Understanding Deep Packet Inspection

Nadin Bhatt
Nadin Bhatt | Writer
Last updated: July 26, 2021
analysis of files transfered from one computer to another
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Every bit of digital information, including emails sent, Skype calls made, and websites loaded, is conveyed across the Internet in a configured piece of arranged data referred as a packet. This packet contains arranged metadata that ensures data is properly routed to its destination. The analysis of these packets is referred to as Deep Packet Inspection (DPI), and the practice is used on a daily basis by companies, internet service providers (ISPs), and media organizations.

So, what is Deep Packet Inspection (DPI)?A network packet is a configured and subtle unit of data. Deep packet inspection is a means of analysis that analyzes network data to extricate useful metadata. Deep packet inspection explains network trends, assists ISPs in optimizing bandwidth and can also uncover user behavior. Since deep packet inspection essentially involves revealing sensitive data, IT departments, ISPs, and consumers are most affected by the practice. Deep packet inspection has been a valuable IT tool for almost two decades. As the internet advances to also comprise mobile as well as IoT devices, DPI is becoming more and more prevalent.

The following article will ask what is DPI and how does it affect users.

What Is Deep Packet Inspection (DPI)?

To further understand what is DPI, we need to understand that Internet traffic is comprised of small data bundles referred to as packets. Packets contain digital information in a metadata cocoon that detects traffic source, content, destination, and other valuable pieces of information. The analysis of digital traffic is similar to the analysis of car traffic: Patterns can uncover valuable insights. The study of metadata such as headers that utilize deep packet inspection allows network specialists to learn how to enhance servers to minimize overhead, identify and prevent hackers, combat malware, and collect personal information regarding user behavior.

Even though Deep Packet Inspection has several uses, the practice is closely related to enterprise network security. Analyzing data that enters and leaves a network is useful to prevent and detect intrusions. The detection and obstruction of the IP of malicious traffic is especially effective at preventing buffer overflow and DDoS attacks.

DPI is also utilized by internet service providers. If packets are related to mail, ISPs act as the postal service, accessing unencrypted web traffic and packet metadata such as headers. This provides internet service providers with important information, and companies utilize user data in numerous ways. Most internet service providers in the US are permitted to hand user data over to law enforcement agencies. Also, many internet service providers use consumer data to focus advertising, examine file sharing habits, and tier speeds and access service.

Why DPI Matters?

Although packet inspection is a somewhat dated technique given the endless array of connected devices, DPI is more relevant today than in the past. DPI is relevant for three primary reasons:

Scale of connectivity

Nowadays, the internet, especially mobile internet, is more important to more people than ever before. Every company and organization depends on network inspection technology to enhance traffic and minimize cyber attacks. Though Deep Packet Inspection is not their only line of defense, for many institutions, scanning and analyzing packets is the primary line of defense.

Growing IoT market

Just like the mobile market, the Internet of Things (IoT) means millions of added devices will connect to the Internet in the next few years. Modern IoT devices don’t have standardized firmware and security standards that can protect the devices from being dragged into a zombie botnet. DPI will protect networks and ISPs from IoT DDoS attacks as well as assist security analysts in learning more about dangerous IoT security flaws.

Privacy concerns are mainstream

DPI assists media companies in learning about customers more than ever before. Every page loaded and every piece of communication sent is filtered and transmitted through an ISP. Internet service providers are now vertically combining with media companies and leveraging data to target consumers with advertising and aid law enforcement agencies with intelligence collection.

Who DPI Affects?

Aside from enterprise and SMB companies, DPI is primarily used by:

Media companies

Media companies are known for executing mergers, therefore, when ISPs buy media companies, they combine broadcast data with digital data to define everything from consumer internet service prices to television and web programming by relying on Deep Packet Inspection.

Law enforcement agencies

It is legal and often required that ISPs collect and share DPI-gathered data for crimes that involve intellectual property violations and drug and human trafficking.


The majority of consumers know that, whether they like it or not, their personal data is for sale. The majority of consumers, however, are unaware that their ISP is undoubtedly scrutinizing, anonymizing, and reselling personal internet browsing data to advertising companies.

When DPI Occurs?

Deep packet inspection, also referred to as full packet inspection or data packet inspection, harks back to the ARPAnet. The ARPAnet predated the internet we know today and was the first computer network to utilize the TCP/IP data transfer protocol. Managing proto-packets allowed engineers to learn how to employ header and metadata information to alleviate security obstacles related to UNIX.

ARPAnet virtually disappeared in 1990, but as the modern internet became commonplace so did TCP/IP challenges. A model referred to as Open Systems Interconnect (OSI) was designed by network engineers in the 1980s to standardize metadata set by the mid-1990s. By validating packet metadata tiers, OSI enabled an array of statistical analysis. As an example, secondary headers, referred to as stateful or shallow data, enable information to be correctly routed but cut bandwidth.

Tiered packet metadata also meant ISPs could more easily differentiate between types of data. With the boom of Web 2.0 and mobile at the beginning of the 21st century, ISPs understood deep packets could stimulate new business models. Net neutrality has been widely discussed for nearly two decades, and deep packet inspection technology has converted pipe owners into data owners.

How to Conduct DPI?

DPI is a proven technique, but the IT industry is continually changing. The biggest trend in DPI is dedicated hardware. Cisco and other networking manufacturers have produced routers that are specialized in packet sniffing and network awareness.

DPI is a central component of IT, and EXPERT network managers can provide information about how companies gather data. Those working in IT can consult their standards and practices or legal department for usage guidance. Although it is often legal to collect customer data, the industry is deeply regulated. DPI can be a powerful tool, but it is important to remember to follow the law, not violate company policy, or engage in unethical behavior.

Final thoughts

Market research analysts have projected that the global mobile deep packet inspection (DPI) market will develop greatly in the next seven years and will post a CAGR (the Compound Annual Growth Rate) of almost +25% by 2025. Mobile deep packet inspection scrutinizes, monitors and assesses data packets in a mobile application or device. It is a mobile security and monitoring practice that allows packets to be evaluated for security issues at the application level.

Some of the central drivers for market growth are increased IP traffic as a result of the adoption of high-speed broadband internationally, increased penetration of mobile devices and heightened competition among network service providers.

On the other hand, privacy and network neutrality concerns, lack of deep packet inspection (DPI) understanding and accessibility of open source DPI are some of the primary impediments to market growth.

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  1. 987amelia

    I think DPI is still growing and while for many people out there, it may seem like a whole new thing, but as it grows, it will be something everyone gets accustomed to, just like Bitcoin, which is slowly gaining prominence

  2. Roy K.

    We are now living in an era that couldn’t have been imagined (by most of us at least) 30 years ago. We are constantly monitored by companies so they can show us ads about what we want and also by governments that are supposedly trying to stop crimes. We are living difficult times.

  3. Elisa Futsum

    Why DPI, is Firewall not enough?

  4. XFolium65

    I was reading an article on Deep Packet Inspection the other day that this form of filtering and transferring data packets from one computer to another is widely being used by cloud-generation firewalls these days. It also allows the inspection of network data and helps filter out malware and unwanted traffic.

    1. avatar
      Nadin Bhatt Author

      That’s true — that’s how China’s Great Firewall is allowed to be so strong. Technology is technology, whether for good or bad usage 🙂

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