What is Deep Packet Inspection? How it Works and Why It Is Important

Filip Cotfas, Channel Manager, CoSoSys

By Filip Cotfas, Channel Manager, CoSoSys 

Every piece of digital information, whether it’s emails, accessed websites, or messages sent via apps, are transmitted over the internet in small bundles of data known as packets. These packets contain not only the information itself but also a layer of metadata that identifies traffic source, destination, content, and other valuable details, that ensure that data is routed to the proper destination. The process of analyzing these packets, known as deep packet inspection (DPI), is used every day by enterprises and internet service providers (ISPs) to detect and prevent cyber attacks, combat malware, optimize servers to reduce overhead, and analyze user behavior.

DPI, also known as complete packet inspection and information extraction, is an advanced method of inspecting and managing network traffic and is considered an essential tool for advanced IT security. Going a step further than basic packet filtering that examines only packet headers and is usually applied through routers, DPI analyzes the actual data content of the packet along with the headers. It can search for non-compliance with protocols and filtering rules, spam, viruses, or malware and based on results, classify, reroute, or block packets.

DPI is rooted in network security due to its usefulness in preventing and detecting intrusions. Identifying and blocking the IP of malicious traffic, for example, is very effective against buffer overflow and DDoS attacks. DPI detects threats at the network layer before they reach end-users which can help prevent viruses and malware from spreading through the entire company network. Consequently, DPI is often included in firewalls, where, combined with additional security capabilities, it keeps company networks secure from a range of threats.

DPI can also be employed for network management. It can filter traffic and ease the network flow by assigning different levels of priority to messages and peer-to-peer downloads or detect prohibited uses of company applications.

But how does DPI relate to Data Loss Prevention (DLP)? By applying filtering rules related to confidential information, DPI can block the sending of sensitive data, prompting users to seek permission or clearance before an email is sent. As a standalone DLP tool, DPI is limited and can be a frustrating experience for both employees and managers, but when it is used as part of a DLP solution, it can bring a number of advantages.

By using DLP solutions with DPI, companies can identify the exact destination a file is transferred to, making it easier for them to block or white list specific websites. In this way, organizations can allow the use of browsers such as Chrome, Firefox, etc., but ensure that they know where data transfer attempts are being made on them. It helps companies make informed decisions about which websites need to be blocked and which are legitimate company-authorized transfer channels.

Organizations can also white list domains for email clients, meaning that the transfer of sensitive data can be blocked to all addresses except those of relevant departments such as Finance and Human Resources. Flexibility is essential to ensure that DLP policies do not hinder the work of employees that need access to sensitive data on a daily basis to perform their duties.

DPI is a great addition to DLP solutions, bringing with it a higher level of precision in the application of DLP policies. It actively reduces the impact of DLP on employee productivity, automatically eliminating undesired sensitive data transfer destinations while allowing for the use of legitimate channels.


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