What is Deep Packet Inspection

What is Deep Packet Inspection? Your Security Protocol 

7 Mins Read

PUREVPNPrivacy & SecurityWhat is Deep Packet Inspection? Your Security Protocol 

The number of cyberattacks worldwide increased by 125% in 2021 compared to 2020. These attacks are still rising and pose a significant threat to every company and every individual

From July 2021 to June 2022, cyber attacks in Australia increased by 81%. Network traffic grew by just 38% over the same period, indicating that cybercrime is still a significant issue in the country. Attacks on financial websites have increased by more than 200% in 2022. 

These statistics suggest that network traffic has increased significantly, and we must take action before it becomes a severe threat. 

In this article, we have discussed a technique you can use to manage network traffic called deep packet inspection.

What is Deep Packet Inspection

What is Deep Packet Inspection (DPI)?

DPI is a sophisticated technique for inspecting and managing network traffic. It filters packets by their payload, comprising specific data or code. Conventional packet filtering only examines the packet headers and cannot detect this form of packet filtering.

Deep packet inspection is usually part of a firewall defense. It is performed at the application level of the Open Systems Interconnection (OSI) reference model.

How Does Deep Packet Inspection Work?

Deep packet inspection is a generic term used in many software security products. Using deep packet inspection, you can examine the contents of each packet passing through a checkpoint and make real-time decisions based on the rules set forth by the network manager, ISP, or enterprise. 

Traditional packet filtering restricts itself to inspecting the packet’s header, whereas Deep Packet Inspection (DPI) adds value by more than just examining the title. 

It also takes packets containing specific data or code payloads and determines whether and how they will be rerouted or blocked.

Unlike stateful packet inspection, which only examines the header data, such as the source and destination IP addresses and port numbers, DPI analyzes a broader range of data and metadata about a single packet.

DPI examines packets closely as they reach an inspection point, looking for protocol non-compliance, viruses, spam, and other abnormalities.

A packet must be secured by non-compliance to proceed through the inspection point.

Techniques Used in Deep Packet Inspection

Deep packet inspection utilizes three main techniques: 

Pattern Recognition 

A firewall with intrusion detection capability inspects each packet against a database of known network attacks. It recognizes specific patterns typical of malicious activity and then blocks traffic displaying them. 

This method is limited to known threats, but regular updates to the signature database are vital to its effectiveness.

Protocol Anomaly Detection 

The design of the protocol anomaly approach is quite different from that of pattern matching. It adopts a default deny approach. 

The firewall determines what is considered content based on protocol definitions and only lets authorized traffic pass. This approach offers protection against attacks known and unknown.

Intrusion Prevention System (IPS) 

In real-time intrusion prevention systems, proactive defense identifies and stops malicious packets from being sent based on the contents of the packet. If a packet is recognized as one that matches a defined security threat, the IPS denies it using defined rules. 


The cyber threat database must be updated often because establishing a baseline behavior model, enforcing stringent policies, and routinely analyzing alerts and events are all necessary to minimize false positives. 

Modern vs. Conventional Packet Filtering 

However, traditional forms of packet filtering considered only packet header information. This is like reading an address written on an envelope but knowing very little about the contents of the envelope. Part of the reason was the inherent limitations of the older technology.

In the past, firewalls lacked the performance to inspect large volumes of traffic in real time. DPI can also perform ever more advanced inspections, with checks not only of packet headers but of data as well. All of this is possible because of the advances in technology.

Furthermore, DPI can read the contents of a message and decide which specific application or service sent it. 

Moreover, filters can be configured to monitor network traffic for a particular Internet Protocol (e.g., 123.567.12. 134) or service (e.g., Facebook, Twitter, etc.). If a match is found, it can also redirect it to a different location. 

What Are The Uses of Deep Packet Inspection?

Let’s see the uses of deep packet inspection.

Identification of Malicious Traffic 

DPI is used for several reasons in network security and management. It is a robust tool for identifying and intercepting malicious traffic. 

DPI is often used by firewalls with intrusion detection features and standalone intrusion detection systems.

Network and Policy Management 

DPI is essential for network management and adjusting content policy, avoiding data loss, and throttling network traffic flow. 

For example, delay-sensitive, high-priority messages can be fast-tracked. 

Network Performance 

DPI can also moderate data transfers and improve network performance overall.

Protection from Viruses and Malware 

DPI is widely applicable in many different scenarios. It serves as an intrusion detection system and a combination of detection and prevention, identifying attacks not caught by standard security systems. 

Without DPI, corporations cannot prevent the entry of such viral threats as worms, spyware, and other viruses from the user’s laptop.

Network managers use DPI to deal with streamlining traffic flow, prioritizing important data, and dealing with problems such as peer-to-peer downloads.

Malefic Use of DPI

While there are also beneficial applications, concerns are raised over DPI’s risk of misuse. It can be used for good, which includes detecting security threats, and for evil, such as eavesdropping and state-sponsored censorship. 

DPI can, therefore, be used to determine the sender or recipient of individual packets, which worries proponents of net neutrality and privacy.

Furthermore, DPI can be used for different purposes, such as personalizing services to suit the needs of each subscriber, copyright protection of online content, targeted advertisements, lawful interception, or implementation of policies. 

However, the dual nature of DPI must be addressed because it can be employed for less honorable ends, like censorship and eavesdropping, as has already been shown in Chinese government operations.

Benefits of Deep Packet Inspection (DPI)

DPI provides many benefits to corporate networks and organizational network performance.

Robust Protection For Businesses 

Going beyond packet headers, DPI has become one of the most critical security tools. It can uncover hidden threats and defeat attacks that have already been detected within the contents of the communication. 

Using this capacity, businesses can stop data leaks, identify usage patterns rapidly, identify and eliminate malware, and combat other threats affecting the network and its users.

Identification of High and Low-Priority Packets

In addition to security, DPI offers flexible options for handling network traffic flows. Using rule programming, DPI enables the detection of specific data, the identification of high and low-priority packets, and the prioritization of critical packets at any point in the data stream. 

This channelizing allows higher-priority or mission-critical packets to go through the network faster than ordinary browsing packets or low-priority messages.

Handling of Packets in Real-Time 

Organizations can determine whether unauthorized use has taken place by referring to the defined rules and policies that determine which applications are approved. 

To prevent data leaks and to choose the destination of data packets, DPI extends its range to include outbound traffic detection. 

All packet information, from headers to contents, must comply with predetermined rules and be handled in real-time. This sorting, filtering, and prioritization is done automatically and without slowing the network.

In addition, DPI allows organizations to act on traffic profiles, for example, generating alerts for dropped or lost packets or throttling the bandwidth for certain types of traffic.

Drawbacks of Deep Packet Inspection (DPI)

Although Deep Packet Inspection (DPI) is an effective tool for network security, several issues highlight its shortcomings.

Guard and Threat 

DPI works well against attacks such as denial of service, buffer overflow, and certain malware but can also be used to mount such attacks.

Increased Security Difficulties 

Implementing DPI technology will, in general, create additional difficulties. Existing firewall and security software setups and configurations must be constantly upgraded and polished to retain full functionality. You have to handle these complexities for solid security effectively. 

Sluggish Network

One of the significant drawbacks of DPI is that giving resources to the firewall to handle the processing load can hamper network speed. This slowdown can affect network performance in general.

Privacy Concerns 

Besides this, there are still worries about privacy, mainly as more people use HTTPS certificates and VPNs with privacy tunneling. A few firewalls have implemented HTTPS inspection in response to these worries. 

This process involves decrypting HTTPS-encrypted traffic to determine whether or not the content is acceptable. 

Nonetheless, DPI remains a valuable technique offering capabilities like enterprise security, network analysis, performance management, and forensics analysis.

Elevate Your Security System With a VPN

Deep packet inspection is undoubtedly a powerful method for managing networks, but not foolproof. Minor negligence can cause you or your company significant damages. Therefore, you must introduce an extra layer of security in your network with a VPN.

We highly recommend you use PureVPN. It has 6500 servers available which you can use to set your location and trick the hackers. It can mask your actual IP address by assigning you a new address, which will be unique for your network. It is effortless to use. All you have to do is: 

  1. Download PureVPN.
  2. Purchase a subscription.
  3. Connect to a server.
  4. And that’s it. 

Be Careful- Hackers on Loose

Today, business is increasingly digital and networked, and hackers and cyber attackers are on the loose. Organizations are using deep packet inspection as part of the network security strategy. 

It is the firewall that protects their network and their users. However, more is needed. Use PureVPN to increase your network security and protect yourself from the potential threats. 


Marrium Akhtar


January 2, 2024


7 months ago

Marrium is a dedicated digital Marketer and an SEO enthusiast who is skilled in cracking SEO codes. Other than work, she loves to stream, eat, and repeat.

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