Sharing Internet Connections (O'ReillyNet)
O'ReillyNet covers
the use of fwbuilder on FreeBSD. "
Before creating the rules you need within fwbuilder to share your internet connection, make sure that your network is properly set up. The computer running fwbuilder needs to have a NIC, which it uses to communicate with the other computers in your home network. This NIC is separate from the hardware you use to communicate with your ISP; that might also be a NIC (in the case of a cable or DSL connection) or it might be a modem (in the case of a dial-up PPP connection). Make sure the NIC you use to communicate with your other computers is plugged into the same hub or switch as your other computers."