Not quite sure what you mean but have you tried forward chain IP firewall filter rules? They manage traffic just fine 98% of the time.
If they do not work there is such a thing as Bridge firewall rules - but they are for advanced users and unique circumstances
The network is spread across a city and lacks firewall. I need to add routers solely to add firewall at specific points in the network. The only traffic on the router will be over an ip-bride on two ports. I need to limit the traffic allowed so that only traffic from specific IPs is passing over the bride.