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Date: Fri, 24 Mar 2006 13:48:59 +0300
From: Eygene Ryabinkin <rea-fbsd@rea.mbslab.kiae.ru>
To: Jon Otterholm <jon.otterholm@ide.resurscentrum.se>
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Cc: freebsd-net@freebsd.org
Subject: Re: How do you keep users from stealing other user's ip??
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> To prevent users from MAC-spoofing - buy a switch with some kind of 
> "port-security". If you could lock down a port to just one MAC and have a 
> static ARP on the router it would be pretty hard to spoof the MAC-address. With 
> another MAC than the one associated with the port you simply will not be able 
> to talk to anyone.
 No-no-no, it is _very_ easy to spoof MAC address. For FreeBSD it is just
'ifconfig em0 link 00:11:22:33:44:55'. Almost the same for Linux and
pretty easy for Windows. Port security would not prevent MAC spoofing --
you can not rely on the MAC provided by computer since it is easy to
determine one for the 'trusted' machine and set yours to that.
-- 
Eygene