What is Deep Packet Inspection? (Secrets…)

What is Deep Packet Inspection? (Secrets...)

What is Deep Packet Inspection? (Secrets…)

Deep Packet Inspection is a method of filtering packets to monitor and control internet traffic. This is done by inspecting the packet data, hence the name “deep packet inspection.” It has many benefits for businesses, but it can also be used to track down people doing illegal things online. We will dive into what deep packet inspection is and how you can use it with your business.

What Is Deep Packet Inspection?

Deep Packet Inspection (DPI) is a form of data inspection that goes beyond just simple packet filtering. DPI can be used to decrypt encrypted connections and also helps in identifying applications. This type of data inspection is becoming increasingly common, even in consumer-grade products.

Deep Packet Inspection (DPI) consists of inspecting and processing the contents of network packets that are passing through a router or other networking device at high speed. This form of traffic monitoring has several advantages over application layer filtering: it can be used to decrypt encrypted protocols such as TLS/SSL; it allows applications to be identified regardless of encryption; and also provides finer granularity than simple port blocking by allowing certain operations on an entire class of applications.

How Does It Work?

DPI works by inspecting Layer-III (Host to Network) and some Layer-II (Network Access/Link) headers.  The ability to inspect the contents depends on how deep in the network stack that packet inspection is implemented and what data it can access from higher layers such as protocol metadata, port numbers, etc. In addition to this, DPI equipment usually records a variety of statistical information about traffic passing through them, allowing for analysis at later stages.

This enables applications or protocols to be identified regardless of encryption used – very useful when identifying file-sharing or PTP application use over encrypted connections like SSL/TLS where only transport layer ports are visible unencrypted!   When using link-level encryption such as SSL/TLS, DPI can only monitor the traffic between client and server. It cannot see internal network structure or identify hosts without terminating the connection first. 

However, for link-layer encryption to be effective, it has to be used end-to-end (i.e., by both ends of a communication channel) – monitoring individual links is “very easy” using low-level packet inspection techniques such as those employed in Deep Packet Inspection systems where entire packets are reassembled before filtering/analysis occurs; if one end doesn’t support link-layer encryption then this type of inspection becomes trivial because all data sent on that particular medium is decrypted!

What Kind Of Information Can You Get From Deep Packet Inspection?

Using Deep Packet Inspection (DPI), getting a wide range of information about an individual connection is possible. This can include:

Network Addresses Of Both Client And Server 

These can be used for further more detailed analysis, including geolocation using GeoIP services (e.g., MaxMind); or network mapping using SNMP tools that allow reverse DNS lookups on IP’s to identify hosts providing certain kinds of content, e.g., PTP video streaming servers.

Protocol Metadata 

Protocol Metadata such as port numbers and protocol header data allowing traffic analysis and classification by type/application; this includes features like file type identification for specific PTP applications like BitTorrent clients or video streaming apps that send “well known” headers in their initial handshake packets making them easy to identify regardless of encryption being used.

Other than identifying what kind of communication has taken place between two machines, other valuable things can determine with DPI systems such as:

How Much Bandwidth An Individual Or Group Of Users Is Using 

This can be used by ISP’s to implement fair use policies for all subscribers.  This also helps in identifying heavy downloaders, BitTorrent usage, etc.

Traffic Anomalies 

Traffic anomalies such as unusually high upload/download speeds helpful in dealing with illegal PTP applications like uTorrent that allow torrent seeding directly from one user to another without going through a central server location (see the “Swarm Amplification” attack). This allows ISPs and copyright owners to deal with traffic before too many people are affected quickly. 

DPI systems typically implement some form of traffic classification, allowing them to identify standard PTP protocols making it easy for ISPs to selectively throttle these types of applications without impacting the performance of other services.

Traffic Content 

Even if encrypted! This allows for easy identification of PTP protocols and file-sharing traffic over SSL/TLS connections where only a single port is visible unencrypted (e.g., BitTorrent or IPP). This can have legal implications as not all countries apply the same restrictions to these types of activities, which also makes it easier for ISPs, copyright owners, etc…to detect illegal activity such as uTorrent seeding without having to monitor each connection at the packet level (which would be very resource-intensive with high-speed links like those available on modern broadband cable networks). 

It’s worth noting that DPI systems are usually implemented in hardware making their use scalable; this means that you can easily monitor traffic at very high speeds (100Gbps+) without impacting the performance of other services.

The application used to create the connection, e.g., Skype, Email client, etc.

The duration of the connection, e.g., how long it took to download/upload a particular file(s).

Why Do People Use DPI?

DPI is a powerful tool for network managers to use to manage their networks more effectively. In the days before DPI, administrators would have had no choice but to allow all traffic that was allowed onto an internal network – even if it posed a security risk of some kind.

With DPI appliances, this problem has been solved by allowing admins control over what type of data packets they want on their networks and how they are handled once entered via firewall rulesets which can be configured based upon user-defined parameters such as destination IP address or port number. 

This means that while ISPs may monitor customers’ activity within secured connections at Layer seven, corporate organizations might also choose to implement similar technology when users access company resources through VPNs or remote desktop connections – as DPI appliances can be configured to monitor such activities and enforce acceptable use policies, even when on private networks.

The Dangers of Deep Packet Inspection

Most people understand by now just how dangerous it is for ISPs and governments alike to have access at Layer seven into what their users do on public networks – as there’s always a chance that such power could be abused to stifle free speech or censor any kind of online activity deemed unacceptable by those who lead them. 

People should also remember, though, that every time we create an Internet connection with someone else – whether through email, our social media accounts, or even passing information across secure SSH connections, we’re essentially opening ourselves up to the possibility of surveillance. There may not be many individuals who can do this, but corporations who choose to implement these systems must be held accountable for how they use them.

The risks of having a third party monitor all your online activity

Are not restricted to just the threat of data loss or exposure, though. Just as with government surveillance, where there is power – corruption will follow. On corporate networks, this could mean that unauthorized users can access sensitive information by abusing DPI systems installed for security purposes but end up being used as a sort of ‘backdoor’ instead (perhaps due to financial reasons).

DPI technology can also pose some other problems too; one thing worth mentioning here is that ISPs can use their knowledge about your online behavior to target advertising based upon your browsing habits and interests, effectively turning them into an ISP/Middle man who has control over what you do on the Internet. 

Not only would such activity be considered unethical by most, but it could also lead to legal action being taken against ISPs who are caught doing this – as the EU has already declared web browsing history to be personal property.

Ways To Protect Yourself From Deep Packet Inspection

If you’re concerned about your online privacy – then there are a few things you can do to help protect yourself from the prying eyes of ISPs and governments alike. 

One way would be to use a VPN service, which essentially ‘tunnels’ all of your Internet traffic through an encrypted connection that only you have access to, so no one else can track what sites or services you visit while using public networks. 

Suppose this sounds like something worth doing, though. In that case, it should also be noted that many countries now require their citizens/residents to register with them when purchasing VPNs for such software packages to work within their borders legally. 

This means that if someone were ever caught trying to connect via a secure encryption channel while in a country that does not allow such packages to be used (or if they were found to use one which was registered in an illegal manner), it wouldn’t take long at all for the authorities to figure out who had been using it.

Tor is probably your best bet when trying to browse anonymously online, as this free software protects you by bouncing communications around a distributed network of relays run by volunteers from across the world – making it difficult for anyone to trace where exactly data packets have come from or gone too. Despite being developed with good intentions, Tor has unfortunately become somewhat infamous among some governments and corporations after being branded ‘The Onion Router.’ 

This term refers back to its ability to obfuscate Internet traffic through layers of encryption. At the same time, routers work like layers of onion after being peeled back one by one to reveal the core of your sensitive data.

Pros and Cons of Using Deep Packet Inspection System

There are many pros and cons associated with using deep packet inspection systems,

it can be used for legitimate purposes such as monitoring bandwidth usage to ensure that users aren’t hogging more than their fair share of bandwidth. On the con side, there’s always the risk that these appliances will be used for other purposes such as spying on users and collecting data that could potentially end up in the wrong hands.
This is important because ISPs want all customers to use equal resources, so no one person or group slows down speeds for everyone else on the network. If DPI systems are misused, it puts your identity at risk by allowing others to access personal information, including who you’re communicating with online – not to mention what types of files you might have stored on your computer without encryption!

However, suppose someone does use too much data. In that case, companies can either alert them directly through email or automatically cut off service until they upgrade to a larger plan – which might not cost any extra money! DPI allows you to monitor this exact thing, so your connection remains fast at all times.

The Future of Deep Packet Inspection

In the future, there’s a possibility that it might be used to censor content online or even sell ads against user data – which would essentially mean corporations are profiting from your private information without compensation. While many governments are trying to put laws in place that prevent this type of activity, there’s no guarantee they’ll be effective at preventing it. 

This is why the onus has been placed more heavily on corporations themselves and end-users who can help by demanding changes through their wallets – which means not supporting companies who engage in unethical data collection practices.


A deep packet inspection is a powerful tool, but it’s also hazardous if companies abuse their power by spying on their users and collecting data without consent.  It’s essential to be aware of the potential risks, consequences, and benefits associated with using DPI systems before you decide whether or not it’s right for your business.

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