What Is Deep Packet Inspection and Why the Controversy?

By Art Reisman

Art Reisman CTO www.netequalizer.com

Editor’s note: Art Reisman is the CTO of APconnections. APconnections designs and manufactures the popular NetEqualizer bandwidth shaper. APconnections removed all Deep Packet Inspection technology from their NetEqualizer product over 2 years ago.

As the debate over Deep Packet Inspection continues, network administrators are often faced with a difficult decision: ensure network quality or protect user privacy. However, the legality of the practice is now being called into question, adding a new twist to the mix. Yet, for many Internet users, Deep Packet Inspection continues to be an ambiguous term in need of explanation. In the discussion that follows, Deep Packet Inspection will be explored in the context of the ongoing debate.

Exactly what is Deep Packet Inspection?

All traffic on the Internet travels around in what is called an IP packet. An IP packet is a string of characters moving from computer A to computer B. On the outside of this packet is the address where it is being sent. On the inside of the packet is the data that is being transmitted.

The string of characters on the inside of the packet can be conceptually thought of as the “payload,” much like the freight inside of a railroad car. These two elements, the address and the payload, comprise the complete IP packet.

When you send an e-mail across the Internet, all your text is bundled into packets and sent on to its destination. A Deep Packet Inspection device literally has the ability to look inside those packets and read your e-mail (or whatever the content might be).

Products sold that use DPI are essentially specialized snooping devices that examine the content (pay load inside) of Internet packets. Other terms sometimes used to describe techniques that examine Internet data are packet shapers, layer-7 traffic shaping, etc.

How is Deep Packet Iinspection related to Net Neutrality?

Net Neutrality is that nobody has the right to filter content on the Internet. Deep packet inspection is a method used for Filtering. The Net Neutrality debate continues to rage.

Why do some Internet Providers use Deep Packet Inspection devices?

There are several reasons:

1) Targeted advertising – If a provider knows what you are reading, they can display content advertising on the pages they control, such as your login screen or e-mail account.

2) Reducing “unwanted” traffic — Many providers are getting overwhelmed by types of traffic that they deem as less desirable such as Bittorrent and other forms of peer-to-peer. Bittorrent traffic can overwhelm a network with volume. By detecting and redirecting the Bittorrent traffic, or slowing it down, a provider can alleviate congestion.

3) Block offensive material — Many companies or institutions that perform content filtering are looking inside packets to find, and possibly block, offensive material or web sites.

4) Government spying — In the case of Iran (and to some extent China), DPI is used to keep tabs on the local population.

When is it appropriate to use Deep Packet Inspection?

1) Full disclosure — Private companies/institutions/ISPs that notify employees that their Internet use is not considered private have the right to snoop, although I would argue that creating an atmosphere of mistrust is not the mark of a healthy company.

2) Law enforcement — Law enforcement agencies with a warrant issued by a judge would be the other legitimate use.

What is all the fuss about?

It seems that consumers are finally becoming aware of what is going on behind the scenes as they surf the Internet, and they don’t like it.

In this quote from Paul Stephens (of the Privacy Rights Clearinghouse), the message seems to be that his organization is focusing on the content advertising industry for now. Targeted advertising is certainly a great tool for marketers, but Mr. Stephens’ group believes this is a violation of federal law and has opened a class action suit against a company called NuBead and several other entities.

Not that we condone other forms of online snooping, but deep packet inspection is the most egregious and aggressive invasion of privacy out there….It crosses the line in a way that is very frightening.

Paul Stephens, director of policy and advocacy for the Privacy Rights Clearinghouse, as quoted in the E-Commerce Times on November 14, 2008. Read the full article here.

Recently, Comcast had their hand slapped for re-directing Bittorrent traffic:

Speaking at the Stanford Law School Center for Internet and Society, FCC Chairman Kevin Martin said he’s considering taking action against the cable operator for violating the agency’s network-neutrality principles. Seems Martin was troubled by Comcast’s dissembling around the BitTorrent issue, not to mention its efforts to pack an FCC hearing on Net neutrality with its own employees.

– Digital Daily, March 10, 2008. Read the full article here.

Later in 2008, the FCC came down hard on Comcast.

In a landmark ruling, the Federal Communications Commission has ordered Comcast to stop its controversial practice of throttling file sharing traffic.

By a 3-2 vote, the commission on Friday concluded that Comcast monitored the content of its customers’ internet connections and selectively blocked peer-to-peer connections.

Wired.com, August 1, 2008. Read the full article here.

To top everything off, some legal experts are warning companies practicing deep packet inspection that they may be committing a felony.

University of Colorado law professor Paul Ohm, a former federal computer crimes prosecutor, argues that ISPs such as Comcast, AT&T and Charter Communications that are or are contemplating ways to throttle bandwidth, police for copyright violations and serve targeted ads by examining their customers’ internet packets are putting themselves in criminal and civil jeopardy.

Wired.com, May 22, 2008. Read the full article here.

However, it looks like things are going the other way in the U.K. as Britain’s Virgin Media has announced they are dumping net neutrality in favor of targeting bittorrent.

The UK’s second largest ISP, Virgin Media, will next year introduce network monitoring technology to specifically target and restrict BitTorrent traffic, its boss has told The Register.

The Register, December 16, 2008. Read the full article here.

While the debate over deep packet inspection will likely rage on for years to come, APconnections made the decision to fully abandon the practice over two years ago, having since proved the viability of alternative approaches to network optimization. Network quality and user privacy are no longer mutually exclusive goals.

Canadian ISPs confess in mass to deep packet inspection Jan 22 2009 article from techspot

AT&T gets hammered for decision to block controversial site. July 2009

Excerpt:

7/26/2009 could mark a turning point in the life of AT&T, when the future looks back on history, as the day that the shady practices of an ethically challenged company finally caught up with them: traffic filtering, site banning, and lying about service packages can only continue for so long before the FCC, along with the bill-paying public, takes a stand.

Created by APconnections, the NetEqualizer is a plug-and-play bandwidth control and WAN/Internet optimization appliance that is flexible and scalable. When the network is congested, NetEqualizer’s unique “behavior shaping” technology dynamically and automatically gives priority to latency sensitive applications, such as VoIP and email. Click here for a full price list.

8 Responses to “What Is Deep Packet Inspection and Why the Controversy?”

  1. When is Deep Packet Inspection a good thing? « NetEqualizer News Blog Says:

    [...] control solutions over to behavior based shaping. Consequently we  had also completely disavowed Deep Packet Inspection, or has Ars Technica put it, “vendor throws deep packet inspection under the [...]

  2. NetEqualizer White Paper Comparison with Traditional Layer-7 (Deep Packet Inspection Products) « NetEqualizer News Blog Says:

    [...] the following sections, we will cover specifically when and where application shaping (deep packet inspection)  is used, how it can be used to your advantage, and also when it may not [...]

  3. Deep Packet Inspection Being Used To Target Iranians « NetEqualizer News Blog Says:

    [...] ArchivesNetEqualizer Field Guide to Network Capacity PlanningIs Your ISP Throttling Your Bandwidth?What Is Deep Packet Inspection and Why the Controversy?Using a Load Generator/Emulator to Test Your NetworkNetEqualizer Seminar Video HighlightsNine Tips [...]

  4. Deep Packet Inspection Abuse In Iran Raises Questions About DPI Worldwide « NetEqualizer News Blog Says:

    [...] ArchivesNetEqualizer Field Guide to Network Capacity PlanningIs Your ISP Throttling Your Bandwidth?What Is Deep Packet Inspection and Why the Controversy?Using a Load Generator/Emulator to Test Your NetworkNetEqualizer Seminar Video HighlightsNine Tips [...]

  5. Top tips to quantify the cost of WAN Optimization « NetEqualizer News Blog Says:

    [...] fairness techniques comparison with NetEqualizerHow Does NetEqualizer compare to Mikrotik What Is Deep Packet Inspection and Why the Controversy?About the NetEqualizer…A Detailed Case Study of Packet Shaper and NetEqualizerNetEqualizer Support [...]

  6. NetEqualizer provides Net Nuetrality solution for bandwidth control. « NetEqualizer News Blog Says:

    [...] And yet  in face of this controversy, several of our competitors continue to sell deep packet inspection devices to [...]

  7. john Says:

    just use some subversion techniques, ala http://www.inputoutput.io/how-to-subvert-deep-packet-inspection-the-right-way/

    no more DPI, sorry Iran and China :’(

  8. URL based shaping with your NetEqualizer « NetEqualizer News Blog Says:

    [...] Your T1, DS3, or Cable Internet Connection with an Optimizing ApplianceNetEqualizer Software UpdatesWhat Is Deep Packet Inspection and Why the Controversy?Can your ISP support Video for all?Comcast fairness techniques comparison with [...]


Leave a Reply