Authentication

I'm rather unsure in what category this belongs and what skills are needed for this. Basically, there's a program that, upon using requires information from a remote server before it works. I'd like to have a program that can mimic this information, tricking the program into working. Shouldn't be too hard of a project I presume. At this point I time, I think if you can just capture the package that the server sends to the program just once, create somewhat of a loop and use that every time the program asks for it, it should be sufficient. But then again, what do I know..