Blog: Sniffing for Patent Infringement

by: Billy Raska, Associate Staff

Starting back in 2011, Innovatio IP Ventures, LLC (“Innovatio”) began suing various hotels, coffee shops, restaurants, supermarkets, and other commercial Wi-Fi users for infringing several patents that it had acquired from Intermec Technologies Corporation and Intermec IP Corporation, Norand Corporation, and Broadcom Corporation.[1] Most of the publicity surrounding this case has focused on the fact that Innovatio is a non-practicing entity and that the act of suing companies for merely using Wi-Fi is an abusive use of the patent system.[2] However, it is equally interesting to examine how Innovatio has gone about discovering the alleged infringement of its patents.

Innovatio sent technicians to the premises of the various hotels, coffee shops, restaurants, and supermarkets that it ultimately sued with a laptop and a Riverbed AirPcap Nx packet capture adapter[3] (or another similar device). The technicians analyzed only the headers of captured Wi-Fi packets using a modified version of Wireshark [4]. On August 22, 2012, in a preliminary ruling on the admissibility of the information that Innovatio had obtained through its Wi-Fi sniffing process, Judge Holderman held that “Innovatio may collect information from the defendants’ public-facing Wi–Fi networks according to its proposed protocol.”[5]

In reaching this conclusion, Judge Holderman examined the potential privacy concerns raised under the Federal Wiretap Act and ultimately found that “Innovatio’s proposed protocol falls into the exception to the Wiretap Act allowing a person ‘to intercept or access an electronic communication made through an electronic communication system that is configured so that such electronic communication is readily accessible to the general public.’”[6] Judge Holderman relied heavily on the fact that the Riverbed AirPcap Nx packet capture adapter is available to the public to purchase for $698 and the Wireshark software can be downloaded for free. Furthermore, Riverbed offers a more basic packet capture adapter for $198. Therefore, the information that Innovatio obtained was readily accessible because the technology used to obtain it was readily accessible to the general public.

A further analysis of the technology involved here reveals that Judge Holderman could have made an even stronger argument on this point. “[A]ll Wi–Fi devices necessarily store an entire received data packet, including the packet’s substantive communications, while the device processes the packet.”[7] These packets are then subjected to several different types of filters that are used to determine whether or not the packet is addressed to the particular Wi-Fi device. There are two types of filters that are of particular interest here: the first filter is used to determine whether or not the packet was sent on the same Wi-Fi network and the second filter is used to determine whether or not the packet is addressed to the particular Wi-Fi device.[8]

The first filter can be avoided by placing a device in “monitor mode.”[9] Some newer Linux machines have monitor mode functionality built in and for those computers that do not, devices such as the Riverbed AirPcap Nx packet capture adapter can be used.

The second filter can be avoided by placing a device in “promiscuous mode.”[10] This can be achieved by simply checking a box in the Wireshark software. Therefore, once a computer is connected to a Wi-Fi network, Wireshark can be used to capture packets on that Wi-Fi network that are not intended for that computer due to the underlying implementation of Wi-Fi.

This all goes to show that capturing Wi-Fi packets in today’s day and age is very easy to accomplish. There are several benefits to having the ability to place a device in monitor mode, but a lot can be accomplished in promiscuous mode. Innovatio targeted commercial entities that provided an open Wi-Fi network for customers. Anyone connected to one of those open Wi-Fi networks could have installed and run Wireshark in promiscuous mode in order to capture packets for FREE.

A point of concern is that Judge Holderman did not rely at all on the fact that Innovatio only collected the header information of the packets because Innovatio’s protocol fell under an exception to the Federal Wiretap Act. This raises the question: could Innovatio have also collected the personal information that was associated with the captured packets? If so, then this opens the door for companies to use the techniques employed by Innovatio to discover a much wider range of patent infringement than may have been initially anticipated.