Trisul

Trisul is a robust tool that meters bandwidth usage, monitors flows, and stores raw packets for future analysis. All of its traffic data is stored in a SQLite3 database, which ensures that you'll have access to all the essential information you need.

Furthermore, this software suite communicates with the outside world using two methods: the Trisul Remote Protocol (TRP) and the Web Trisul, which is a Ruby-on-rails application. This feature helps you monitor your network's traffic effortlessly and reduce downtime.

What sets Trisul apart from other monitoring tools is its drilldown capabilities. With it, you can see top hosts using ICMP, for instance, from a specific time. The software's drilldown capability helps you analyze and understand your network's traffic.

There are numerous applications for Trisul's probing feature, including being a network analyzer, a source of statistical and flow data, a standalone web-based traffic monitor, network security monitoring, and forensics.

Overall, Trisul is an ideal software suite for all your network monitoring needs. It's created by Unleash Networks and is dual-licensed under the GPLv3.