Pandora Network Traffic Analyzer (Pandora NTA) is a network traffic analysis tool designed for environments where you don’t want, or can’t, use Netflow to do a network analysis.
As a base for Pandora NTA/NTOP we use a fork of the NTOP project (of the version licensed as GPL2), besides the own code of the Pandora FMS project. It is in charge of collecting the data and sending them in XML format to Pandora FMS server. All that code is available in our public repository for anyone who wants it, because it is a 100% opensource functionality.
Check how it works in Pandora FMS Wiki