I was looking for a connector to piggy back the wires of a rj-45 cable. it cant cut the wires, but rather clip onto it.
I would have to strip the outer shielding exposing the inner wire and then just clip each bit on the corresponding colour wire...

Anyone got ant ideas?

I don't think there's such thing.

Why would you want to do this anyway? You can't have two computers on the same wire... (unless only one was switched on at a time)

I'm sure there is...

Yes they can actually, I'm doing it all passively. I have done it before.

Ok then. I can't say I've seen anything like it though - RS and Farnell don't stock anything like it. I can't think of where else would sell them.

Sounds like a handy spy gadget to me. They work by inducing a tiny current in the coil surrounding each wire. It's the same principle used to passively measure amperage in power lines.

I have no idea where you might buy one, but it would make a great electronics project to build one. I'll add it to my list...

Yeah tzar i was thinking the same thing. I was up till 3am looking but bo luck!

On the making factor, how would you do about doing that? i have a vague idea but not much. But any help would be good..

The simplest method is to wrap a small coil of wire around one of the wires, and amplifying the output. In fact, connecting the coil in place of an audio cassette head might form a pretty good amplifier for tapping telephones.

Since you're tapping digital signals, you'll need a 1-bit comparator to clean up the signal.

Another method is to use hall-effect sensors. Simply place them next to a wire, and read the output. Some even have built-in amplifiers and comparators. They might even work without removing the outer insulation. Place a tight ring of a dozen or so sensors around the cable, and measure the relative voltages of each. Ethernet uses balanced signal pairs, but the sensors closest to each wire will still be able to pick up some difference.

I have some analog hall-effect sensors, so hopefully I'll get around to trying this soon.

The wires are twisted together, thus effectively making a common mode rejection circuit to any listening devices. You will need a very small receiver to pick up any signals. A Hall sensor might work (and I stress "might" very much), and you will need to adjust it to get a good signal.

Clipping or unhooking it and placing a splitter will be a better solution, though.

And, no, only one computer can use any port of any router at one time. You can sniff traffic using ethereal, but you cannot use it.

I also forgot to mention that the signal connections are half-duplex, so you will need some sort of rejection circuit to amplify the signal so it can only pick up the stronger signal, rejecting the other, and send that to whatever listening device you have. The same for the other line on the other side of the cable.

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yeah i was thinking passive Arp poisoning, the network i want to monitor keeps blocking my laptop from connecting. i think it has a radius server. i just want to be able to get the mac and ip of a legit computer and the only place where i can get to the cable is in the roof and i cant cut the cable or thy will find it....

i THINK if u go to radio shack or circut city and tell them what u need, they can help u. IF they r screwing u over (who ever bumped ur laptop from the net - then take cable cutters and cut the cable in places people will never find the broken cable.