DNATing packets travelling over a bridge

Hi,

I have a transparent firewall to the internet setup using ebtables
with a transparent bridge between two ethernet interfaces.  Neither of
the two interfaces nor the bridge have an IP address assigned.

I am adding a third network card to the firewall that will be
connected directly to another computer.  The third network card and
the other computer will be on a subnetwork of their own (not part of
the bridge)

What I would like to do is redirect some of the outgoing firewall
traffic to the other computer without the internal clients having any
configuration changes.

My first idea of the setup:

REDIRECT_IP=1.2.3.4
INTERNAL_IP=192.168.0.10

iptables -t nat -A PREROUTING -d $REDIRECT_IP -j DNAT --to-destination
$INTERNAL_IP

This way any packet coming from the internal LAN destined for 1.2.3.4
will transparently be redirected to my second computer running on
192.168.0.10.

I also want the response packet's source address to be re-written to
1.2.3.4 so the client doesn't need to know that the IP was redirected.

Will this work on a transparent bridge setup?

Thanks,

Mike

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