54. Advanced Network Security: Deep Packet Inspection

Many of today’s security threats come from data breaches and cyber-attacks on computer networks, typically initiated from the outside or by disgruntled team members. In response, many multinational and small-medium enterprises are protecting their infrastructure with sophisticated methods like Deep Packet Inspection (DPI).

Understanding Deep Packet Inspection (DPI)

DPI refers to a technique used in packet filtering that examines the data part (and possibly the header) of a packet as it passes an inspection point, typically at a firewall. By taking a microscopic look at the packets, DPI identifies viruses, spam, intrusions, and other defined criteria to decide whether the packet is legitimate or needs to be rejected (Kumar & Dutta, 2017). It’s essentially the network equivalent of anti-virus software, but it operates at a much more advanced level.

Use cases for DPI

DPI, due to its advanced capabilities, has a wide range of uses. These include:

• Network Security: DPI forms part of an organisation’s cybersecurity infrastructure, allowing detection of malicious patterns or signatures within packet payloads.
• Policy Definition/Enforcement: DPI provides fine-grained control over network resources, allowing organisations to implement detailed, specific usage policies.
• Traffic Shaping: Also known as “packet shaping,” this is the control of computer network traffic to optimise or guarantee performance, reduce latency, and/or increase usable bandwidth by delaying packet flows considered less important.

How DPI Works

DPI works by closely inspecting packets that pass through a checkpoint, instead of merely examining basic data like the IP address or packet header. It categorises traffic on the network based on predefined rules and policies and can make real-time decisions whether to allow the packet to pass, reroute it, or even drop it entirely(Zhauniarovich, 2016).

The steps followed by DPI include:

1. Packet Decoding: The first step includes decoding the packet to understand its structure.
2. Detecting Protocol: Determining which application protocol the packet is using, such as HTTP, FTP etc.
3. Content Analysis: This step involves deep inspection of the packet’s payload.

While DPI does add processing overhead due to its meticulous scanning process, the trade-off is improved network security.

Privacy Concerns and DPI

While DPI allows for unmatched detail in firewall technology and traffic management, it also stirs a heated debate about user privacy. As DPI can read the content of packets, it also has the potential capability to read sensitive data. While most enterprise implementations of DPI will anonymize data where possible, the capacity for DPI technologies to overreach privacy regulations like GDPR and the UK’s Data Protection Act is a real concern, and organisations must use DPI responsibly.

Conclusion

Deep Packet Inspection is a vital tool for maintaining network security and managing traffic. While it does introduce additional overhead, and comes with serious privacy concerns that need to be managed, in the hands of a responsible organisation, DPI can be a significant line of defence against modern network attacks.

In the next session, we’ll discuss the various DPI tools available in the market and how to evaluate which solution is right for your organisation.

Further Reading

For those interested in learning more about DPI and its applications, the following resources are recommended:

1. Kumar, B., & Dutta, K., “A comparative study of deep packet inspection (DPI) tools and methods,” Procedia Computer Science, Vol. 113, 2017, Pages 329-336, ISSN 1877-0509.

2. Zhauniarovich, Y., “Efficient State Merging in Symbolic Execution,” ACM Digital Library, 2016.

3. DPI Insights. This is a frequently updated blog about the latest developments in DPI and network security. The information here is dense and technical, but it offers deep insight into the world of DPI similar to what you’d find in an industry publication. You can find it here.