(Cross post from stackoverflow)

I am creating a multiplayer 2D game for Mac and iOS devices. I'll be using cocso2d for graphics/game engine, however I am largely blank on what to use for multiplayer communication. Please note that I cannot use central severs e.g. SmartFox, RedDwarf, etc since I want the players to "host" games for others and be able to play it on their LAN, VPN or my own servers.

Any pointers? I checked lidgren but it's for .NET only and hence not an option for me.

EDIT: just in case it wasn't clear, the messaging has to be real time hence it's probably going to be over UDP