The Throwing Star LAN Tap is a passive Ethernet tap, requiring no power for operation. There are active methods of tapping Ethernet connections (e.g., a mirror port on a switch), but none can beat passive taps for portability. To the target network, the Throwing Star LAN Tap looks just like a section of cable, but the wires in the cable extend to the monitoring ports in addition to connecting one target port to the other.
The monitoring ports (J3 and J4) are receive-only; they connect to the receive data lines on the monitoring station but do not connect to the station’s transmit lines. This makes it impossible for the monitoring station to accidentally transmit data packets onto the target network.