can netfilter capture internal network packet?

["calvin" <calvinproject@xxxxxxxxxxx>]

Dear all,

I got a serious problem with my netfilter programe.

what i am trying to do is capture a packet frmo A to B in the same network
and direct it to QUEUE.

My setup is

A      B
 \       /
  \     /
  HUB
     | (eth0)
   GW
     |(eth1)
     |
     |

is that possible to: when A send a message to B port 1700 (for example) ,
the iptales in GW can grep the packet and put into queue for processing and
put it back to the line?
I tried to the rules like:
iptables -A INPUT -i eth0 -p udp --dport 17-- -j QUEUE
or
iptables -A INPUT -o eth1 -p udp --dport 17-- -j QUEUE
or both of them.

I can get it works.

I also have a netfilter module, insepecting packetsrc/dest port in the
PRE_ROUTING hook point, also can't get it.

is that any way I can do what I want to do in module? in iptables?

Thanks very much for any of your help..

Regards,
Calvin