[LARTC] mark incoming traffic

[Bgs]

  Greetings,

I'd like to mark incoming traffic based on TOS to use the mar for 
backtraffic routing. I have two gateways on the same net and incoming 
traffic may arrive from any of them. I want the return packets to go the 
same way. My plan is:

Normal traffic goes through default gw. Traffic from the other has TOS 
0x08 set. I'd like to mark traffic with TOS and use fwmark awith iproute 
for outbound packets.

My problem is that I can mark based on an incoming property and I need 
the mark on the outbound packets. How can I do this?

Doing "-A INPUT -p tcp -m tos --tos 0x08 -j MARK --set-mark 1" (in 
mangle of course) is not good as the mark is lost. Doing tests with "-A 
OUTPUT -p tcp -d test_client_ip -j MARK --set-mark 1" works ok.

Is there a solution?

Thanks in advance
Bgs