Trisul is a network metering and forensics tool. You can install Trisul on any Linux box and have it look at network traffic in real time or via capture files. It meters the traffic (by host, by protocol, by subnet, etc) and stores the results in a SQL database.
Trisul also includes a Ruby on Rails application called Web Trisul that allows you to use a web browser to view data in the form of pretty charts.
