downvotes, but while this was a funny dad joke it took more | scanning and reading than it was worth. Mastodon UI's are very | dated despite being new. I miss interdepartmental unix pranks! | rblatz wrote: | I tried to read it and it was unusable. I had to turn on reader | mode to make it at all usable. | o1y32 wrote: | This thing has a side bar even on a mobile device which shrinks | the width of the text even more. The text is very difficult to | read. You have to acknowledge that Twitter is a carefully | designed and mature product at least in terms of UX. | devin wrote: | I wrote some code to run on the office computer that we used to | stream music from. At a random time every 24-48 hours, it would | turn its volume up and say "I love you" using the Mac OS whisper | voice. | guerrilla wrote: | Ahh, I miss AppleScript and those voices... | dzdt wrote: | A grad school prank one of my friends pulled on another: | echo sleep -1 >> .login | | was appended to the .login file of the victims account. The | victim stepped away from the terminal briefly leaving themselves | logged in allowing the prankster to make the addition. It was | days later with over 20 sleep statements appended before it was | apparent that something was uniquely wrong with that student's | login. Day after day the victim grew increasingly frustrated with | the slower and slower times from initial login to active | terminal. Finally when it was getting unbearable the prank was | discovered. | kwantam wrote: | Came here to reminisce about the same trick :) | | After a while we decided that adding one second per login was | too subtle... echo "echo sleep 1 >> ~/.login" | >> ~/.login | NoZebra120vClip wrote: | Good news! Now that "sleep" supports fractional seconds, you | could ratchet up the suspense verrry slllowly... | fit2rule wrote: | [dead] | awiesenhofer wrote: | And here I thought for a second this would be a story about a | professor who still uses an old SparcStation today... | heelix wrote: | Back in the day when a 4x CD-ROM burner was a luxury, we got a | phone call from a customer we shipped a CD to. Would not read. | Did a second burn at 1x speeds, tested on several machines, and | mailed out the disk. Would not read. Burned a third and tried on | every unique setup we could find on the most premium disk we | could buy. Would not read. | | I drove out to do the manual install a stack of media in hand. | Got to the customer site - and watched in horror as they put the | CD-ROM in the 5.25" floppy drive. It fits. | datenwolf wrote: | If you really, really want to ruin an X11 session, I got you | covered: | | https://git.datenwolf.net/codesamples/tree/samples/X11/x11at... | g051051 wrote: | Someone at work played this prank on a business analyst and | almost got fired. It was the early 90's, and we were a shop | running HP/UX on Apollo workstations. She was a SME for the | application we were developing, but was otherwise non-technical. | He and her were friends, so one day he fired up xroach on her | system. When she moved a window she absolutely freaked out, and | wanted the guy fired. He kept his job, but I don't think they | were friends after that. | NoZebra120vClip wrote: | Plenty of people in this thread with Apollos in their past. We | had no fun on the Apollos in college; they ran DOMAIN/OS, I | programmed the 68xxx assembly and I got out of there. | | I did all my mischief on the Unix machines: 3B2s with dumb | terminals, and diskless SPARCstation SLCs. | ggm wrote: | In some ways it was a sw bug: the roaches should have been more | apparent, not simply breeding. | maxbond wrote: | Friends don't let friends merge code that consumes resources | without bounds. | silisili wrote: | True. In reality once they started crowding they'd have started | scrambling in the open. | pmontra wrote: | I remember a variant of xroaches: it had crawling babies with | diapers. Maybe they wouldn't multiply under windows but they | could be just a different bitmap with the same algorithm. | rwmj wrote: | xneko was the best one. | n6h6 wrote: | I looked it up, and aww :) | | https://en.wikipedia.org/wiki/Neko_(software) | | Unlike many of the things people talk about on this website | that I didn't experience growing up, I actually did download | this on Windows Vista once. It might have been a version with | malware, but I don't remember. | ragebol wrote: | Wanted to install xroach on my Ubuntu box, but no apt package is | available. | | There is xroachng though [0], created by: Willem_ _vermin_ :-) | | [0] https://sourceforge.net/projects/xroachng/ | codewiz wrote: | No Wayland version yet? | pavon wrote: | From what I understand this would have to be built into the | compositor, as it is the only process that knows the | positions of all the windows. | alexeiz wrote: | It's available in openSUSE repos. Just saying... | lordgrenville wrote: | Looks pretty easy to compile | https://github.com/interkosmos/xroach | ragebol wrote: | Yep, couldn't be easier. It's been running on my box since I | left my comment. No bugs observed yet, maybe they are hiding | too well | Gordonjcp wrote: | [dead] | p0d wrote: | Must be 20 years ago as Google was a thing and we had a split | monitor and kvm with the one computer in the school IT classroom. | | My colleague types hello into the Google search box from the next | room. The student then typed who's this? Colleague types, Jimi | Hendrix...student turns computer off at the plug :-) | nathell wrote: | Ah, the golden student days of yore. | | Mine were in the early 2000s. Back then, the computers at the lab | at my uni were not very powerful, so people would do work at a | Linux console, saving themselves the hassle of running a bulky X | session. | | Some time around 2001 I read the console_ioctl(4) manpage and | found it replete with prank possibilities. I wrote little | programs that would flip the console font so that all the | characters were upside down; or swap capital letters with small | letters, again by way of manipulating the font; or flash patterns | on the keyboard LEDs; or fade to black and back by manipulating | the palette. | | I then added a server component so that I could leave it running | at an innocuously-looking terminal, wait for a victim, fire up | these effects remotely from another box in the same room, and | watch what happens. Fortunately, I soon discovered that the | coding part was more fun than the watching-people-slip part, so I | gave up on the latter. | | Another prank I used to do was simulate a successful root login | on these terminals by just typing in what would be printed, | including the motd, at the getty login prompt, simulating | newlines with tabs/spaces (and never ever pressing RET), ending | in `[root@mailhost root]# `. Then, again, step back and watch | what happens. Some people would curiously type in `whoami` and be | puzzled why they got a password prompt; some would step back in | terror without touching anything, switch terminals and email the | sysadmin. | 0x6c6f6c wrote: | I wish I'd had Linux systems. I was doing the same type of | thing with Windows networks since you could effectively run any | program as any user with task scheduling so long as they were | logged into the system. Pair that with active directory and you | have user info. So knowing who was where, open iexplorer at | certain site, innocuous word doc, etc. The most malicious case | was an automated logout batch script. | | People eventually caught on to the approach and tried to | replicate the remote execution but executing as themselves | instead of that user so when the IT admins came around there | was a very obvious trail to who had been running it. I stopped | playing around but eventually IT then SWE became my profession. | I sometimes wonder how it'd have gone if I'd been reprimanded | though. | xolve wrote: | This certainly sounds fun! This is how people realise coding is | immensely fun and impactful when you are involved in the | results :) | lizknope wrote: | The xroach man page has some options that not everyone knows | about | | Turn on -squish and set the -rgc (roach gut color) and you can | make your screen look disgusting! It was great in college in the | mid 1990's | | Then there were the jokes about "SEE ALSO" for xroachmotel and | xddt | | https://manpages.opensuse.org/Tumbleweed/xroach/xroach.1x.en... | | -rc roach_color Use the given string as the color for the bugs | instead of the default "black". | | -speed roach_speed Use the given speed for the insects instead of | the default 1.0. For example, in winter the speed should be set | to 0.1. In summer, 2.0 might be about right. | | -roaches num_roaches This is the number of the little critters. | Default is 10. | | -squish Enables roach squishing. Point and shoot with any mouse | button. | | -rgc roach_gut_color Sets color of the guts that spill out of | squished roaches. We recommend yellowgreen. | | SEE ALSO | | xroachmotel(1), xddt(1) | password4321 wrote: | In my case a professor took a lab PC for their office, but the | script to shutdown all the lab computers every night wasn't | updated... | frellus wrote: | The other trick, aside from xroach, we would play on professors | would be to take a screenshot of their desktop and re-display it | as their wallpaper, with windows opened and all. To see a | professor close an app window and still see it on the screen | (from behind where it was) and to try over and over futilely to | hit the "x" to close it on X Windows was a beautiful sight. | | It wasn't _our_ fault professors typically ran "xhosts +" in | order to make their lives easier. | | Source: my 25 year-ago mischievous self ... Sparc. Miss those | days. | m463 wrote: | I remember lots of things like this, from the sunos days. | | There was a program that would sort of melt your screen. | | There was another one that would animate a little character at | the bottom who would then push your desktop off the side of the | screen. | | and there was a way to take all the workstations in the group, | and play sounds on them. | | So (nearest I can vaguely recall): for i in | machine1 machine2 machine3 ... do rsh $i "play | applause.au &" done | | sunos came with sound files for laughter and applause, and it was | amusing to have all the machines in the group laugh or applaud | like a crowd. | | (well it was amusing the first few times anyway...) | lakkal wrote: | We had some Apollo Domain machines at school which could also | run similar programs - I remember 'Crumble' and 'Melt' being | two of them. And you could run them on other peoples' display. | So we used to melt/crumble the screens of the engineering | students in the next lab over. 'We' in this case had admin | privileges, though, and only did it a couple of times. | AnimalMuppet wrote: | > There was a program that would sort of melt your screen. | | This existed for PCs, too. It was called "drip". When idle, | individual characters would "drip" down your screen like | raindrops, at random times, for random distances. | | Another one I remember was "drain". In the very early PC days, | you could add this program to the AUTOEXEC.BAT of an | unsuspecting victim's computer, so that it would run at | startup. It would start flashing "SYSTEM ERROR 0304-B" for a | moment, then add "Water detected in disk drive A:". Another | moment, then "Now draining", and it would play this gurgling | sound out of the speakers (as best you could, on the speakers | of the original PC). That would peter out, then "Now starting | spin dry cycle", and it would play this whining sound for a | bit, ramp that down, and then tell you that it was OK to use | the system now. | | In those days, there weren't "logins" to PCs. If you saw a PC | without the normal user present, you could do _anything_ to it. | Starwatcher2001 wrote: | I seem to recall that "Drain" spun up the motor on the floppy | drive to create the spin dry cycle. | AnimalMuppet wrote: | If I recall correctly, the drive light stayed on, the drive | was spinning, but the whine came from the speakers, and | moved to a higher pitch partway through. It also smoothly | ramped down in "RPM" (frequency) at the end, which is not a | thing that the floppies could do. | m463 wrote: | PCs always had better stuff. I remember (fondly?) the After | Dark Totally Twisted screensavers. | lizknope wrote: | If someone xhosted my machine I would run xmeltdown back to | their display. I wrote in another post in the thread about how | and why someone would xhost my machine. | | https://github.com/veltzer/xmeltdown | mcguire wrote: | Largely unrelated, but I was told once by a senior sysadmin | that I was never, ever to send an email with the Open Firmware | song attached to it. | | https://youtu.be/b8Wyvb9GotM | pjmlp wrote: | On our university lab, the main reason why most of the savy users | would have "xhost -" on their login scripts would be to avoid | being shown not so convenient images at the wrong times. | bluedino wrote: | Back in my MSP days I had a client report that their server was | slowing down after an hour. They would also use this "server" (a | tower computer in a back room) to adjust inventory, print | reports, etc, but after an hour of having used it, everything | would slow to a crawl. It was running databases and such that | other computers in the building accessed. | | Every time the server slowed down, someone would go back there | and restart the software, or reboot the whole computer, and it'd | be fine for another hour. | | Sure enough, after an hour, some fancy ass 3D screen saver came | on and pegged the CPU. It was some shareware thing that someone | downloaded because it looked cool. I ended up turning the | screensaver off and just set the monitor to go to sleep after 10 | minutes. | yjftsjthsd-h wrote: | It's funny how many stories from earlier times boil down to "it | wasn't meant to be malicious, just funny, but people didn't | realize that it would multiply that much or use so many | resources". See also: the morris worm (I mean, that arguably | _was_ designed as malware, but supposedly wasn 't supposed to be | nearly as bad as it was) | Reason077 wrote: | Guy is still running a SPARC4? In 2023? No wonder it's slow! | phs318u wrote: | Back in 1989 I worked as a one-man-IT-department for a bunch of | ex-academic economists doing econometric modelling on a Digital | VAX 11/750. This mini-computer was running VMS - a multi-user | operating system. All users had admin rights and each one thought | that they could make their models run faster by bumping up the | process priority as far as it could go - which of course | interfered with the realtime processes needed to manage the | effective running of the computer. Unsurprisingly, this had the | opposite effect to what they intended. When I discovered this was | what was happening, I revoked their privileges and after a system | restart, sanity was restored. I was thanked for finally making | the system work faster. | ycombinete wrote: | Great example of the economic principle _The Tragedy of the | Commons_ : | https://en.m.wikipedia.org/wiki/Tragedy_of_the_commons | ww520 wrote: | Economy is all about incentives and behaviors. Did they learn | any lessons from how they acted during the episode? And | hopefully published a whole bunch of papers from it? | jjp wrote: | Had exactly the same with a bunch of developers who could | change the queue priority on a mainframe for their own work. | They couldn't work out for themselves that if everybody set | their work to the highest priority it had no benefit to any of | them. Trying to educate them failed, so we revoked access. | darkclouds wrote: | > All users had admin rights and each one thought that they | could make their models run faster by bumping up the process | priority as far as it could go - which of course interfered | with the realtime processes needed to manage the effective | running of the computer | | It amazes me what the bios and OS or OS api's let you do, even | on modern devices. | LoganDark wrote: | > It amazes me what the bios and OS or OS api's let you do, | even on modern devices. | | Same, but not necessarily in a negative way. I like pushing | my hardware and software to the limits, becoming unable to | push those limits would be pretty disappointing. | Kon-Peki wrote: | I'm not sure anyone should call VMS "modern", but that's | beside the point ;) | | VMS has a very comprehensive system of quotas and limits, | so a "properly" configured system wouldn't suffer those | issues. | | And furthermore, VMS isn't intended to be used | "interactively" as such. You should be submitting work to | the built-in batch queues - each with various attributes | that can include the priority level. This allows the system | to intelligently manage work based on a comprehensive view | of the entire system - something a single user in a multi- | user system can't have. If you like pushing a multi-user | system to its limits, you'd be impressed with what VMS | could do even way back in the 1990s. | infostud wrote: | I remember going along to a VAX/VMS System Administration | workshop. Another bloke and I did a prank where we substituted | text of the text editor that would produce blinking "Working" | if it got busy. We substituted "or" with "an". The workshop | coordinator caught us because we forgot to do something I can't | remember and a login was tied to the change in the executable. | | Happy System Administrator's Day! | latchkey wrote: | Oh, my first internet access was through one of those in 1991 | at college! Found a cool exploit that let me anonymously | broadcast messages to anyone. Sure freaked out a lot of people. | Was fun cause you'd get to see the effects of your action in | real time because it was a bunch of people in the same room on | shared terminals. | pdntspa wrote: | Reminds me of WinPopup spam on Windows 95 | cheese_van wrote: | Around '84 doing seismic data. We just got a terminal in the | office that would allow you to monitor the jobs running on | the IBM mainframes downstairs. Completely new tech to all of | us. It had a command line message capability. Because it was | quite easy to send to all instead of just your recipient, one | marriage ended rather suddenly. Seeing the effects of your | actions with new tech in real time indeed. | sokoloff wrote: | Working at a hedge fund with multiple locations, the | founder insisted that mail to "staff" would reach everyone | at the local office and mail to "all" would reach everyone | (in all offices). | | One afternoon (in the middle of the trading day), we got a | weird email with an empty body and a bunch of nonsense | email addresses. Turns out some poor trader wrote an online | dating email, but pasted/wrote the mail in the cc line, | resulting in all of us learning that he thought "you don't | seem like all the other girls", which was sent to you@, | don't@, seem@, and the dreaded all@. | joshjje wrote: | Nice, reminds me of my high school computer lab. I wrote a | trojan horse in VB6 and distributed it among the lab PCs | somehow, then from mine I would open and close peoples CD | trays, turn their monitor off, send them to... questionable | websites where they would swear it wasn't them! Haha, good | times. | FractalParadigm wrote: | A friend and I were able to phish passwords from nearly the | entire school we went to with VB6 - the school (board) used | active directory for logins on a shoddy network where some | switches would often just drop all traffic to a random port | for any length of time, meaning a PC would lose connection | to the AD server at random. The kicker was that attempting | a login after the connection was dropped greeted you with a | "could not connect to //SCHOOL_BOARD//SCHOOL_NAME/PC_NAME" | to which the solution was reboot the PC and it would work | again (99% of the time, anyways). The other kicker was the | background image and login domain were the same for every | single computer at a single school. We exploited this; we | created a full-screen/un-exitable UI with the same | background image behind a form simulating the normal login | screen. We would first login to our own account and run the | program (there were no login limits either), at which point | someone else later through the day would sit down and try | to login. The credentials that got typed in were added to a | .txt in my own user folder before the user rebooted the | "non-functional" system. Of all the dumb shit we did, | that's probably the only thing we never got caught doing, | and probably because we never did anything nefarious with | them. | taneq wrote: | "Cool exploit"? Like net send? :) | KnobbleMcKnees wrote: | I was banned from the school computer suites several times | for (ab)using net send. Good times. | adenner wrote: | I remember someone getting a bit wild with their netsend | and accidentally spamming the entire school district, | including the administration. We also found out that you | could DoS your instructor with enough messages. | myself248 wrote: | On our high-school network, the Guest account had NET | SEND privileges. It was somehow less chaotic than one | might expect. | | We had a single shared T1 pipe for the whole district. | Which was enough for email and stuff, but when web | browsers got popular, it was suddenly woefully | inadequate. | | So I figured out I could NET SEND * SERVER ROOM POWER | FAILURE - 9 MINUTES OF BATTERY REMAIN - SAVE YOUR WORK | AND LOG OUT and after a flurry of traffic, the network | fell to nearly-idle. I could max out the T1 with whatever | I needed to do for a few minutes, then NET SEND * SERVER | ROOM POWER RESTORED and nobody would be the wiser. | | The admin did go check on the "flaky UPS" a few times | before looking closely at the message. Had a good laugh | and told me not to use it too often. | fullstop wrote: | I was able to use samba to generate these messages such | that they looked like they came from other users in the | lab. We had a lot of fun with that. | gadders wrote: | I remember in the mid to late 90's when you could get spam | from outside of your network via net send. Happy days... | jethro_tell wrote: | Wall | em-bee wrote: | the key "feature" of the exploit was the ability to send | messages anonymously. the unix commands "write" and "wall" | allow you to send a message to any users terminal. | | apparently "wall" has a switch "-n" to hide the sender | | https://unix.stackexchange.com/questions/99460/sending- | messa... | | for windows there was "net send" which could be exploited | by a tool called NetSendFaker, but this was 1991, so i | doubt that already existed. | idontwantthis wrote: | If a group of economists can't coordinate their behavior to | prevent tragedy of the commons then they should rethink their | career and life choices. | zer8k wrote: | A group of economists couldn't coordinate splitting a bill at | Applebee's. | yabbs wrote: | Applebee's... Does not compute. | hgomersall wrote: | On the contrary, it was a rational attempt to limit their | ability to break things. | dghughes wrote: | That reminds me of a story from a guy I worked with. | | I'm not sure where he worked but it involved a queue of people. | He said someone asked him if they could be given priority for | their problem to be looked at before others in the queue. In | other words jump to the head of the queue. | | He said "Sure!" to the surprise of the person asking "But you | do realize I will do that for anyone else who asks the same | thing?" | | So they person chose to remain in their place in line. | shagie wrote: | There was a system that a bunch of students administered (I was | one of the students at the time). We would occasionally prank | each other. On this DEC station where memory was scarce, one | guy ran emacs. | | Another guy wrote a program that forked 1000 copies of itself, | nice itself to 19, did a sleep(0) and then exit. As soon as it | got _any_ cpu time, it would exit, but it never would as long | as emacs was running. Meanwhile, the load (as displayed by | xload) became a solid black box. | | So the emacs guy would run 'ps -ef | grep procname | xargs | kill' as root. | | This meant that it had to get some cpu time to handle the kill, | which took longer than a sleep(0) and was largely ineffective. | | The second time this prank was done, the process was named | 'ema'... which promptly also killed all instances of emacs too. | | The third time this prank was done, the process was named 'et'. | This happened to have also matched /etc/initd and the machine | rebooted rather suddenly. | arethuza wrote: | We used to play pranks on each other such as logging into the | NeWS server on a colleagues machine and manually setting a | small rotation in the transformation matrix for a terminal | window that someone was typing in.... | | NeWS had an interactive PostScript shell and almost no | security so this kind of mucking about was trivial... | jfk13 wrote: | Ah, good times.... we used to do similar things across the | HP Apollo workstations at the place where a friend of mine | worked (and I unofficially "borrowed" computing facilities | for a project of my own -- though I did also contribute a | substantial speed optimization to their main product, so | nobody seemed to mind). | gcr wrote: | For april fools' day, on my first job as a troublesome | ~16-year-old administering our university lab's firewall | (academia was a different land when it comes to trust), I | set up some automatic network-wide substring replacement | filters for incoming HTTP responses to replace `<body` with | something like `<body style="transform: rotate(0.1deg);"`. | This was in the time before HTTPS was ubiquitous, so it | worked on most websites. | | Unfortunately, it broke some pages that lab users needed | for school. I later learned one colleague wasn't able to | complete a homework assignment because of my prank. | crest wrote: | The joy of running Upside-Down-Ternet as transparent | proxy on April Fool's day. | Aperocky wrote: | "occasionally" | shagie wrote: | Occasionally. It wasn't a daily, or even weekly occurrence. | But, in all honesty those pranks were some of the things | that helped my early sysadmin experience. | | When you have nice, well behaved users you'll not have | problems that need solving. When things go awry - that's | when you'll need to solve problems... sometimes even | without pranks. | | Before we had yp set up on the machines, we just copied the | password file between them with a note "make sure you | change your password on foo" since that was the one we | regarded as authoritative and would copy that to bar. | | One time, while adding a person to the /etc/groups file for | write access to the web server, someone did rcp /etc/groups | bar:/etc/password (I suspect it was muscle memory) and, | well, now bar was unhappy and wouldn't let anyone log in... | or even su to root to fix it. Found someone who had an open | terminal and had them do a while 1 sync... and then powered | the machine down and brought it back up. It wasn't happy, | so started up in single user mode. Just needed to get the | password file in there... but the terminal was 300h which | didn't have a proper termcap entry for vi or emacs to work. | I was a mudder and knew how to use ed... so ed | /etc/password and then the contents of the minimal password | file were dictated to me. When done, we got it back up and | then copied the password and groups files to the proper | spots. | | Another time (and this was a prank), someone left | themselves logged in and someone else created a directory | path that was about 3000 characters long. /user/jsmith/I/wi | ll/not/leave/myself/logged/in/I/will/not/leave/myself/logge | d/in/ ... The problem with this is that `rm -rf` won't | handle paths longer than 2048 characters long. So it didn't | get removed "I'll do it later." You know what else doesn't | like paths longer than 2048 characters long? fsck. So when | the machine was rebooted/crashed at some point, the root | volume (yea, user directories were on the root volume) | failed to fsck... and failed to mount. Stuck in single user | mode with the backup partition and reading the man pages | for mount on the other machine we found how to force a | mount without fsck and then had the guy who did the | extremely long path fix it (and promise not to do it again) | and got machines working. | schoen wrote: | Somehow I've never considered what will happen on Unix if pid | 1 exits! | | Even though I'm pretty sure I've run with init=/bin/sh and | then typed "exit" at some point in my single-user session, I | have absolutely no recollection of the results. I should try | it on a few OSes and see! | suid wrote: | If PID 1 exits, the system usually panics immediately and | restarts. | rzzzt wrote: | "Attempted to kill init!" https://github.com/torvalds/lin | ux/blob/0b5547c51827e053cc754... | rollcat wrote: | "...and that's why we have to put half a million lines of | C in PID 1" | NikkiA wrote: | i'm reasonably sure that kill -1 1 used to be a canonical | way to `halt` | mcguire wrote: | I used to work with a long-time AIX kernel developer. His | method of shutting off his machine was "sync; sync; kill | -9 1". | | Of course, his method of preparing to move offices (a | common occurrence at IBM) was to | | 1. Take his (RS-6000) workstation home with him the night | of the move. | | 2. Otherwise, just lock his desk. | | He didn't have anything in his office but his chair, | desk, and workstation. | olddustytrail wrote: | I'm pretty sure psdoom warns you against killing init | LorenPechtel wrote: | I had something of the opposite experience. | | Digging into the manuals I figured out how to launch the | compiler as a background process so I could still have a | working system while waiting for it. Brought the whole | classroom to a halt. | | More digging revealed that the background priority was set well | above user priority. AFIAK no malice involved, just someone who | didn't know how to set the system up and left that landmine for | me to find. | havnagiggle wrote: | A bunch of economists couldn't play nice? | quickthrower2 wrote: | Behaving like perfectly rational actors, of course. | eru wrote: | That's like complaining that real world physicists don't | behave like frictionless spheres in a vacuum. | dtech wrote: | But they were, economic rational actors behave in their | own self-interest | jychang wrote: | Getting his software stuck and then kicked off the | computer is his self interest? | Dylan16807 wrote: | Wow, you annoyed someone enough to get your comment hidden, | impressive. | bstpierre wrote: | In 1993 my freshman CS class was taught in scheme. All of our | assignments had to be developed and tested on some shared | Digital machine running Ultrix. The scheme interpreter was kind | of slow to start, especially when there were 20+ users logged | in. Helpfully, our TA taught us how to ctrl-z to suspend the | interpreter, then edit our program in vi, and then "fg" to get | back into the interpreter. | | Unfortunately the fg part of the equation was lost on about 2/3 | of our class... after editing they would start another scheme | instance! I recall being in the terminal lab the night one of | our first assignments was due, and the machine slowed to an | absolute crawl. Can't remember exactly how it was resolved but | I do recall being taught how to look for classmates running two | or more instances of scheme to remind them about fg. (Also not | helpful to machine load: "solutions" to the 8 queens problem | with infinite recursion. The real lesson here was, in later | years, to not be logged in on nights when CS 401 had | assignments due.) | gte525u wrote: | I had a similar story with a friend in college in the 2000's. | He would always hit Ctrl-z'd to "close" emacs when logged | into the server which would've been fine if he wasn't using | screen or tmux as well. At some point, he was using a | ridiculous amount of RAM on the server and the admins | suspended his login to force him to come in. | grepfru_it wrote: | Once upon a time, we had several Sun Enterprise 450s that my | college used to teach Oracle to students. It was well | underutilized and the hit game Quake had come out. Of course we, | the IT support staff, ran a Quake server and invited all of our | friends to play on it. Imagine our surprise when one of our | professors we support came into our office and said "Hey our | Oracle instance is very slow, can you guys take a look at it?". | Whoops, we shutdown the quake server and he later sent an email | "I don't know what magic you guys did, but the performance is | amazing!". | | Another fun one, not targeted at professors, but at our student | compute lab. We had a lab of 25 Sparc Ultra 60s that was pretty | well utilized. Well one day, before I became a sysadmin, I was | thinking to myself "all of these servers are rsh enabled, what if | I logged into all of them". So I wrote a script that would cut up | an AU file (sun's audio format) into tiny parts and then wrote a | program that would synchronize with each other and play a | different part out of a different workstation. I vividly remember | playing a screaming sound in a ring around the entire room at a | low volume before playing the entire sound out of the three | middle workstations at full volume a few seconds later. The lab | was full. At least 15 people immediately noped out. I was sitting | in the back cracking up. | | Another time the sysadmins of the same computer lab left rwalld | running. So I sent an rwall "The system will shutdown in 5 | minutes" or whatever the shutdown message was. The professor at | the time got angry "they always do this, they perform maintenance | whenever the g.d. please" and he stormed out of the room. | Suddenly the professor and an angry IT administrator was peering | in the door and pointing at me. They threatened to revoke all of | my access which would cause me to fail out. I just shrugged, I | knew what they were up against and instead asked to work for | them. The anger turned to surprise and I worked there for almost | 6 years before leaving for greener pastures. | | Ahh the SunOS days were really the days of yore | lbriner wrote: | Since I was at college in the second half of the 90s, we still | had unix text consoles for reading emails so my favourite prank | was to tell others in my dorm that I had worked out how to | remotely log in from the dorm (we had to use a computer room back | in them days!) and with my 10 line Turbo Pascal program created a | fake login screen like looked identical to the normal one. After | capturing a password, I would explain to each person that maybe | it wasn't quite working so "sorry", so they were none the wiser | that they had given me their passwords. | | I didn't do anything with the passwords, it was just interesting | how easy it was to get away with. | dspillett wrote: | Someone was discovered to be collecting passwords that way on | our universities VT terminals (I'm old enough that at Uni plain | text terminals were still a thing, though they were generally | used just as terminals for email & such when the lab rooms full | of PCs were fully occupied) by leaving what looked like a login | prompt on-screen. Someone with much tech knowledge immediately | saw it wasn't quite right (that is how the issue was found) but | these were terminals used by the general populace not just us | CompSci students so the vast majority of the users were not at | all technical (what we might assume almost everyone knows these | days was still new fangled magic to the average student back | then, for many arriving at Uni was their first encounter with | having an email account for instance). | | To my knowledge they never worked out who did it, or how long | it had been going on for other than "may have been months", | because the fake login app would exit and logout after sending | off the captured credential, and next time it was run it was | done from one of the captured accounts, so only the very first | capture would have been done by the culprit's own account (even | that maybe not if they'd guessed or stolen a password by other | means first). Captured credentials were sent to a popular high | volume usenet newsgroup so they couldn't track who was reading | the result that way. Also, no evidence of the attacker actually | using the compromised credentials for anything else, so it was | possibly someone "playing" to see what they could do rather | than a more malicious intent. | | It became standard practise ("enforced" by notices in large all | caps text) to reset terminals before logging in to be more sure | that was a real login prompt. | loph wrote: | I once set up a job on a co-workers VAXstation 3100 that would | run XCrab every 10 minutes. What is XCrab? It is an annoying | little program, when it runs a crab scurries across the screen, | grabs the mouse pointer, and runs off the screen with it. I | renamed the job PRT$SYMBIOINT so it looked like part of the print | spooler, he never figured it out. | Ensorceled wrote: | I installed that on a coworker's machine only to find out he had | a bug phobia. He shrieked like a kindergartener! I had to buy him | beers for weeks before he forgave me. | fvdessen wrote: | This story is either fake or exaggerated, the number of roaches | in xroach is constant, and there's a hard limit as they are | statically allocated (I checked the original source code) | nuancebydefault wrote: | I never heard before about roaches that can be minimized. Reminds | me of the original meaning if debugging -- physically removing | cockroaches. | | Probably the story would sound more funny to me if I knew more | about xwindows and SPARCs? | fcatalan wrote: | Mid 90s were fun at Uni. | | Replacing a T-connector with a broken one to sabotage unpopular | classes... Or binary searching it with a terminator to save one | you liked... | | Learning that pinging Windows 3.1 with a big payload would BSOD | it and writing a script to perform a rolling BSOD of the entire | lab while sitting in the back... | | Sending random insults to random spots on ttys while people read | their mail using Elm... | | Writing a trojan to steal and then delete the MUD accounts of the | dudes hogging the only 2 computers with Internet access available | to undergrads... | | And being caught and let go with a not so stern warning. Simpler | times. | phkahler wrote: | >> Sending random insults to random spots on ttys while people | read their mail using Elm... | | Receiving such a write and tracking down the offender for a | face to face "you got a problem man!?!?" ;-) | fcatalan wrote: | I still treasure friendships forged that way :) | Twirrim wrote: | > Replacing a T-connector with a broken one to sabotage | unpopular classes | | When I started working in academia they had _mostly_ phased out | 10BASE2. Every now and then we 'd get reports of network being | broken and would have to get out the break detector to track | down where. Inevitably we'd find a student had unplugged a | T-connector in a classroom, disrupting the others on the same | loop. | mcv wrote: | I believe either my brother or someone he knew once wrote a | program that spawned lots of child processes. He did that to test | a scheduler or something like that, but it got a bit out of hand | and swamped a major server in endless processes. Admins weren't | pleased. But also not too upset, because they approved of | students experimenting. We had pretty cool admins. | danieldk wrote: | A fork bomb. In shell: :(){ :|:& };: | doetoe wrote: | Could you explain how this works? | system33- wrote: | A function called ':' is defined. In its body, it calls | itself twice at the same time (':|:') (piping the output of | the first call into the second, which doesn't do anything | useful) and sends these calls to the background ('&'). | After function ':' is finished being defined, it is called. | | The first call spawns two clones. Each of those spawn two | more. Etc. | doetoe wrote: | Great, thanks! | xav0989 wrote: | :() defines a new function called : { :|:& } is the body of | the function, where we call the : function recursively, | piping (|) its output to another call to :, then | backgrounding the whole thing (&) ; indicate the end of a | statement and the start of a new one : and finally the last | : calls the function we defined to start the chain | | Essentially each time the function is ran, it creates 2 new | copies of itself, which each create 2 copies of themselves, | etc. until your OS stops responding and crashes. | | Nowadays many shells recognize this particular fork bomb | and refuse to execute it | _flux wrote: | > Nowadays many shells recognize this particular fork | bomb and refuse to execute it | | Nice try! | | Though, do they really? I quickly checked if I would find | something like this in bash, zsh or tcsh and failed, but | I only spent a minute or so.. | sva_ wrote: | Well I can experimentally confirm that it works on | zsh/alacritty ;) | [deleted] | [deleted] | mcguire wrote: | Oh, lord. The sheer number of fork-bombs launched by the | students in the systems programming course the week the | professor introduced fork().... | sam99x wrote: | In the early '90s, I was a fresh Computer Science undergraduate | student at a state university. Our computer lab was packed with | the Sun SPARCstation IPCs, each running SunOS. We had this | rudimentary email system that everyone in the department used to | communicate. The tech-savvy folks, of course, had started | exploring Usenet, but for the majority of us, the e-mail was our | digital universe. | | One day, my group of friends and I decided to have some fun. We | concocted an idea inspired by the famous 'fortune' command that | prints out random adages. We wrote a simple shell script that | would take a random line from a text file full of humorous and | nonsensical messages we'd written, then mail it to a random user | in the computer science department. The script was set up as a | cron job, scheduled to send one of these messages every hour. | | Initially, it was just a harmless prank. People found the | messages funny and would often share them in the lab. The source | of these messages became the talk of the department, but nobody | knew where they were coming from. We took great pleasure in | watching our peers and professors speculating about the | mysterious sender. | | However, things started to get out of hand when the Dean received | an especially absurd message that read, "Why do computer | scientists confuse Christmas and Halloween? Because Oct 31 == Dec | 25!" He found the joke incomprehensible and thought it was some | sort of cryptic message or even a potential threat. | | The campus IT team was called in to investigate, and a week-long | frenzy ensued as they tried to trace the source of the emails. My | friends and I watched in trepidation, wondering if we'd be found | out and expelled for our seemingly harmless prank. | | Finally, after several sleepless nights, we decided to turn | ourselves in. We went to the Dean and confessed. After an anxious | silence, he started laughing. Apparently, he had been let in on | the joke by one of the Computer Science professors and was | waiting to see how long it would take for us to come forward. He | was good-natured about the prank and found our initiative | creative, although he warned us about the unintended consequences | of such pranks. | | Looking back, it was a fun, memorable prank that gave us a | valuable lesson about the ethics of technology use. It's a story | I often recount when I'm teaching my own Computer Science | students about the importance of ethical conduct in the digital | world. | unilynx wrote: | The interesting part is that it occurred to no one to just reboot | and see if that fixes it. Apparently systems were a lot stabler. | kristopolous wrote: | Calling IT is the right move here. Could have been an intruder | or a remote user doing something important. | | It's a different relationship. The department workstations were | much closer to the refrigerator or copy machine. If it's broken | you don't touch it and just call somebody. | | In modern money these machines were between $7,000-$10,000 each | depending on configuration. | | To put it in context, pretend you work somewhere where they | provide you with a half height rack and a Precision 7960 | https://www.dell.com/en-us/shop/workstations-isv-certified/p... | | And it starts acting up. What do you do? | | (As an aside, I've always wondered how many maxed out | configuration orders they get - you know, when you kick that | price up to $100k - what's the threshold where they ask if they | could put someone on a plane to visit you? 10 of them?) | eru wrote: | I'd probably reboot it every day (or every week) as a matter | of course. Not just when there are problems. | | Just so that I know that there are no unexpected surprises | happening when I need to reboot it in an emergency. | aflag wrote: | That sounds needlessly disruptive. It is a workstation | after all. I restart mine as little as I'm allowed to and | once a month sounds way too much already. | dmbche wrote: | What is the negative? | aflag wrote: | You have to close all windows (and possibly tabs in your | editor), restart long running jobs you have in the | background, restart your SSH sessions, lose your undo | tree, lose all the variables you have loaded in your | interpreter or bash, among others that I have possibly | forgotten. | | All recoverable, but annoying. I can't imagine doing that | every day. It's fine for a home computer, but for a | workstation, I just want it always on. Though these days | even my personal laptop is essentially always on. | computerfriend wrote: | Downtime. | kristopolous wrote: | At least on older hardware, number of reboots was a | stronger correlative with failure than hours on. | | I'll readily admit this may have been apocryphal. It was | a common adage when I was a child in the 80s and now that | I'm actually qualified enough to suss out such a | statement I've never cracked open the historical | literature at archive.org on this one to actually check. | | It could just be a portage from incandescent lightbulbs | (where this is true) and older cars (where this is also | true). The idea of non-technicals thinking magical | computer dust having the same problem is understandable | pjc50 wrote: | Somewhat against UNIX culture. There used to be proudness | in having very high system uptimes. The modern security | arms race has basically killed that. | somat wrote: | I don't think that long uptimes is unix culture at all. | unix was always about being small, simple and fun to use, | A place where having something now is much more valuable | than being correct later. A hackers OS. This is also | where most of the sins of unix come from. | | "We went to lunch afterward, and I remarked to Dennis | that easily half the code I was writing in Multics was | error recovery code. He said, "We left all that stuff | out. If there's an error, we have this routine called | panic(), and when it is called, the machine crashes, and | you holler down the hall, 'Hey, reboot it.'" | | https://multicians.org/unix.html | AnimalMuppet wrote: | Not sure it's just security. I wonder if it's also that | people don't host important services on non-redundant | machines as much anymore. | TristanBall wrote: | I'd guess orders for these probably skew to the higher end. | | If you're putting workstations in racks it's either to share | them, or due for power/cooling/noise reasons, and the fact | that you've got a workload that justifies having those kind | of problems probably means all your other costs will still | dwarf hardware. | | There's usually a large premium on whatever the current | largest size dimms, ssds and the top 10% or so of cpus and | video cards. So I expect they sell a lot of machines that are | "50%" size ( either max physical capacity with 50% size | components, or half physical capacity, with 90-100% | components ), and a fair number of maxed out just because it | will often be cheaper to have 1 maxed out option then 3 | smaller ones, and budgets don't matter except they do. | | Places who cost engineering time at $100k/hour won't blink at | $100k computers if it gets the job done. | tmn007 wrote: | Hard reboot on those old Sun systems usually meant a dirty | filesystem and telling off by the admin as they needed an fsck | IggleSniggle wrote: | No matter how many times I see it I always read fsck as | "(for) fucks sake" and then internally correct to "file | system check." I think I've got a flashbulb stressful memory | floating around in there. | r_klancer wrote: | The headline put me in mind of a different memory I had of the | campus BBS from undergraduate days, and then I clicked through | and realized that the author was actually the admin of that BBS! | | Anyway, in addition to the BBS there was also an IBM mainframe | (?) running VM/SP that you could connect to, and somehow that was | how you got to IRC. | | One night several of us spent hours chatting on IRC, and the next | day we got called into the campus computing service where it was | patiently explained that some professor's overnight batch job | running stats had failed because it was constantly being | interrupted by interactive-priority jobs ... i.e., our chat | sessions. Which we should now stop. | | I remember writing a passionate open letter using my vague | knowledge that had trickled out about "hacker culture" in places | like Berkeley where students were surely right now exploring | these new things called "Usenet" and "the Internet", arguing that | even though _we_ weren 't doing anything fancy like running stats | for an economics paper, and even though we didn't know what any | of it would actually amount to, the important thing for our | education was that we had the chance to experiment with it for | ourselves... | bigjump wrote: | The simple pranks are the best. | | We just used to add an alias for 'ls' which introduced a subtle, | but ever increasing delay each time it was run. | _flux wrote: | Debian also comes with the package 'sl' that can be amusing. At | first at least. | raverbashing wrote: | Is it too late to open a bug with the xroach developers? | oaiey wrote: | while (fork()) { while (malloc(1000)) { } | } while (true) {} // or whatever true was in good old C | ;) | | my most loved program when I was a young student on a mainframe | with 20 other kids. | boffinAudio wrote: | We used to 'rain-bomb' each others terminals: | | $ rain | wall | | This was always really fun with the newcomers to the ops centers | .. | notbeuller wrote: | Our unix (Gould GLX or something?) with dozens of terminals | lacked appropriate permissions on /dev/ttyNN - so we just piped | rain directly to the neighbors terminal. | nickdothutton wrote: | In my day we ran irc servers and MUDs on the professors | workstations, which were of course tied in to the campus-wide | NIS/NIS+ system, and often more lightly loaded than the big iron | (that being VAX6000 or 8000, or if you were lucky a Sparc20). | poutine wrote: | Back in the day I played a prank on a fellow sysadmin by adding | an 'echo "sleep 1" >> .login' | | Took him a week to figure it out, he was not pleased. :) | deckar01 wrote: | I once had to troubleshoot the math department director's PC | misbehaving. It turned out that he let prime95 have every spare | cycle on a core 2 duo for a decade and the machine would only | boot if it had cooled to room temperature. | Exmoor wrote: | It took me way too long to remember that Prime95 is useful for | something other than stress testing. | oxygen_crisis wrote: | Looks like the project averaged about one new Mersenne Prime | per year for 1996-2009, and then only 4 hits for 2010-2018 | with none since 2018. | | Obviously the tflops::hit difficulty ratio is ramping up as | the numbers get larger, but I can't help wondering if the | cryptocurrency craze dampened their work rate. | | They're reporting 78,012 tflops of work done today, but my | five minutes of investigation wasn't enough to find a | historical chart of tflops/day and five minutes is about the | limit of my curiosity on this matter for now. | jl6 wrote: | When the project started, CPU frequency scaling wasn't a | thing, so CPUs would run at full speed (and full power | draw) 100% of the time. If you weren't making maximal use | of the CPU, any remaining capacity would go to waste. | Distributed computing projects could make use of that | remaining capacity. | | Today, CPUs are built with power efficiency in mind, and | will attempt to scale down rapidly when not fully in use. | Thus there is no longer such a thing as "spare CPU time". | Any time spent on distributed computing projects is paid | for in electricity costs. Some choose to continue anyway, | but many have been disincentivized. | organsnyder wrote: | For a while I had a Home Assistant automation that would | spin up Prime95 on a machine in my homelab when the | closet it was in (in an unheated garage) got too cold. | The closet also has the water meter, so it has to be kept | above freezing. There's also a resistive heater, but I | figured I'd rather get a bit of productive use out of | those watts. | | Then I realized that the computers heated the closet | plenty without artificially pegging CPUs, so I didn't | bother reimplementing it when I did a migration. | tedunangst wrote: | The hlt instruction has been around for a while. | post-it wrote: | I don't think that saved any power on a CPU without | frequency scaling. | spookthesunset wrote: | Hmmm.... there was some windows program called | "waterfall" that kept your CPU cool when it was idle. | Very useful for overclockers. | ChainOfFools wrote: | It may have been replaced by a cryptocurrency indeed, for | there was PrimeCoin, one of the very few that actually did | something that was both productive and unprofitable | (critically important for the economics of mining) with its | mining cycles, and that is look for prime numbers. Although | I don't remember if these were Mersenne Primes. It was one | of the very earliest altcoins and by its nature was CPU | bound which made it unpopular with large scale mining | farms, but extremely popular with CPU cycle thieves working | in clueless corporate and educational IT departments. | JTbane wrote: | Unused cycles are wasted cycles. /s | ufo wrote: | Does anyone know where we find a video of xroach in action? | mcguire wrote: | Once upon a time a (fameous) CS professor reported that his email | was annoyingly slow. | | He was using the good ol' mailx MUA. | | He never deleted emails. | | He never moved emails out of his inbox. | | He had been doing this for many years. | | His .mbox file was many, many megabytes. | | Apparently, he had never noticed the problem before because he | very rarely logged out, but IIRC some system work meant he needed | to do so several times just prior to his complaint. | lizknope wrote: | I was in college in the mid 1990's. Our school had hundreds of | Unix workstations from Sun, HP, DEC, IBM, and SGI. Everything was | tied together with MIT's Project Athena which used the AFS Andrew | File System, Kerberos, and the Zephyr instant messaging system. | | Your home dir would be mounted as /school/login | | The directory paths would be really long like | /afs/school/math/maple/maple5.3 so there were 2 commands named | add and attach to mount dirs to /school | | add maple5.3 and you would have /school/maple5.3 and it would | source .environment script in that dir to set up the tool and it | /school/maple5.3/bin to your PATH | | The attach command did the same thing but did NOT source the | .environment file | | If you needed to access another student's dir it was explicitly | written in the intro computing class book to use attach and not | add | | I had a lot of scripts and utilities that friends would use. They | told other random people that I didn't know. | | So of course I made a file that would be updated any time I | logged in showing my current machine name. Then I made a | .environment file that would xhost + my_machine and send me a | Zephyr message saying "I just added and xhosted your machine" | | I would wait a few minutes and then run xflip and xmeltdown and | set the -display to their machine. If they were in the same | computer lab as me I would see them start to freak out. These | programs basically froze your display for a few seconds while | inverting the screen or causing everything to appear to melt to | the bottom. | | https://github.com/veltzer/xmeltdown | | No real harm but it was pretty funny when I was 19 | zerealshadowban wrote: | for OS class we had to write a distributed game on top of the | Andrew File System; debugging a nasty crash I managed to | distill our team's code down to 10 lines to remotely | crash/reboot any chosen AFS workstation on campus; thus I | regularly emptied workstation rooms at CMU (most students just | gave up after a couple of sudden computer reboots) so that CS | friends could work on and finish their homework; I may have | also crashed some professor workstations from time to time, idk | lizknope wrote: | I still miss AFS ACLs. | | For the last 25 years at 8 different jobs everything is over | NFS. Every company uses Unix groups and some have used groups | to manage project access. Sometimes it can take 3 days to get | added to a group. | | When I started college in 1993 we learned in the "Intro to | Computing Environment" class our first semester how to create | ACL groups. | | I have a degree in computer engineering so I understand | binary, octal, hexadecimal, but chmod 755 or 644 or whatever | is not exactly intuitive. | | AFS permissions are much easier to understand. When we had a | group project we would all make a directory for that project | and only give access to the other people in our group. We | could give them read or write and everything worked great. | | I know NFSv4 has ACL support but I've never seen it actually | used anywhere. | nirui wrote: | > Please be aware that this version still has some bugs | | That's ... very obvious, but thanks for the reminder. | RegnisGnaw wrote: | In unversity, I was bored one day and added this to another | student's .bashrc echo "sleep 1" >> ~/.bashrc | | He used the Solaris SPARC machines to do his work, so everytime | it logged in it opened 4 terminals or so (not sure why). By the | time he asked the help desk for help, it was up to a 6 minute | wait after logging in before he got the prompt. | once_inc wrote: | Once when doing tech support at a local hospital, one of the | nurses called us stating that she had "some sort of weather | report" up in a window on screen, but she couldn't click it away | because the most would go under the screen. Obviously piquing my | interest, I told her not to touch the computer until I arrived. | | Since the hospital was quite big, it took me about 10 minutes to | reach her workstation, where she exclaimed that "the window | closed on its own a minute ago. I swear it was on there for half | an hour". | | That, coupled with the layout of the desk, the description of the | window led me to a hypothesis. I pressed the button on the | monitor (which she had unknowingly pressed with the corner of her | keyboard) which called up the system menu of the display. It | showed 100% sun (brightness). The mouse would go under it. | | Then, I hiked back another 10 minutes to await the next phone | call. | nuancebydefault wrote: | Nice story! Sounds like the more advanced version of the "my | 4x-labeled cupholder is broken" story of the nineties. | | In fact the nurse gave a quite accurate description of events i | might add. | c22 wrote: | I had to do a tech support call once where 'the screen keeps | glitching out I think I have a virus' ( _The Net_ was still in | theaters). I showed up, removed the boombox with two large | speakers from on top of the CRT and like magic the problem was | solved! | nyanpasu64 wrote: | I have the misfortune of my rescued VGA CRT displaying | incorrect colors in the corners, unless I either leave | magnets on the screen, or flip the magnets while degaussing | and remove them before using the display. | tomcam wrote: | Well now I need to know what you can use a VGA for these | days | arcanemachiner wrote: | 640x480, but that's not important right now. | gtk40 wrote: | Works great in old conference rooms... I have a USB-C VGA | adapter in my bag still. | [deleted] | mulmen wrote: | I also did tech support in a hospital. I'm not sure IT is a | value add in that environment, at least not as much as IT | thinks it is. Nurses are busy doing things like saving lives | and caring for people experiencing the worst day of their life. | On top of that nurses have to deal with poorly implemented and | maintained workstations. Then when they ask for help the very | people who created the problem in the first place come and | belittle them. | | I'm not accusing you of anything. Just noting my own perception | that IT people tend to be very smug and see the world from an | IT-centric perspective. Nurses aren't dumb and they certainly | aren't lazy. They just have better things to do with their time | than deal with inconsequential IT issues. | | As I recall everything in the hospital that was actually | critical to providing care had some specialist that maintained | the system. The computer running the MRI machine wasn't bound | to Active Directory and might not even be on the network. | Issues with it were routed to GE, not the guy that fixes | printers. | tiffanyg wrote: | Ha - I know where you're coming from, but, like every | opinionated SOB on this site, can't help but throw in my own | opinion*: | | 1) The parent comment seems completely neutral and non- | judgmental. Seems quite just "I had this experience", | essentially a set of facts (compared to frequent enough | comments that possibly really ought to generate a response / | "note of approbation"). | | 2) Stereotypes are the epitome of judgmental thinking, | language, attitudes, etc. That may sound judgmental itself, | and I apologize for that - that's due, in part, to | connotation "issues" with words we use (although, I can't, | obviously, claim that even removing those removes all of that | issue - I am literally labeling and characterizing strictly | in denotation). To be fair, people, in general, can be very | smug. | | In my experience, there has been an "enrichment" of that in | "IT", but, for example, try talking to some of the especially | high-ranking surgeons, say ... or, certain professors. In | particular, I've personally come across a somewhat bimodal | distribution, I think. Some people who reach "very high | levels of expertise" are very humble ("right-sized" - not | subservient or etc.) and super nice (surprisingly willing to | help and talk to even "the layman" / "novice"). Then, there | are the outright "arrogant bastards". | | So, to add some kind of summation - calling out "IT people" | specifically, and especially the parent comment ... well, | what's the point? Again - not meant to be rhetorical or | aggressive ... but, I think many would agree that people in | general should cut that $h1t out. | | _This opinion brought to you by my "Big Giant Head... | remember, when you're thinking of giant heads, think [my] Big | Giant Head..."_** | | * Which, we all know is likely to be comparable to ... | something else everyone's got. Though, I'm telling myself, of | course, that I've got something useful to say. "Caveat | lector". :) | | ** With apologies to the writers and other people involved in | making "3rd Rock from the Sun" | rat9988 wrote: | You are way too apologetic with the original post. It was | not just a set of facts. You could feel the superior | attitude. It's kind of obvious in the last sentence. The | person you answer did well to call it out. | richie_adler wrote: | I read the post in Mastodon with a tone of amused | incredulity at the unusual situation. Yes, some unusual | habits of the professor may have contributed, but I don't | read any negative judgement there. | | Somebody got burned too many times with IT people, I | think. | [deleted] | ShakataGaNai wrote: | Every group of people who's remotely decently specialized... | will get very smug assholes. I've met IT people who just want | to help you get your shit done, and those who look down at | you for being a "stupid user". Also I've met Doctors whom | think they are god, and Doctor's who want to be a partner in | your health journey and are totally non-judgemental (at least | outwardly). | | I'm sure you'd find the same in any similar field. Engineers. | Pilots. Mechanics. Nurses. | | And yes, everyone looks at the world from their personally | centric view of the world. It's the only way we, as humans, | know how. After all, how would you get to your oh-so- | important job if not for the road engineer, or the mechanic | who built your car, or the city designer who designed the | routes that you use every day. | | Some are more aware of main character syndrome [1] than | others... and some are just less assholes than others. | | [1] https://www.cxomedia.id/human- | stories/20220722170529-74-1756... | [deleted] | nuancebydefault wrote: | Thanks for sharing the interesting article! | teh_klev wrote: | Seeing as we're sharing our fun and games... | | When I was at college back in the 80's we had access as students | to the college's VAX 11/750 (an 8750 Systime clone) to work on | our coding projects. The student terminals were on one half of a | large divided room, the other half being used by the college IT | folks. Often, if there wasn't a spare terminal on the IT admin | half of the room, one or two of the IT folks would use two of the | nearest terminals just over the divider. | | One day, bored out of my mind waiting for my COBOL project to | compile, I wondered if I could capture the sys admin's username | and password. I wrote a script using the CLI to perfectly | simulate the login prompt complete with beeps, messages and all. | All it did was clear the screen, sit there waiting for user to | enter their username and password, when they did the script would | mail me said username and password, display a username/password | error then logout to the real login process. | | After trying the script out on a couple of unsuspecting | classmates and having a bit of anonymous tomfoolery I decided it | was time to try this out for real with the sysadmins. I logged | into both terminals the IT folks normally used and left the | script running. A few hours later I returned and to my surprise | and mild anxiety I found out that I'd captured the SYSTEM login | password :o. For about a month or so I'd full control of that | machine, and would re-run the script occasionally whenever the | SYSTEM password changed. I told no-one and on my last day at | college logged in and deleted the script, just in case (this was | around the time the law in the UK was getting a bit heavy with | regards to unauthorised computer access). | | Combined with access to the huge set of manuals for that machine | I spent a heap of time exploring and learning about VMS and no- | one had a clue. | samch wrote: | Fun fact: Login spoofing like this is why, from Windows NT on, | users have had to first enter a security context with | Ctrl+Alt+Del. | | https://en.wikipedia.org/wiki/Control-Alt-Delete | gumby wrote: | an approach that goes back the the rainbow books, at least. | There was some scheme to use the "break" key on the teletype | for this (maybe in Multics, or OS/360 perhaps?) but I have no | idea if it was ever implemented. | | For those who don't remember, "break" was not an ASCII | character but a literal long unmaskable pause in | transmission, and couldn't be generated in software or by | reading the paper tape punch, nor could it be read on the | host side into an input buffer as it wasn't a character. | eichin wrote: | The magic words being "Secure Attention Key" (on multics in | particular, it was specifically caught by the Front End | Processor, so nothing in the OS could interfere by (for | example) catching the signal and printing a fake login | prompt, becauase it was literally a separate computer | handling the request...) | TimTheTinker wrote: | In MS-DOS, Ctrl+Break could be simulated through ASCII | character 0x03. Literally, hit Alt+3 and it would respond | the same way. | | The sysadmin for my high school computer lab had written a | text-mode DOS login screen that would start Windows 3.11 | for workgroups after the user logged in. A few of us kids | figured out we could just Ctrl+Break out of it and | install/play DOOM, Descent 2, etc. He wised up and wrote a | trap for the Ctrl+Break sequence, but I discovered the | Alt+3 trick and we continued on our merry way. I don't | think he ever figured out how we did it. | | (We also hid our games inside a directory named Alt+255, | which appeared as a space. A single space was not allowed | as a directory name, so it felt like magic to us.) | chx wrote: | Ha yes, name your TSR keylogger REMalt+255.COM , put it | into AUTOEXEC.BAT , it looks like an innocent comment. | 0x6c6f6c wrote: | This is great. Reminds me of the BASIC program I wrote on my | Ti-83 to simulate the memory reset process for algebra tests | because our teacher walked around and would run it himself. | | Big surprise now I program for a living. | teh_klev wrote: | > Big surprise now I program for a living. | | Oddly, me too :) | gonzus wrote: | This seems like a rite of passage... I did the same thing with | the VAX at my school, but decided to come clean and gave the | sysadmin all the passwords I gathered after one day (including | several with SYSTEM privileges). They gave me my first job :-). | I also made sure to grant the necessary permissions to one or | two obscure accounts, so that I could regain SYSTEM when it was | revoked on my "official" accounts. Fun times, and innocent too | -- I never used the privileges to cause havoc. | intrasight wrote: | I recall a student at CMU getting in big trouble for doing that | - around 1985. | dormento wrote: | Its funny how writing a user login replacement seems kind of | ubiquitous for all future hackers. Mine was in Visual Basic (5 | iirc) for a Windows (Novell?) network. This was back in school. | You could trivially change win.ini to set it up to run _before_ | the real login screen. Mine would save the username and | password to either a shared network drive or a local file, then | display a "password error" and exit to the real login prompt. | | What got me in the end was that a "friend" used the same trick | and started copying peoples files from their network account to | his own. My suspicion is that when he eventually maxed his | quota, the system must've warned the network admin... a cursory | look would later reveal he copied some teacher's thesis files, | and that was a big no no. | | Eventually this incident would land me my first computer | related job as a junior tech support/network admin. | db48x wrote: | Stories about software bugs are the best :D | rwmj wrote: | Back in the day we banned using animated xlock to lock your | screen. The Sun workstations in the lab ran the X server local | and picked a random other machine to run the window manager and | clients when you logged in. (Which is kind of an odd way to do it | when I think about it now, but also cool that it was possible.) | However this was all running over shared 10 Mbps ethernet with | probably 100 machines and only 2 or 3 segments. This all worked | fine until a few people use animated xlock running remotely over | the shared network. | dspillett wrote: | _> ran the X server local and picked a random other machine to | run the window manager and clients_ | | Are you sure they were full workstations and not more dumb | terminals (just enough processing power to be an X display) | with all your logins being to a central beefy server (or one of | a few) rather than some random machine? | | If that were the case then an animated xlock would potentially | chew up an unfair amount of CPU time as well as clogging the | network spitting the results out to your local X display. | rwmj wrote: | Some were indeed "dumb" X terminals, but most were top of the | line Sun workstations provided at greatly reduced cost to the | university. | | The best machines were the few HP PA-RISC ones though. | Blazing fast. ___________________________________________________________________ (page generated 2023-07-25 23:01 UTC)