Great Scott Gadgets Throwing Star LAN Tap Kit User manual

The Great Scott Gadgets Throwing Star LAN Tap is a small, simple device for monitoring Ethernet
communications. These instructions will help you assemble and use your Throwing Star LAN Tap.
GREATSCOTTGADGETS
ThrowingStar LAN Tap Kit Instr ctions
1. Gather the components. You should have one Throwing Star LAN Tap
printed circuit board, four Amphenol RJHSE5080 modular connectors,
and two 220 pF capacitors with 0.1 inch lead spacing such as the
Xicon 14050P2221KRC. You will also need a soldering iron,
some electrical solder, and a pair of wire cutters.
2. Insert the four modular connectors (J1, J2, J3, and J4) into the
printed circuit board. Be careful that each of the leads extends
through the circuit board before snapping the connector fully into place.
3. Solder the eight leads of each connector.
4. Insert the two capacitors (C1 and C2) through the circuit board. It is helpful to
slightly bend the leads on the underside of the board so that the capacitors stay in place
when the board is turned over.
5. Solder both leads of each capacitor and clip off the excess with wire cutters.
6. Clean the flux from the board. Depending on the type of solder used, you might need
water, alcohol, or other solvents. A toothbrush can make this job easier. Allow the board
to dry before use.
Assembly
SolderingTips
The Throwing Star LAN Tap Kit is an excellent starter project if you have never soldered before!
1. Keep your soldering
iron tip clean with a wet
sponge or brass sponge.
2. Apply a small amount
of solder to the tip of your
hot iron to promote heat
transfer.
3. Hold the side of the
iron near the tip against
the joint to be soldered.
4. Feed solder into the
joint, not into the iron

Usage
1. Use Ethernet cables to connect the
Throwing Star LAN Tap (J1 and J2) in line
with a target network to be monitored.
2. Use Ethernet cables to connect one or both
of the monitoring ports (J3 and J4) to ports
on one or two monitoring stations. Each port
monitors traffic in one direction only.
3. Use your favorite software (e.g., tcpdump
or Wireshark) on the monitoring station(s) to
capture network traffic.
More Information
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.
The Throwing Star LAN Tap is designed to monitor 10BASET and 100BASETX networks. It is not
possible for an unpowered tap to perform monitoring of 1000BASET (Gigabit Ethernet) networks, so the
Throwing Star LAN Tap intentionally degrades the quality of 1000BASET target networks, forcing them
to negotiate a lower speed (typically 100BASETX) that can be passively monitored. This is the purpose of
the two capacitors (C1 and C2).
Like all passive LAN Taps, the Throwing Star LAN Tap degrades signal quality to some extent. Except as
described above for Gigabit networks, this rarely causes problems on the target network. In situations where
very long cables are in use, the signal degradation could reduce network performance. It is a good practice
to use cables that are not any longer than necessary.
Theory of Operation
For open source design files and additional information, including the most recent version of this document,
visit:
http://greatscottgadgets.com/throwingstar/ r1d3