I think it is accepted knowledge that packet traveling in the same subnet are handled by the switch. However, my question is is there some way to control these packets? Possibly through arptables, ebtables, PREROUTING in iptables (may not ever get here that's a question also). For instance how does the switch and/or router know that two machines are even in the same subnet to begin with? There must be a way to distinguish and manipulate this traffic. Can someone answer these questions?