From owner-freebsd-net@FreeBSD.ORG  Sun May 29 23:19:27 2011
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Date: Sun, 29 May 2011 15:43:22 -0700
From: Yuri <yuri@rawbw.com>
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Subject: MAC address conflict causes 8.2-STABLE to freeze
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I had a bug in my setup script that was setting the same MAC address to 
several computers. This situation of course is not normal and should not 
normally occur.

But I noticed the side effect that causes me to worry:
8.2-STABLE host was periodically freezing in such situation.

My understanding is that such situation will cause all packets sent to 
this MAC address be accepted by every host in conflict and for example 
many garbage TCP packets will arrive to each machine. But why should it 
freeze the system?

It looks like there is some bug in the code rejecting garbage traffic 
and my setup exposed it.

This could also be a security issue when some other host on the same 
network can cause FreeBSD to freeze by sending some rogue packets to it.

I should also note that I am talking about the wireless device ath0 and 
passwordless WEP network.

Yuri