How to simulate the data of someone else's computer on your own?

Question

proxy

The task is as follows
. I have 2 computers, mine and a friend, and a program that determines who enters the network. The parameters by which she judges are unknown, but I plan to start with the banal, the same ip address. A friend has access to this network, I don’t have it, can I configure it so that I can have the ip address of a friend’s computer. I thought Hamach would help, but it didn’t (I’m a layman, I have general knowledge). I was looking for how to make a proxy server from a friend's computer, I found a long instruction, but install both programs, one installs the server, the other does not connect to it.
So, you need to find a solution, for starters by ip, if anyone has experience in simulating iron, if this is possible, share it, I would be grateful.
PS if someone knows the answer, please write in detail, because I'm still just getting it right, I want to understand in detail how it works.