Thanks, I think I understand now. Any idea of the cheapest kind of switch that will do this?

It’s actually a DVR connected to 6 cameras, but the DVR physically resides in a neighbor’s garage (long story). I’m concerned someone in the neighbor’s garage could potentially disconnect the cable, plug in an unmanaged switch and put the DVR in the switch, then use my internet connection for potentially illegal activity - so I want to make sure that only the DVR can actually access my network from the wire and absolutely nothing else.