When you are tasked with monitoring network traffic on the local network, you can consider many different options to do it, depending on the scale/traffic of the local network, monitoring platforms/interface, types of backend database, etc. ntopng is an open-source (GPLv3) network traffic monitor which provides a web interface for real-time network traffic monitoring. In this tutorial, I will describe how to set up a web-based network traffic monitoring system on Linux by using ntopng.