How to track packets in Yahoo messenger!

I am trying to understand the header/protocol format of yahoo messenger.

I see limited documentation for yahoo messenger when I googled. So I wondered if there is any tool to help me out to trace th开发者_开发技巧e packets? It would be nice.

Or is there any good documentation on yahoo messenger protocol which would also help me? Refer me to any tools or documents that can help me.

Have a look at Wireshark.

There are open source projects that support the Yahoo! messenger protocol, you could probably learn a lot from their source code, as the reverse-engineering has already been done for you. libpurple (used by Pidgin and a bunch of others) supports it, for instance.