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From: Jung-uk Kim <jkim@FreeBSD.org>
Date: Fri, 18 Jul 2008 19:07:26 -0400
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Subject: [Qemu-devel] Re: [PATCH] networking using libpcap
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To: Sebastian Herbszt <herbszt@gmx.de>
Cc: Juergen Lock <nox@jelal.kn-bremen.de>, qemu-devel@nongnu.org

On Friday 18 July 2008 04:39 pm, Jung-uk Kim wrote:
> On Friday 18 July 2008 12:12 pm, Sebastian Herbszt wrote:
> > Using pcap_setfilter helps and colinux (conet-bridged-daemon)
> > does use one too. Currently your filter is
> > "ether dst 52:54:00:12:34:56 or ((broadcast or multicast) and not
> > ether src 52:54:00:12:34:56)". The filter used by colinux is
> > "(ether dst 00:ff:81:24:00:00) or (ether broadcast or multicast)
> > or (ip broadcast or multicast)".
> >
> > The "and not ether src 52:54:00:12:34:56" part in your filter
> > prevents the VM from seeing own packets. It doesn't reply to own
> > "ping broadcast" where it does in colinux and VMware Server.
>
> I knew that I might have missed some edge cases. ;-P Corrected and
> enabled by default.

I simplified the filter as:

"ether dst <MAC_ADDR> or multicast"

because we are only interested in Ethernet packets and broadcast 
address is a special multicast address.  Any upper layer protocols 
must be encapsulated in one of these forms.  For example:

http://www-uxsup.csx.cam.ac.uk/courses/ipv6_basics/x84.html

Jung-uk Kim