According to one aspect, a communications system for sending a data packet, including a first device, comprising a processor, the processor configured to compose an addressing bitmask and, address the data packet with the bitmask; and, a transmitter connected to the processor for transmitting the addressed data packet; and a second device, comprising a receiver for receiving the addressed data packet; and a processor attached to the receiver, the processor configured to perform a bitmask test on the bitmask contained in the addressed data packet such that, if the test is failed, then the addressed data packet is discarded.