Linux Repeater

Hello,

I have a linux box which I would like modify to work as a repeater.
It has a cardbus network card and normal pci nic rj45.

Reason is that I have a wireless internet connection and in the internal
network I have a wireless router fw which I would like to connect directly
to my public ip.
This wireless router can only be connected via rj45 jack.

Earlier I has my linux box as a firewall-router, but I do not want to have
two routers in my network.

I tried to look software repeaters, I found Stone, but it seems that it
cannot simply forward all traffic between interfaces, just one port at the
time.

Is there a simple tcp/ip repeater that would hardwire two interfaces
together just repeating all traffic between them?
Is it still possible to use FreeS/Wan ipsec together with that (in the same
linux box)?

Current status:
Internet - Linuxbox/vpn/gw - 192.168.2.* - WLAN router - 192.168.10.*

Desired:
Internet - Linuxbox/vpn/rptr(?) - WLAN router/fw - 192.168.2.*


-Pekka