intercept data received and sent from my computer?

Question

I want to test a new protocol of communication, and for this i need to intercept every single package entering and leaving the network layer of the OSI model. any idea how to intercept those packages and perform the tasks i want to perform on them before letting them go.

Answer 1

http://www.charlesproxy.com/ is a great tool for intercepting, inspecting, modifying, and resending network requests. Its main mode is for http however it has an option to catch and forward any port and a socks proxy option. It understands quite a few payload formats natively and is very useful with minimum effort.

Answer 2

Wireshark is a useful program for letting you sniff network traffic (i.e. passively observe). And on *nix systems, raw sockets give you the ability to bypass most of the network stack and craft custom packets.

Answer 3

Use "Microsoft Network Monitor" if you want to check those Microsoft protocols. Well, though it's much slower than Wireshark.