Currently I am developing an online game using sockets. I would like to know some way to debug whatever it send or receive.
I remember when I played ragnarok, there was a program that detect the sockets that you receive and send, and you could edit them and send again.
I would like to find a program like this, for debugging purporses only.
Wireshark is a great tool for viewing packets and you can even write your own dissectors for custom packet types.
If you need to somehow modify the packets I would probably try making a small app that runs in the middle and just forwards along any packets it receives. You could then debug in that app, or modify the packets however you want.
Wireshark should work well for reading the network.
You'll need another tool to write arbitrary data to the network. Netcat is perhaps the most awesome such tool available, but it's a little rough for those new to networking. I also found a few GUI-based alternatives dedicated to packet building from Engage Security, SoftPerfect Research and Colasoft.
I found a very useful tool called "WPE Pro", it allows me to edit and send sockets.