I am trying to find a way to filter tcp port numbers between two interfaces without setting ip address on the interfaces so that the router is basically invisible to the network so that I do not have to change my ip scheme. I have tried to setup a bridged interface and use /ip firewall to filter the traffic between the interfaces in the bridge, I am not sure if the software can even do this since I assume the bridge is only opening the packets to layer 3 since the standard bridge firewall only firewalls to ip address and not port numbers at layer 4. If any one knows a way to do this or another way to make it work with mikrotik software please let me know, thanks for any help.