I'm not sure what you're asking here, but at every US airport, you have to go through TSA to get to any gate. If you're coming into BOS on an international flight and connecting to a domestic flight, you go through standard TSA security after you clear Customs. If you have some duty-free liquids in the sealed bags, they can go through the checkpoint as a carry-on item. Otherwise, it's like going to the airport for a domestic flight. Pre-Check if you have it, etc.