Understanding Fork Bombs in 5 Minutes or Less
Вставка
- Опубліковано 17 лип 2024
- You've probably seen a fork bomb before, but do you understand how it works? In this video you'll find out.
Hope you enjoyed the video!
Check out some code on my GitHub:
github.com/realtux
github.com/engineer-man/youtube
Other Social:
/ engineerman
/ _engineerman
/ discord - Наука та технологія
Warning: Don't run this on your own system. If you want to test it, create a VM like I did.
Why not. Does it not go away ?
Surely hard rebooting the system stops the issue though? With all the normal problems with hard reboots ofcourse.
He probably means that it's the easiest environment to test in and as a general disclaimer to not mess up a system critical machine. At the end of the day you can do whatever you want with your own hardware, just that he's not endorsing it.
Nobody can stop me from running this on our production cluster.
(I have sudo)
Someone (YKIYK) said -
Why are the warnings at the end of the book 😉
Short version: it creates a function called : that calls itself infinitely
Also it calls 2 functions for each function which run at the same time so each step the number of functions is doubled
*Force Multiplication*
I know this classic for over a decade now, but this was such a great video explaining it in detail! Thats the content i love this channel for. No BS straight to the point. ❤
Great explanation! The expanded version really made it go from black magic to "oh it's that simple"
I love videos like these. Straight to the point, clearly explained with concise examples and demonstrations
Wow that's interesting! Love the breakdown of how that code actually worked
That's why I love your content EM. Learning so much from you. Keep them coming :)
Great video, great explanation! Thank you for putting in the effort each time!
Thanks for the kind words.
dude idk how i havent came across your content yet but i dig it.
Fantastic explanation, quality video
Great education. Appreciated.
great video. concise and informative
Wow!! this guy actually explained it very well.. I like it
I love this new series
Great explanation!
Very clear, thank you again
great explanation!
Great explanation
I've seen it a number of times recently. Used to be kind of common, then it seemed to get old and I didn't see it so much, now it seems to be common again.
keep it up brother, have a nice day everyone
Excellent video
" this is the initial call to fork me"
How did you say that with a straight face.. Cuz I am rolling 😂 😂
The colon being a valid function name was what blew my mind. :D
Great video
You have to love it!
I actually did this in my phone, good thing I did some buttons and it restarted. I was so scared but I was relieved when it restarted successfully.
great video! Brings back memories of crashing uni sun-ray clients ;)
thanks, it was interesting!
Pipe is not the real issue here that causes program to explode. When you running a function, shell executes whatever command you gave it (and forks itself to execute external programs), but ampersand makes shell not to wait for a job to complete and then return but instead put that job in a background and let user to cleanup it with a wait command manualy.
What is a job? Job is basically a group of processes with the same Process group ID (read manpage 7 credentials to learn more). Shell, when you launch several command with a pipe between them, first calls fork, then in a child assigns the same PGID as it's PID to itself, then it calls more forks which will inherit the same PGID (despite having new PIDs) with their stdins and stdouts connected one to another, and then each of that child executes whatever command you gave it to execute.
Why PGID needed? To call kill command on the whole group of processes with the same PGID instead of calling kill to each one of them, or even lose control when initial child died and replaced itself with a new process with new PID. Since PGID is inherited by the child, and if child does not changes it explicitly by calling setpgid, you can just `kill -- -${child_pid}` (notice the minus before the process id and double-minus to make kill take that negative pid not as another option but as a pid value). This is how shell kills the whole pipe sequence at once.
And yes, if child changes its PGID, its becoming immune to group kill (the game was rigged from the start), which does makes sence, but its hard to work around this if you really want to end all child and grandchildren processes, if at all possible. Try to write cron yourself, you will spend on it at least a hour or two of experimenting with what works and what not if you start from scratch knowing nothing about jobs, PGID, SID, what kill and wait calls allow you to do and what permissions you have to play with for changing processes credentials.
You can do the same on Windows, but normally the system does not outright crash and you can recover from that (with taskmanager).
Cool! I've created a jpeg bomb of 530 bytes that renders 4 billion pixels to the screen when opened. It freezes my laptop.. lol.
I achieved this neat trick in Notepad ++ by accident when editing the Hex values in the dimensions sector of the code....
i understood the fork bomb at 1:00 great title
Noice 👌 Thanks for sharing 👍
I kinda accidentally let it loose on the uni network and it crashed the network for a few days and I got failed :(
Cant you do the same thing without the pipe? It feels like
f(){f&}; f should do the same job. If you want to increase the forks exponentially, just have each function run two other ones like so:
f(){f&; f&}; f
Might be written with a pipe to make things neater or smaller
look at @rogo7330 comments
Thanks. But the most interesting part with pipe and fork itself were not covered:( You said pipe is what actually creates a fork bomb, but why?
yeah, I also missed that. In my head, the second argument is waiting for the given input by the first one, so it should remain inactive. The only thing that I know is that the prior is wrong xD
look at @rogo7330 comments
@@patocarrasco6266this is the exact same question I have. Does anyone have an answer?
Piped processes are launched by bash in parallel
It's tempting
so it's basically how all my recursion functions go? :))))
How did you replace semicolons with text?
Pipe bomb would've been a great name for this
Delightful
Time to run it on my system
are you able to pipe it multiple times inside the same command to make it crash the system faster?
I don't think it would make a meaningful difference. You'd crash the system in fewer generations, but it would take longer to resolve each instance of the process.
My roommate will love this prank
hey guys i want to know what other pranks have u done like this?
Awesomeness 🎉
Spoon Nuke next plz
Great!
Nice didn't know you could limit number of processes for a user
do you need the &?
I wonder how this does on WSL
what if i write this in my bashrc ?
Awesome 👍
type the command 'gnome-terminal' (or any other command that opens a bash shell) in the end of the .bashrc file and save it and then see the magic when you open a terminal.😂 You might to do it in the .zshrc file depending on the type of shell you are using (bash or zsh = Bourne Again Shell or Z shell).
you won a subscriber
what do you mean by "friends on linux"?
when you use fish shell for several good reasons and the "expert professionals" roll their eyes at you.
The only reason I was confused when I first saw this was that I didn't know you could use a colon as a function name. It makes much more sense as f(){f|f&};f
It seems many modern 'nux systems default to limiting the number of forks a process can start now.
Could you please show your hotkeys for the editor?
Does not :(){:&;:&} do the same thing (without pipe) ?
This isn't a fork bomb it's a picture of a cat.
fyi: i have tested this code on my android phone and it works 😂
forbidden emojis are teh most powahful
What about :(){:&;:&);:
Also exponential or linear?
It will do the same as at 4:25
shouldn't proliferating dummy processes just hang the system forever?
why would it crash the system anyway?
Oh THAT's why you don't want everything to be run by the root user
Fork me, that was a good video! ;-)
if you set the video playing speed fast enough you can almost hear "fork me" to another very similar term
What happens if instead of piping, you start 2 background processes each time? like :(){:&:&};:
So i got trolled in a stackoverflow question...
Oh no I'm wrong, your right eyebrow is still always higher than the other one
I remember my first attempt at a fork bomb, it was perhaps 15 years ago in high school and I wrote it in C, it didn't really work too well, I probably had some more advanced scheduler than I thought and while it slowed down my computer I was able to still kill the process. But I added a small malloc (about 4k if I remember correctly) in the loop ant it totally freezed my computer in seconds. Fun times
Edit: If I had known more when I was young I'd probably done a mix of forking and daemonizing to try to hit it harder
Ran this on production server for fun, bos didn't seem really enjoy it
i was sad when browsers started detecting and halting infinite javascript recursions
I made a batch bomb in the 90s.
Fork me, this is interesting!(:
ah yes, for(;;){fork();} good times...
stress testing without a stop 🛑 button 😅
So you watched Dave's Garage and made your own fork bomb video. K.
"Fork me". That's what she said.
Hilarious 🎉
the VM setup is questional, you said you had to restart your system and the VM. sounds like you gave it too much pc resources or using some vm i never heard about before which doesnt asign a limited number of resources in order to run it.
I only had to restart the VM, not my whole system.
@@EngineerMan you did say in the video something about your vm and the whole system after it crashed. might have misunderstood but to me it did sound like you said you had to restart the whole system.
Can you please tecah us these skills. Please 🙏🙏🙏
Reminds me of the prankster batch files for cmd.exe I used to make during my windows years. The simplest I managed to create (DO NOT RUN THIS)
%0 >> %0
%0
With an empty line after,
I prefer the spoon bomb
You can fix a lot of problems in Linux by running sudo dd if=/dev/null of=/dev/sda
Is your name a Daniel?
It is Not exponential. it is just times 2.
Exponential is repeated multiplication. So it is exponential because it is multiplying by 2 over and over
hi :)
Systemd solution this.... Límite del 30% de procesos máximos del sistema.
Cat :3
%0|%0 is the windows version it is fun
How is your eyebrow straight again
fork bombs are for dorks
"There is ways"
There are.
Being an old fart, I have to point out that the fork bomb existed prior to linux, albeit with the same shell syntax you describe. en.wikipedia.org/wiki/Fork_bomb
What if i run it on an instance 🥸