[X-Unix] How to monitor inbound/outbound network traffic?

[Rad Craig]

Right now, I'm watching the light (xfer) on my network card and it's  
lit up almost solid, like I was downloading/uploading something,  
something (data) is going in or out.  I want to know what it is?   
Which application is sending it and what its sending.  I don't have  
anything running right now that should be constantly transferring  
data like this.  Its as if someone is sucking data off of my  
computer.  Is there a program/app/utility/script that will allow me  
to find out what is going on?


Rad...