[Bridge] [PATCH net] bridge: ebtables: fix reception of frames DNAT-ed to bridge device

Pablo Neira Ayuso pablo at netfilter.org
Wed Mar 15 10:42:11 UTC 2017


On Wed, Mar 15, 2017 at 11:26:08AM +0100, Florian Westphal wrote:
> Linus Lüssing <linus.luessing at c0d3.blue> wrote:
> > When trying to redirect bridged frames to the bridge device itself
> > via the ebtables nat-prerouting chain and the dnat target then this
> > currently fails:
> > 
> > The ethernet destination of the frame is dnat'ed to the MAC address of
> > the bridge itself just fine and the correctly altered frame can even
> > be captured via a tcpdump on br0 (with or without promisc mode).
> >
> > However, the IP code drops it in the beginning of ip_input.c/ip_rcv()
> > as the dnat target did not update the skb->pkt_type.
> 
> Right, thats the reason why ebtables also has ebt_redirect target
> which does this pkt_type fixup.

I'm missing then why redirect is not then just enough for Linus usecase.


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