[Ulf Lamping <ulf.lamping@xxxxxx>]

Bob Langford wrote:
> Hello, - New list subscriber here.  I would like to capture traffic 
> from three PCs at my home.  They are behind a Linksys BEFSX41 router 
> which then connects to a Westel 6100 DSL modem.   If I placed a 4th 
> PC, running Ethereal, in the path between the Linksys router and the 
> DSL modem would I expect to get a good decode.  The protocol at that 
> point is PPPoE.  I have a three-way RJ48 jack I could use for this.   
> I'd lift the transmit pair from one end of the cat-5 cable going to 
> this 4th PC so there wouldn't be any signal mixing into the router 
> output from the PC.  
>  
> Would this work ? -
I don't think so, you'll need four RJ48 sockets.

What you're trying to do is to build a so called network tap.

But you'll usually need both directions of the traffic between the DSL 
modem and router.

See: "Capture using a network tap" at 
http://wiki.ethereal.com/CaptureSetup/Ethernet for more information.

Regards, ULFL