I tried the fork bomb code :
:(){:|:&};:
and closed the PuTTy. Now it is not accepting the new connections(Denial of Service attack).
How can I recover from that ?
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4 Answers
6
You might need to hard reboot the computer.
Assuming you have console access, you might try to get the process group ID (PGID) and kill that with :
kill -- -PGID
Or use SIGKILL instead of SIGTERM :
kill -9 -- -PGID
but it might not be possible to get the PGID practically as the system might be already occupied by the forked processes creating a deadlock.
This deadlock can happen when you don't have a sufficient limit on the number of processes a user or group can own, so it's better to set a lower limit before trying something destructive like a fork-bomb.
5
You have used the classic "fork bomb" to use up all of your system's processes, and now your cannot get the system to run a process to help you (and all commands, programs, etc. require a process to run "in"). Any intervention will have to come from outside the system (e.g.,reset the VM, cycle the power, CtrlAltDelete). Did you not understand what then code says?
:(){:|:&};:
:()
Define a shell function, called ":".
{
Begin the definition of the function, which is:
:
Call the ":" function.
|
Pipe the output of ":"
:
to another call to ":"
&
Fork a process to put the pipeline (:|:) in the background.
}
End of definition of the function ":"
;
End of the shell statement defining the ":" function
:
Call the ":" function to begin.
If you run code without understanding it, you accept the results of the code.
waltinator
- 37,856
1
According to this it should in theory be possible to use Alt+SysRq+f to get rid of fork bombs — although, again, probably only possible if the kernel is capable of allocating enough memory to kill it.
realkstrawn93
- 171
