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Date: Thu, 15 Jan 2009 00:06:40 +0200
From: Dor Laor <dlaor@redhat.com>
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Subject: Re: [Qemu-devel] Re: [PATCH 1/5] virtio-net: Allow setting the MAC
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To: qemu-devel@nongnu.org
Cc: Mark McLoughlin <markmc@redhat.com>, kvm <kvm@vger.kernel.org>

Jamie Lokier wrote:
> Alex Williamson wrote:
>   
>>> What if the guest will chose the host's mac?
>>> Thinking about it, I don't think we should test that.
>>> A concerned host mgmt app can add ebtables roles for such a case.
>>>
>>> Maybe we can optionally allow/deny it?
>>>       
>> What's the topology you're thinking of that the virtio-net MAC is also
>> the host MAC?  I typically use a bridge with a tap device, so the
>> virtio-net MAC is isolated from the host.  Thanks,
>>     
>
> For example you might forward IPX packets to the guest and IP/ARP to
> the host, using an ebtables rule to distinguish them.  From the
> outside, it would look equivalent to a single host processing both IPX
> and IP.
>
> -- Jamie
>
>   
That's a nice common scenario ;)
What I meant is that if we allow the guest to change his mac address, it 
can deliberately
change it to other hosts/guests mac and thus create networking problems.
Although guest can always mangle packets, maybe it worth enforcing these 
macs for the guest.

Thanks,
Dor