Fork bombing a Linux machine as a non-root user
Markku Kolkka
markkuk at tuubi.net
Sat Mar 19 20:39:51 UTC 2005
Johnathan Bailes kirjoitti viestissään (lähetysaika lauantai, 19.
maaliskuuta 2005 17:12):
> On Sat, 19 Mar 2005 08:07:42 -0500, Jim Buchanan
<jbuchana at gmail.com> wrote:
> > I just tried a fork bomb on a reaonably updated fc3 box.
> > Locked it up tight, I had to use the power switch.
> >
> > The default ulimit for user processes was set at 4095.
> >
>
> ulimit -a
> core file size (blocks, -c) 0
> data seg size (kbytes, -d) unlimited
> file size (blocks, -f) unlimited
> pending signals (-i) 1024
> max locked memory (kbytes, -l) 32
> max memory size (kbytes, -m) unlimited
> open files (-n) 1024
> pipe size (512 bytes, -p) 8
> POSIX message queues (bytes, -q) 819200
> stack size (kbytes, -s) 10240
> cpu time (seconds, -t) unlimited
> max user processes (-u) 2045
> virtual memory (kbytes, -v) unlimited
> file locks (-x) unlimited
>
> Weird my fairly stock Fedora Core 3 has a ulimit of 2045?
My machine has the limit set at 8191. Looks like it's determined
dynamically, maybe from RAM size? I have 512MB.
> Is that enough to grind a box to its knees?
Fork bomb jammed my machine with the default limit, with ulimit
-u 1024 there were no problems.
--
Markku Kolkka
markku.kolkka at iki.fi
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