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Building a Network Tap

This time not software,its hardware stuff

What is a Network tap ? 
   A Network TAP (Terminal Access Point) denotes a system which monitors events on a local network and in order to aid administrators (or attackers) in analyzing the network.The tap itself is typically a dedicated hardware device, which provides a way to access the data flowing across a computer network. In many cases, it is desirable for a third party to monitor the traffic between two points in the network
                                                                       --- From Wikipedia
Application:
  • Troubleshooting Network 
  • IDS (Intrusion detection system)
  • Packet sniffing
  • and More...

How to create one ?
    Here we will learn how to build a network tap for cat5 series cable ( Ethernet cables ). Things you need to create a network tap
  • 2 Ethernet cables ( There are two types of cable 568A,568B choose same type of cable )
  • Wire Cutter

Once you got everything cut the wire into half then you can able to see 4 twisted pair ( 4 pairs , 8 wires ) Here orange twisted pair and green twisted pair are important

orange twisted pair -> send data
green twisted pair -> receive data

when you cut the both wire into half you got four wire for easy understanding i will use wire 1,wire 2,wire 3 and wire 4

In wire 1, carefully untwist the wire of orange and green and cut the strip ( you will see the copper wire )  do the same thing to wire 2 for wire 3 and 4 you can untwisted green pair alone

Join the wire 2 orange pair to wire 1 pair and wire 2 green pair to wire 1 green pair

For Transmit tap ( to listen the transferred packets from the network )
 connect the green pair of wire 3 to the orange pair of the wire 1 and wire 2 ( orange wire is responsible for sending data when we hook up with green wire i.e receiving wire we can able to see the packet it is sending to the other network )

For Receiving tap ( to listen to the receiving packets from the network )
 connect the green pair of wire 4 to the green pair of wire 1 and wire 2 ( we know the green wire receive data so hook up to it we will able to see the packets network is receiving )



To cover the connection between the wires you can use Heat shrink tube or cello tape the final result will be somewhat similar to this


To check whether the system is working
  •  connect wire1 connector to the switch and wire 2 to the victim machine
  • connect either wire 3 or wire 4 in another pc ( pc running linux is better )
  • set the configuration of the wire 3 connected pc to promisc mode ( mode which allow you to listen to all the packet in the network ) 
  • In linux terminal type ip link set eth0 promisc on
  • To verify the eth0 ( ethernet device - name may differ in your system ) type ifconfig
  • Open up your sniffer ( i use wireshark ) then select eth0 in wire 3 connected linux pc you can able see the packet in the network


cheers you learn how to do it 


Thanks to
Joseph ( My senior who helped me in doing this project )


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