For the sides that need to listen to an incoming connection (your server, typically), you'll need a direct port open, which might just be passed through via a N

For the sides that need to listen to an incoming connection (your server, typically), you'll need a direct port open, which might just be passed through via a NAT. For clients, it works like all other UDP applications, it just reaches out to the remote address and the NAT keeps a temporary mapping of the source and destination ports and addresses.