How to observe data leaving my machine before it hits the router

[Sumotku]

Put another way, how do I spy on myself? I'd like to know what's being transmitted under my nose, and actually have the data be in a decipherable format where possible. I figure I can filter with my firewall but that's a rather uninformed decision. Is it doable?

 

[JackMDS]

Firewalls that have flexible Rule system can help in filtering application and specific type of communication.

I do not think that you would find a general applications that shows across the board what is about to go out and ask your permission to send it.

Otherwise, may be this can Help, http://www.httpwatch.com/

 

[Tarrant64]

Wouldn't utilities such as Ethereal give you the information you need?

You should be able to filter it out by HTTP or whatever protocol you have in question.

 

[Crusty]

Yeah, Wireshark should be able to tell you everything you need.

 

[Sumotku]

Thanks for the leads, looking into Ethereal WireShark and Httpwatch now. Looks promising.