May 26th, 2005, 04:37 PM
Sniffing VoIP Using Cain (Flash)
As stated on Wikipedia.org:
Voice over IP (also called VoIP, IP Telephony, and Internet telephony) is technology enabling routing of voice conversations over the Internet or any other IP network. The voice data flows over a general-purpose packet-switched network, instead of the traditional dedicated, circuit-switched voice transmission lines.
In this tutorial Iíll show how to use Cain to do a simple capture of half of a VoIP session. You can download Cain from:
http://www.oxid.it/cain.html Cainís VoIP sniffing function supports the following codecs: G711 uLaw, G771 aLaw, ADPCM, DVI4, LPC, GSM610, Microsoft GSM, L16, G729, Speex, iLB and my understanding is that it is under active development so expect more to come. For more information on VoIP support in Cain see:
The Flash animation tutorial is at:
June 15th, 2005, 10:16 PM
Added a Flash video to my site called ďMAC Bridging with Windows XP and
It should me useful with my Cain/VoIP tutorial, or with any sniffer you want to hook on the line.
December 7th, 2006, 07:20 PM
Thanks for the tutorial. I am able to capture both sides of the VoIP session, however the audio is very choppy. When calling in to the VoIP both sides are equally garbled. When calling out from VoIP the outgoing side is all static. I am using Vonage. Do you have any idea on how to fix this? Thanks!