[Xen-devel] Re: [Fedora-xen] IP addresses used by domU

[Daniel P. Berrange]

On Thu, Sep 21, 2006 at 10:50:11AM -0700, Sanjam Garg wrote:
> thanks a lot.
>   
>  Your assumption on bridging was correct...but the fact is that i  
> cant use sniffing to make a guess as my system has constraints laid 
>  down by the intentions of the user who may use some packet source 
> IP  spoofing to mislead dom0.if thats all that can be done then i
> would  need to do something more rigrous...

When using bridging the network security concerns are pretty much exactly 
the same for those of a bare metal machine - the whole point of bridging
is that the guest is connecting directly to the LAN as any physical machine
would. 

Thus if you don't trust the admin of the DomU then don't let them connect straight
to the network. For example, you can switch Xen to an alternative networking
config where DomU's have to be forwarded & NAT'd using IPTables to get LAN 
access.  If you really want to use bridging I guess you could try filtering
out any traffic from the DomU's particular vif which has an unexpected
source IP address, but really best bet is to go for NAT & remove their 
direct access


Dan.
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