Ethereal-users: [Ethereal-users] Capturing IM

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From: "mkbuckley" <mkbuckley2@xxxxxxxxxxxx>
Date: Sat, 8 Jan 2005 14:12:20 -0500
I have a wireless network am trying to sniff.  I'm using a linksys 802.11g on my laptop talking to a  belkin wireless router connected to a cable modem.
 
I have 4 machines in the house. Only one is directly connected to the router.  Three others are all wireless.  PC1 is mine and is running ethereal.  When I capture packets I am able to see all traffic on the network including TCP, MSNMS, UDP, etc...
 
PC2 is a wireless laptop being used to connect to a corporate VPN.  This traffic appears as ESP or encapsulated security payload traffic, using IPSEC.  Am I correct in assuming there is no way to decrypt this traffic?  HTTP traffic appears normal.
My main question is this:  While I see a keepalive using the MSNMS protocol to port 1863, I see no conversation traffic, maybe because it is not taking place during the times I have monitored.  I assume this traffic should appear as normal also, or...and this is my question...is it too going through the VPN and being encrypted?
 
This might be a stupid question, but I am learning.  My objective is to capture and log all IM messages from any machine on the network using my PC.  I know there are programs I can load on the PC's to track all traffic, but I want to be able to do this from the network without loading any software on the machines. Any suggestions? Thanks in advance for your time and effort.  Great product, great site.