By Mathew J. Schwartz

Is the next-generation Internet protocol, known as IPv6, a privacy time bomb? To be sure, the increasing adoption of the protocol has triggered warnings about its potential to compromise the privacy of Internet users.

"Perhaps the most commonly identified privacy issue associated with IPv6 is the ability to embed a network device's Ethernet MAC address in an IPv6 address," said Bill Cerveny, a senior software quality assurance engineer at network security firm Arbor Networks in Chelmsford, Mass.

Since every MAC address is unique, that means IPv6 could allow individual devices to be fingerprinted and uniquely identified, as Bill Frezza of Adams Capital Management warned in a 1999 article for Internet Week, "Where's All the Outrage about IPv6 Privacy?" Of course, such fingerprinting could be used--or misused--by everyone from online behavior tracking firms to law enforcement agencies.

But why is a decade-old privacy warning still a concern? Primarily because almost no one has rushed to adopt IPv6. Indeed, since the Internet Engineering Task Force (IETF) published the official IPv6 standard in 2003, uptake has been slow, and the answers to tricky privacy questions thus postponed.

Networking Standard Evolves, In Theory

Since 2003, to be fair, the IETF has actively addressed IPv6-related privacy and security concerns, such as worries over the traceability of static IPv6 addresses. For example, in 2007, it released for comment "Privacy Extensions for Stateless Address Autoconfiguration in IPv6," detailing techniques for assigning temporary IPv6 address values. (Similar capabilities exist with IPv4, but their use is likewise optional.) Over time, these temporary values would be reassigned to different machines, an approach which the IETF said "makes it more difficult for eavesdroppers and other information collectors to identify when different addresses used in different transactions actually correspond to the same node."

As that guidance suggests, however, IPv6 is an engineering standard. How it gets applied remains to be seen. Indeed, "the implementation of the privacy-sensitive features is largely dependent on the operating system vendor, network administrator and even on the individual device user," said Cerveny.

From Apathy to Adoption

The decade of IPv6 adoption apathy is starting to end. On June 8, 2011, "IPv6 Day" featured the first trial, on a global scale, of the networking protocol. Notably, more than 400 sites, including Akamai, Facebook, Google and Yahoo, enabled native IPv6 on their servers, and by all accounts it went smoothly, although accounted for only a negligible amount of actual Internet traffic that day.

Still, the event was reassuring, since the previous protocol, IPv4, can only support about four billion IP addresses, and they've now mostly been assigned. In contrast, IPv6 can facilitate a mind-boggling quantity of IP addresses--some 340 trillion trillion trillion. Meanwhile, it also brings networking and security benefits, including better traffic routing and address allocation. It also eliminates the need to use network address translation (NAT), which had helped extend the life of IPv4 by separating IP addresses from the Ethernet addresses inside the corporate LAN. Now, every device can have its own IP.

Privacy and Accountability Concerns

That feature, however, also poses security and privacy concerns. Today, NAT means that nodes inside a corporate network typically get screened from entities outside the network, which has security upsides. But in an IPv6 environment, nodes might connect directly to the Internet, and thus be more directly exposed to malicious operators. As a result, businesses that adopt IPv6 will need to master new security strategies.

Unfortunately, the state of IPv6-related security lags. According to Arbor Networks, most networking equipment--routers, switchers and some firewalls--is ready to make the logical jump to handling IPv6. But many security products, such as intrusion detection systems, won't yet work in an IPv6 environment.

Another issue is that IPv6 was designed to make some IPv4 features, such as Dynamic Host Configuration Protocol (DHCP), unnecessary. “The problem we have had...is that Indiana University’s specific IPv4 accountability method, using DHCP, was built specific to IPv4 technologies that are not identical in IPv6,” said Indiana University’s chief privacy officer and compliance coordinator, Merri Beth Lavagnino, CIPP, CIPP/IT. “Higher education relies a lot on DHCP for accountability.” Accordingly, the university’s accountability system will have to be redesigned for IPv6, but short of adopting network access control technology or some type of persistent Web cookie-- neither of which the university is prepared to do--the solution isn’t clear.

IP Addresses: Personally Identifiable Information?

Consumers face a slightly different scenario, in that service providers might assign static IP addresses to customers, meaning that Internet connections and behavior could be more easily traced back to actual people, unless new types of legal protections are enacted.  

Currently, some countries--including most of the European Union--treat IP addresses as personal information, although others don't. For example, according to a 2009 decision from U.S. District Court Judge Richard Jones: "In order for 'personally identifiable information' to be personally identifiable, it must identify a person. But an IP address identifies a computer." Similarly, in 2010, a French court broke with the EU and ruled that IP addresses don't constitute personal information.

Of course, those cases also revolved around the technical capabilities of IPv4. Once IPv6 reaches widespread adoption, existing legal decisions will likely face new challenges.

IPv6 Shakedown Could Take Years

First, however, people actually have to start using IPv6 en masse. According to IPv6 guru Cricket Liu, vice president of architecture for Infoblox, it could take another five or 10 years before IPv6 adoption reaches maturity. In the interim, companies face potential hiccups from having to run mixed IPv4 and IPv6 networks, as well as figuring out how IPv6 really works.

Along the way, expect new surprises of the security- and privacy-compromising kind. For example, last year researchers disclosed that people relying on the most widely used type of VPN services, which are based on PPTP (point-to-point tunneling protocol), could still be uniquely identified when using IPv6. That's worrying, since many businesses, and some consumers, rely on VPN to secure and obscure their Internet activities.

Most IPv6-related security concerns, however, will likely be more mundane, if no less dangerous. For example, one tried-and-true technique for hacking into corporate networks is to find and exploit misconfigurations, for example in firewalls. The same will be true with IPv6, although arguably the number of misconfigurations to exploit will rise sharply, as networking engineers learn their way around the new protocol.

Another oft-heard IPv6 concern is how it might be exploited for online behavioral tracking, as practiced by online advertisers who rely on cookies and sometimes quasi-legal, persistent tracking technologies. Given the relatively low level of IPv6 deployment so far, however, it's too soon to know the answer to that question.

In fact, the same can be said for IPv6 and virtually any related privacy concern. "Much will depend upon how IPv6-enabled networks are ultimately designed and deployed," said Arbor's Cerveney.

Mathew Schwartz reports on information security and privacy issues for InformationWeek and The Privacy Advisor. 


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