Often there's just a pair of wires/pins into a chip that you use to control the chip, for a NIC, modem, radio, what have you - accompanying this is a protocol y

Often there's just a pair of wires/pins into a chip that you use to control the chip, for a NIC, modem, radio, what have you - accompanying this is a protocol you use to comminicate with the chip. For e.g. a NIC, it's not that many things that need to go wrong when you encapsulate a packet it should forward out on the wire so it rather looks like a control packet triggering some undesired results on the chip. Or vice versa.