Migrating from Commercial DPI Library to nDPI

This document is a technical report detailing the journey of migrating from a commercial Deep Packet Inspection (DPI) library to nDPI. The author, Ivan Nardi, outlines the history of DPI development, starting from 2005 with the creation of an in-house DPI library, transitioning to commercial solutions, and eventually discovering nDPI in 2019. The report discusses challenges faced during this migration, including issues with QUIC support and licensing changes from the vendor of the commercial DPI engine. It compares various DPI engines and highlights the difficulties in making uniform comparisons due to varying protocols and classification capabilities. The report also presents the advantages of nDPI, such as maintainable code and a permissible license, while noting its limitations, including a lack of configuration options and slow development cycles. The author concludes with a reflection on the cost-effectiveness of nDPI compared to commercial alternatives, expressing confidence in the decision to migrate.