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Re: [libvirt] [PATCH 9/9] add DHCP snooping support to nwfilter



"Daniel P. Berrange" <berrange redhat com> wrote on 05/10/2011 02:28:25 
AM:

> From: "Daniel P. Berrange" <berrange redhat com>
> To: David Stevens/Beaverton/IBM IBMUS
> Cc: libvirt-list redhat com
> Date: 05/10/2011 02:32 AM
> Subject: Re: [libvirt] [PATCH 9/9] add DHCP snooping support to nwfilter
> 
> On Mon, May 09, 2011 at 01:12:10PM -0700, David L Stevens wrote:
> > This patch removes remaining pieces of IP address learning.
> 
> Do we actually want todo this ?  This is effectively causing a
> regression in functionality for anyone who's relying on the
> current IP learning support, but who does not use DHCP.

        I think there is no security at all in believing a guest's notion
of what its own IP address is. Static addresses can still be used, but
I don't see the point of allowing a guest to choose which address it
can use (including a spoof address) and doing any filtering at all.
        I didn't include it in this set, but implicit in using DHCP
snooping is having a list of trusted DHCP servers. As that is just
an ordinary filter addition in examples with no (non-XML) code
changes, I thought I'd get this discussion kicked off first.
        Patches I had in mind but didn't include here:

p10 - add support for multiple MAC addresses via comma-separated lists
        (e.g., support '54:0:0:0:0:0:1,54:1:2:3:4:5' as a MAC 
specification)
p11 - add support for multiple static IP addresses via comma-separated
        lists
p12 - add a filter in examples/xml/nwfilter for dropping DHCP server
        traffic not in a trusted list.

                                                                +-DLS


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