Re: Crashing Unix

From: Douglas Siebert (dsiebert@excisethis.khamsin.net)
Date: 03/16/02 

From: dsiebert@excisethis.khamsin.net (Douglas Siebert)
Date: Fri, 15 Mar 2002 23:59:04 +0000 (UTC)

"Nick" <goonerbloke_nospam_@hotmail.com> writes:

>I am a newcomer to Unix and only have very limited knowledge and experience
>of it.
>I am being taught Unix at University and during one lecture, the lecturer
>kept going on about us crashing it and he seemed disappointed that no-one
>managed it.

>Is there any kind of script or combination of commands that will crash Unix
>on a network? We cannot access the internet from our Unix server and using
>ftp between Windows & Unix is the only method of file transfer.

>I don't want to permanently screw up the system, just make it crash to see
>how it can be done.

Well, on recent versions of Linux:

echo 1 > /proc/sys/kernel/panic

This isn't really "crashing" as such since this is a way to deliberate
cause it to crash for testing purposes, but the net effect is the same.
Just about any Unix will crash if you write random data in /dev/kmem.
You must be root for either of these methods to work.

The trick is to find ways to crash it as a normal user. More difficult,
but doable (can't point to anything offhand though) There used to be
a program called 'crashme' floating around the net that executed random
syscalls and random code and was able to crash pretty much any Unix
system, given enough time. I think it was used as a way to detect bad
conditions and improve the robustness of the kernel, so it may no longer
work, at least on some systems. Haven't tried it in about 10 years.

There was a bug a few years back called the "ping of death" that was
able to crash a large variety of systems (many Unixes, Windows, even
some network devices like routers, switches, etc.) that was particularly
bad since someone could crash a system on the other side of the world
and all they needed was to be able to send a 'ping' packet to it. That
bug was quickly fixed after it became known, needless to say :) 

--
Douglas Siebert                          dsiebert@excisethis.khamsin.net

A good friend will help you move, a true friend will help you move a body.

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