Verify Inbound Connections

Is it possible to (using something like Wireshark) verify that a game console actually is accepting inbound connections? I set up all the port forwarding rules on my router for my PS3 and it gives me a NAT Level of 2, but I still think something is wrong. I figure that finding at least one example of my PS3 accepting an inbound connection would indicate that my forwarding is working and an evening or two with no inbound connection would indicate a problem.