Re: Crashing Unix

From: Nick Maclaren (nmm1@cus.cam.ac.uk)
Date: 04/24/02 

From: nmm1@cus.cam.ac.uk (Nick Maclaren)
Date: 24 Apr 2002 07:43:55 GMT

In article <MPG.172fd44bf509914c989685@news.sover.net>,
Peter <pcc@ecet.vtc.edu> wrote:
>
>In article <aa1bo5$ian$1@pegasus.csx.cam.ac.uk>, nmm1@cus.cam.ac.uk
>says...
>
>> Most serious Unix systems have per-user process count limits, and
>> will survive such things (if properly configured). There are
>> attacks along such lines, but you have to be a bit cleverer.
>
>Indeed... I manage a system that is used by students in programming
>classes. It isn't too unusual for a student program to go nuts and fork()
>in an infinite loop... due to student misunderstanding and not malice.
>Similar things sometimes happen with infinite loops around malloc() or
>open(). I tend to run the system in question with a rich collection of
>resource limits active to prevent such accidents from killing the box.
>It's the only way to go. :-)

"Prevent" is the wrong word :-( "Reduce the incidence of"! If those
students do a significant amount of Intternet programming, then there
are plenty of resources which are not covered by such limits on any
Unix I know.

But I assume that you are aware of that ....

Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email: nmm1@cam.ac.uk
Tel.: +44 1223 334761 Fax: +44 1223 334679

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