UDP IP Filtering ??

First of all hello, I'm sorry that my first post has to be a question but I've been working on this for a couple days in my spare time and haven't gotten it up yet.

I'm basically developing an AC (anticheat) system just for the fun of it, and knowing how ACs work and what they fail at/do not attempt to do I've made a pretty good client, and I got up the server no problem. It was very fun to learn how to do it and such, but now I'm stuck at a point..

Basically I have a GameServer.exe which is listening on a certain UDP port, and I need to find out when a foreign IP connects to that port, or the process, or whichever. So far I've tried many things but it usually ends up in a WSAEADDRINUSE, and I tried hooking send/recv on the program but am unsure on how or even if I could get the ipaddress, and might not be possible unless its using sendto/recvfrom because it has the ip struct. I have a pretty good lite firewall going with only a few lines of code using the Packet API (PfAddFiltersToInterface). Basically I need some help, and I don't want to do anything sloppy like filter the log file for ip address connections. If it comes to that, I will do it thou lol.