netdev - Re: [PATCH] bridge: make bridge-nf-call-*tables default configurable

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Date:	Wed, 1 Jul 2009 12:10:35 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Jan Engelhardt <jengelh@...ozas.de>
Cc:	David Miller <davem@...emloft.net>, markmc@...hat.com,
	netdev@...r.kernel.org, kaber@...sh.net,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH] bridge: make bridge-nf-call-*tables default
	configurable

On Wed, Jul 01, 2009 at 05:50:18AM +0200, Jan Engelhardt wrote:
> 
> On secondary thought, one could also argue that because conntrack 
> ignores the interface, two unrelated connections happening to be routed 
> through the same machine(*) are tracked as one, too.

Good point.  We really should make these risks much more explicit.

However, I still think the risk with bridging is higher, especially
in the presence of virtualisation.  Consider the scenario where you
have to VMs on the one host, each with a dedicated bridge with the
intention that neither should know anything about the other's
traffic.

With conntrack running as part of bridging, the traffic can now
cross over which is a serious security hole.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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