[PLUG] Sniffing networking traffic

[Larry Brigman]

On Wed, 27 Oct 2004 06:10:03 +0000, Vincent Yau <v_yau3 at hotmail.com> wrote:
> 
> Hi:
> 
> I have one linux box and a VOIP adaptor.  They are connected to
> the same hub, then to a cable modem router and then
> to my cable modem.
> 
> I want the linux box to be able to capture network traffic
> that is directed to the VOIP adator.  I have turned on eth0
> to promiscuous mode.  I tried running both
> tcpdump and ethereal.  Neither detected anything
> beyond what is meant for the Linux box.
> 
> It is my understanding that by putting the linux on a hub, and turning
> its eth0 to promiscuous, I should be able to detect
> all traffic going through on the same hub.
> Am I missing a step?
> 

Double check that the hub is not a switch.  A lot of new gear these days are
actually ethernet switches.  And if that is the case you won't see any
traffic.