Network forensics
From Forensics Wiki
Network forensics is the process of capturing information that moves over a network and trying to make sense of it in some kind of forensics capacity. A network forensics appliance is a device that automates this process.
There are both open source and proprietary network forensics systems available.
Open Source Network Forensics
Snort
Proprietary Network Forensics
Sandstorm's NetIntercept
NIKSUN's NetDetector
