What is Deep Packet Inspection (DPI)?

Deep Packet Inspection, or DPI, is a technology that allows one to examine the data part of network packets, search for protocol non-compliance, viruses, spam, intrusions, and other statistical information, and decide whether the packet should be passed or dropped or routed to a different destination for further processing.

DPI is both a hardware and a software solution. A DPI device monitors the payload of each packet passing through it and detects protocols, applications, inappropriate URLs, intrusion attempts, and even malware present in the data packet. It is often used to enhance network security. And, Internet Service Providers often use it to decide on data usage, data limits, bandwidth, compliance with regulations, prioritization of traffic, load balancing, or collection of statistical data from its subscribers.

Let’s first understand how DPI works and how DPI technology has evolved.

OSI Model and Flow of Data

To understand how DPI works and how this technology has evolved, we must understand how a data packet flows through the OSI protocol stack.

The OSI Model

As per the OSI model, the communication system between the sender and receiver of a network packet is …


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Amrita Mitra


Ms. Amrita Mitra is an author, who has authored the books “Cryptography And Public Key Infrastructure“, “Web Application Vulnerabilities And Prevention“, “A Guide To Cyber Security” and “Phishing: Detection, Analysis And Prevention“. She is also the founder of Asigosec Technologies, the company that owns The Security Buddy.


  1. johnjonathan

    Very informative blog. This blog nicely explain all basics information on deep packet inspection. Deep packet inspection the practice of sniffing web connections to reveal sensitive user data and fend off cyber attacks.

    • tsb-author

      Thanks. It was glad to know that you liked the article.

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