On Fri, Feb 08, 2002 at 12:28:44PM +0100, Bart De Schuymer wrote:

> > Just for the heck of it, after I added the static ARP entry,
> > I also tried adding a route (ip route add 198.122.149.10 dev
> > eth0), which I did not have
> > before (since ip forwarding is disabled, of course).  As
> > soon as it received
> > the packet to be DNAT'd, I immediately got a kernel panic
> > error and had to restart the system.  I also tried adding
> > this ip route without the static ARP
> > entry in place, and got another kernel panic error.
> 
> After looking at the bridge/netfilter patch (and doing some tests) it seems
> that DNAT'ed packets in the bridge are always/sometimes (?) routed. This
> because the destination MAC address is set to that of the bridge device.
> So it doesn't work because you didn't put ip_forward on.
> See: net/bridge/br_netfilter.c:br_nf_pre_routing_finish().
> "memcpy(skb->mac.ethernet->h_dest, dev->dev_addr, ETH_ALEN);"
> 
> If this is considered a feature or a bug I leave up to Lennert.

Well.. the crashing bit is a bug of course ;)

The only interface we have for calculating a new route in the
case of doing DNAT to a different bridge port group is
ip_route_input (and if you look at it technically, in this
case it does become routing and isn't really bridging anymore).

So I think all we can do is throw our hands up in the air and
drop the packet.


cheers,
Lennert
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