linux-kernel - Re: Fork Bombing Attack

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Message-ID: <m31whdg74i.fsf@maximus.localdomain>
Date:	Fri, 18 May 2007 23:21:49 +0200
From:	Krzysztof Halasa <khc@...waw.pl>
To:	"Anand Jahagirdar" <anandjigar@...il.com>
Cc:	"Ahmed S. Darwish" <darwish.07@...il.com>,
	"Valdis.Kletnieks@...edu" <Valdis.Kletnieks@...edu>,
	linux-kernel@...r.kernel.org, "Coywolf Qi Hunt" <coywolf@...dg.org>
Subject: Re: Fork Bombing Attack

"Anand Jahagirdar" <anandjigar@...il.com> writes:

> ulimit are by default  set to some value for all users.. root, guest.
> on my machine with FC4 distribution when i typed command "ulimit -u"
> it gave me output as 3055 and another machine having FC6 distribution
> output is 8050. when root or any other user changes ulimit by typing
> "ulimit -u value",.ulimit value is changed for that session and not
> permantely. actually ulimit should help to prevent fork bombing attack
> but it wont and fork bombing attack still take down the machine having
> latest linux distributions.

how about:
$ ulimit -u 100
$ for f in `seq 1 500`; do (sleep 100&); done

(on another terminal)
$ ps xa|grep 'sleep 100' |wc -l

mine prints 93.
-- 
Krzysztof Halasa
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