Alright, I've come across a little programming/networking challenge while helping a friend out recently, so I'll cut right to it.

Develop a [hopefully simple] protocall/simple as possible program, in any self contained form to let two [basically default install] Windows 2k pro computers communicate over a network with the following restrictions (seems easy so far duh..):

- Done in unpriveleged user mode.
- No WinMessenger broadcasts, don't want every user on the network bothered with it.
- leave the smalles possibility of the hosts getting picked up by a port scan when listening(possibly only listen for short times)
- few as possible files to keep up with and no traces left behind.

As you've probably figured, I'm trying to communicate secretly on a network. All I'm trying to come up with is a way to do it with as high a degree of secrecy as possible. As you also might have guessed, this is for use on a school network... well, that's what he wants anyways. I'm just trying to think of a way to do it, I probably won't give it to him. You know, make him figure it out himself or something. Plus, I'd then like to just play around with detecting that exchange anyways, just for fun.

All I need is a concept, no source or anything, that's my problem if I ever actually feel like putting it together. I'll let you know if I think something up.

Edit: Also, the data stream is not important, duh, I'll just pop on some encryption or whatever if I'm worried about that, the biggest problem is a constantly listening port if you get my idea here.