On May 1, 2004, at 10:19 AM, herzog@xxxxxxxx wrote:
On Tue, 27 Apr 2004, james wrote:
I have a 1 ip phone connected to a 4 port ethernet adsl router to
make
voip calls. My pc(loaded ethereal analyser) is connected to another
port on
the same 4 port ethernet adsl router.
Is this configuration right to capture the protocol exchanged
between my ip
phone and voip provider using my pc.
No. More than likely, those 4 ports on the broadband router are
switched,
so your PC will not be able to see traffic which is not originated
from nor
destined for your PC.
What you will need to do it either buy a cheap hub and plug the PC,
the IP
phone, and the router into it...or, buy an ethernet tap to put in-line
between the IP phone and the router (would also require a second NIC in
the PC if you which to maintain internet access from the PC while
sniffing
traffic)...
--
Larry Herzog Jr. "Do nothing out of selfish ambition or vain
VROC #11489 conceit, but in humility consider others
herzog@xxxxxxxx better than yourselves." - Philippians 2:3
Before you spend any money, try - first - to set the port speed and
half-duplex for the analyzer's NIC to be the same as the one negotiated
between the IP phone (see if you can make it half-duplex, also) and the
ADSL router/switch. I have seen one too many times these router with
"switched" ports behaving like hubs, when the connected devices are on
the same speed and duplex, and working in switched mode only when one
is 10Mbps, and one 100Mbps, for example ...
... just a suggestion - cheap to try ;)
Stef
