This is a hypethetical question that I'm interested in knowing for sure...

Lets say I have three computers, and a Router. I'd like to moniter the network traffic on two of the computers, so I want to set one of the computers up directly to the internet, and then have that computer route over to the router, then connect the other two computers to the Router. Will I be able to tell which of the other two computers, which is connected to the router, is sending and recving data?

This is a small scale question, but I'm looking up to do it in case of larger scales come so just connecting both of the other computers to the machine I have between the router and the internet line wouldn't work.

The reason I ask is I'm not sure if it'll just all send me the Routers IP address, or if the computers will have their own IP address in the information sent to the computer setup before the router.

Thanks for the help in advance...