A good network monitor to catch an attacker

someone is sending a gameserver im running packets it cant understand and crashes it. i need a good network monitor to see who was the last IP sending packets to the games port. any suggestions?
Answer #1
Wireshark is one great utility. But to fully understand its functions, u can download the Wireshark University course available here. Course 1 covers basic functions. Wireshark software is one kicka$$ product to monitor problems and increase efficiency.