Re: [LARTC] routing to two interfaces

[Robert Felber <robtone@gmx.de>]

On Wed, Nov 20, 2002 at 11:55:37PM +0100, Paco Brufal wrote:
> 	I have a linux box with 3 interfaces, 2 of them have public IPs
> (eth1 and eth2), and the third is a private IP (our LAN). I want to do the
> following: if a packet is coming from eth1, it must be forwarded to eth0,
> and when it comes back, it must be routed to eth1. In case of packet comes
> from eth2, it must be forwarded to eth0, and the respose must be routed to
> eth2. In other words, a packet must leave our network by the interface it
> come.

try out following:
it's just an idea and i didn't try it out

# delete tables 2 and 3 to avoid duplicates
# add for each table the gateway to use
$IP route del table 2
$IP route add table 2 via $ETH1_GATEWAY_IP dev eth1
$IP route del table 3
$IP route add table 3 via $ETH2_GATEWAY_IP dev eth2 

# mark each packet regarding to its incomming device
$IPTABLES -t mangle -A INPUT -i eth1 -j MARK --set-mark 2
$IPTABLES -t mangle -A INPUT -i eth2 -j MARK --set-mark 3

# delete to avoid duplicates
# lookup the right table regarding to packets fwmark setting
# flush the routing cache
$IP rule del fwmark 2 table 2
$IP rule del fwmark 3 table 3
$IP rule add fwmark 2 table 2
$IP rule add fwmark 3 table 3
$IP route flush cache


--
rob
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