From: bqt@softjar.se (Johnny Billquist)
Subject: [pups] User Mode DoS Attacks (was Re: Issues of AUUGN)
Date: Thu, 05 Oct 2006 16:44:36 +0200 [thread overview]
Message-ID: <45251A54.9040601@softjar.se> (raw)
In-Reply-To: <4672.134.198.172.102.1160058799.squirrel@www.cs.scranton.edu>
Back in those days, there didn't exist any process limits, except for
system wide ones... :-)
Another fun exercise that actually hurts systems today, but didn't hurt
much back then, are programs that allocate a large chunk of memory and
hit on a single address on each page repetedly.
Talk about thrashing the memory system... :-) But on the PDP-11, you
don't use demand paging, nor can you allocate that much memory.
Johnny
Bill Gunshannon wrote:
>>>But you'd need kernel mode for that; this is a DoS attack (one of the
>>>first?) launched by a user.
>>
>>The userland DoS I remember:
>>
>>main() {
>> while(1)
>> fork();
>>}
>
>
> Typical "Rabbit Program".
>
>
>>And in fact I tried it once on the 11/45 I had access to. Not pretty.
>>It can be made less disastrous by judicious addition of a wait(); call.
>>
>>--Milo, wondering how contemporary UNIX will deal with such
>>pathological behavior....
>
>
> Not necessarily pathological. I have students do it all the time
> in the early parts of the Operating Systems Course. The only one
> it denies service to on contemorary UNIX is the individual who does
> it. Process limits are by user, not by system.
>
> bill
>
next prev parent reply other threads:[~2006-10-05 14:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.1.1160013601.40099.pups@minnie.tuhs.org>
2006-10-05 13:46 ` Milo Velimirovic
2006-10-05 14:33 ` Bill Gunshannon
2006-10-05 14:44 ` Johnny Billquist [this message]
2006-10-05 14:51 ` Tore Sinding Bekkedal
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