i have a problem. Im in a network security class at school and we are supposed to hack the class room network. The more imgainative (sneaky) way you do it the better grade you get. now i have a great idea to do it but im having trouble. i need to make a device that i can clip to CAT5 cable strands and tell me which line it is. weither its TX+,TX-,RC+, or RC-. now iv tried doing it by going through the wires in an orderly maner but im never sure when i have the right conections. id like a device that i could clip to the individual strands of the cable and have it tell me which strand it is (one strand at a time) or clip it to all the strands (one clip per strand) and have it tell me if its the correct combination. is there a way to do this. Id love to crack this network in a way iv never seen done before. I have access to the wire order of the cables but i dont want to use it because then i cant claim that this is a tactic that can be used by outsiders. Any help would be apreciated.
I'm prety sure you could buy a CAT5 network tester, i'm sure i've seen a fancy one with an LCD that can do what you want.
i have a basic tester but it requiers an RJ45 end be put on the cable. and that needs to be wierd correctly. i was hoping to build a device that uses gator clips.
Well you could snip a RJ45 cable, stick gators on the ends of the strands then plug that into the tester?
yeah but it only reads the electrical impulses off the line to tell me if its live or not it doesnt tewll me if its TX+ TX- RC+ or RC- which is what i need to know. I REALLY appriciate all the help you guys are giving me. iv been trying to figure this out for a while but keep getting stumped.
I'm no netwrok god, but you get this to work in practical terms you must find some form of measurable difference bettween each line a resistance, a P.D. when conncted, etc.
are you allowed to cut the cable mid way or is there to be minimal damage after you've done your bussiness... there are a couple of decent ways to do it.. it would be much better if the cable is not perminantly damaged so as to be able to get back to the same point again should you wish.... a nice idea would be to atatch a WiFi access point and use a lappy... but for the identity of the cables what you would want is maybe some kind of linemans handset type thing... the kind that allows you to ping from it as well... confirming whether you got it right... i'll try and have a think of more things that i would do in a bit... but i'm meant to be working somewhat..
what i was planing is to finger nail steip some of the ionsulation off in different parts of the wire strands and connect the gator clips. i dont want to cut it cuz that would show intrusion onto the media and my instructor wouldnt like that. im not sure if connectiong a device (ie laptop) to the cable with the wrong strands hooked up would damage the device and i dont want to do that. it would be expensive. thanks again for all the thought and effort guys
Problem one is to fing the 4 active wires, then you need to figure out TX and RX pairs. Maybe you could do this by looking at the IPs in thde headers of the packets. You are going to have to look up BMC aka biphase mark code, as well as any other hardware specific ethernet stuff, decode that into packets and then decode the packets, but once done, long term behavior of the RX line should be the the pair with the destination machine's IP in the packets. If the network is using switches, it will be pretty easy. I it is all a bunch of hubs, then it might be a bit more difficult. I would imagine that you would need to compair outgoing vs incoming. If a packet appears on one line, and then immediatly on another, look at the order of appearence. If multiple packets happen like that, then you can match TX and RX up. Or maybe you could use the signaling for packet collisions on a hub based network to sort it out. Oh yea, if polarities are reversed, then you have negatice voltages. That should be easy enough to figure out. The final thing that if the network is properly wires, TX is always a pair like orage and wither w/ oraqge stripe. I hope you found/find some of my babling useful.
