Deep Packet Inspection and Privacy
Deep Packet Inspection ("DPI") is a computer network packet filtering technique that involves the inspection of the contents of packets as they are transmitted across the network. DPI is sometimes referred to as "complete packet inspection." Owing to the volume of traffic on most networks, DPI is usually automated and performed by software based on criteria set by the network operator. Deep Packet Inspection can be used to determine the contents of all unencrypted data transferred over a network. Since most Internet traffic is unencrypted, DPI enables Internet Service Providers ("ISPs") to intercept virtually all of their customers' Internet activity, including web surfing data, email, and peer-to-peer downloads. After inspecting the contents of users' packers, ISPs can use DPI to perform activities based on filter criteria. Deep Packet Inspection has been used in attempts to: build profiles of consumers for marketing purposes; intercept communications at the request of law enforcement (both with and without warrants); enforce copyright laws; prioritize the transmission of some packets over others; and identify computer viruses and spam. DPI also enables non-ISP service providers, such as search engines or webmail providers, to build user profiles based on Internet activity. Traditionally, packet headers are inspected by ISPs for a variety of reasons, including optimization of packet routing, detection of network abuse, and statistical analysis. Such inspection, sometimes referred to as "shallow packet inspection," gives ISPs access to basic information about Internet traffic, but does not disclose the contents of users' email or web surfing to ISPs. In contrast, Deep Packet Inspection provides ISPs with access to the content of all unencrypted Internet traffic that ISP customers send or receive. In the early days of the Internet, DPI was effectively impossible to perform on a large scale as a result of limited computing speed and resources. Recent technological advances have made is possible for ISPs and service providers to implement Deep Packet Inspection on a large scale. Deep Packet Inspection is controversial, and has been criticized by privacy and network neutrality advocates.
NebuAd plans to install its hardware on Charter’s system, and pay Charter a monthly fee per subscriber. NebuAd also pays various Internet advertising networks for the right to serve ads through their networks. NebuAd serves ads for its clients via the advertising networks, and makes a profit because NebuAd charges its clients more than it pays the ad networks. This differential is based on NebuAd’s ability to target advertisements to users’ interests based on user data that it collects through its hardware connected to Charter’s ISP servers. NebuAd’s hardware runs proprietary software that inspects the contents and header information of every packet transmitted to or from Charter’s subscribers. Based on the intercepted information, NebuAd builds profiles of users, and serves targeted advertisements to users through the ad networks. Charter does not obtain written consent from users prior to initiating DPI. Charter permits users to opt out of receiving targeted advertising via a cookie, but reportedly provides no mechanism for opting out of the Deep Packet Inspection. Charter’s Deep Packet Inspection program is the first large-scale DPI implementation by a major US ISP. Previously, several smaller American ISPs (including Knology, Wide Open West, and Embarq) instituted DPI programs. In early 2008, Deep Packet Inspection in the UK was met with public outcry. Three large British Internet providers, Virgin Media, BT and TalkTalk, contracted with Phorm to implement DPI-based targeted advertising. Privacy advocates and consumers objected, and additional controversy ensued when it was revealed that BT had used Phorm to secretly intercept customer information in 2006 and 2007. Google, Inc.'s Gmail webmail service utilizes Deep Packet Inspection to display advertisements based on email content. Gmail uses the inspection of email content to present targeted advertisements to Gmail users. The practice drew criticism from privacy advocates in the wake of Gmail's 2004 launch.
On April 24, 2008, the Canadian Association of Internet Providers asked the Canadian Radio-television and Telecommunications Commission to direct Bell Canada to cease "throttling" or "traffic shaping" network traffic. CAIP alleged that Bell intentionally reduced the data transfer speeds of other ISPs. Net Neutrality advocates have argued that Deep Packet Inspection permits network discrimination of the sort identified by CAIP, and thereby limits consumer choice, economic opportunity, and technological innovation.
Last Updated:
August 4, 2008
Page URL: http://epic.org/privacy/dpi/