Wireshark · Ethereal-users: Re: [Ethereal-users] configuration

[Guy Harris <gharris@xxxxxxxxx>]

james wrote:

> I have attached picture.

Much better.  Thanks.

> I have set up my network to monitor the messages of the IP phone
> using a PC with Ethereal as in attached diagram.
>  
> Since Adsl modem is in bridge mode is it possible to monitor the messages.
> If can how?
>  
> To my understanding only one equipment can be connected  in bridge mode. 

If by "bridge mode" you mean the ADSL modem is sending bridged Ethernet 
over ARP (that's how my ADSL modem is configured), then you could, in 
theory, have multiple devices connected to the hub sending traffic over 
the bridged Ethernet - for example, my ISP allows me to have up to 4 
static IP addresses, so I could connect up to 4 devices with different 
IP addresses.  I don't know what your ISP allows.

If your ISP allows only one IP address, so that only one device can 
access the Internet through the ADSL modem, you could disable host name 
resolution in Ethereal, so that it doesn't have to use the Internet to 
analyze traffic.  As long as the hub is a real hub, not a "switched hub" 
(which is really just a cheap switch) and, if it's a dual-speed 
(10Mb/100Mb) hub, as long as Ethereal and the IP phone are running at 
the same speed, you should be able to capture all the traffic the IP 
phone is sending and receiving, as long as the PC's network card and the 
OS's driver for the network card support promiscuous mode.