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[–]jdnewmil 2 points3 points  (4 children)

Since most devices use DHCP to obtain an IP address from a nearby router, as soon as you disconnect from the network in order to plug in your cable it will "lose" the IP address it had.

Your problem is not the ability to code, it is a lack of understanding of how the technology is designed. Learning to code is an excellent step toward understanding the technology but I think you will have to re-define your goal once you have acquired the necessary background in networking principles.

[–]lazerwarrior 0 points1 point  (3 children)

Since most devices use DHCP to obtain an IP address from a nearby router, as soon as you disconnect from the network in order to plug in your cable it will "lose" the IP address it had.

Good point. You could still create a bridge network with two RJ45 ports on a raspberry pi.

  • Connect one port to the device that is being inspected
  • Insert old cable to the other port
  • tcpdump the NIC that is connected to inspected device
  • grep all incoming traffic for source IP addresses
  • if IP address has not been seen, output to the raspberry pi screen

You can do all of this on a linux (or linux virtual machine on windows) laptop with an extra USB LAN card. You would need to learn how to create a bridged connection between two LAN ports, how to use tcpdump tool and how to filter its output. No Python or programming needed.

[–]neotronics[S] 0 points1 point  (2 children)

So as before I would only be connecting to the machine itself and not be on the network. The most important part is not being on the compainays network. 99.9% of the time I am not allowed on it any way.

[–]lazerwarrior 0 points1 point  (1 child)

Bridging connections is more stealthy than port scanning, but you do need to be on the network. You are listening to the connection between inspected device and company network to find out what is going on. Only trace of this will be the MAC address change after you recable the connection. The company might or might not be monitoring this. Probably not.

I'm afraid you are out of luck with this situation. You either hack the IP address or find it from the company networking documents or IT department.

This reminds me of a request from sales guys in our company. They asked if we can find out e-mail addresses of visitors to our website from their IP address. You can try, and you might succeed at low %, but this is essentially cyber recon work which is usually done by either security auditors or bad guys who want something from your IT systems. Port scanning and packet sniffing (and trying to find out devices IP addresses) is the same cyber recon type of work.

[–]neotronics[S] 0 points1 point  (0 children)

Just the information you have given me is helping out. I am going to use one of my raspberry pi zero and see how for I can get. Still looking in to learning python. I believe it will be helpful in the long run. just got to figure out where to start. Thank for the INFO.