Office Surveillance: Locating And Tracking 802.11b

securitas writes "The NY Times recently ran an article about locating and tracking users of 802.11b WiFi networks in three dimensions using triangulation (Google) with multiple base stations. The goal is to create context-aware networks that can allocate bandwidth and provide location-based services such as uploading relevant information to a PDA. The article can be seen in a new light when coupled with the growth in workplace surveillance of employees by corporate executives (Google / short version at IHT) and the associated practical, ethical and legal problems. Interlink Networks 802.11 wireless detection and tracking white paper (PDF)." (This seems as good a place as any to mention Kensington's handheld 802.11 detector; they claim it to be the only such device on the market today. This is the cheapest detector I've seen; have the others all disappeared?)

Comments

Re:How well does this work in indoor environments?

[Rosco P. Coltrane]

Triangulation traditionally relies on measuring distance through signal strengths and so is limited to an outdoor environment, where the signal loss per kilometer can be predicted with much greater accuracy than in an indoor environment.

Where did you get that ?

Triangulation works by being in 2 or 3 different locations, determining what direction the signal comes from with a directional antenna at each location, then drawing the lines on a map and see where they intersect. It'a called triangulation because it draws a triangle on the map. It has nothing to do with signal stength.

Slightly OT, but here's a nice OSS tool...

[pen]

AirTrafis a 100% passive packet sniffing tool for the wireless 802.11b networks. It captures and tracks all wireless activity in the coverage area, decodes packets, and maintains acquired information associated by access points, as well as detected individual wireless nodes. It dynamically detects any access points in the area, finds association between wireless clients and access points, and builds information table for each packet that is transmitted via the air. AirTraf is able to maintain packet count, byte information, related bandwidth, as well as signal strength of nodes.

This has been around for a while

[Jarit99]

The same discussion seems to be popping up every 6 months or so. Check out what companies such as Ekahau and BlueSoft are offering.

Re:How well does this work in indoor environments?

[Anonymous Coward]

Almost.

TRIangulation works exactly as you say (except the tri means 3 measurements only). Multiangulation uses >3 measurements in the same way.

When you have ranges (i.e. distances as derived from signal attenuation), it's called lateration. Trilateration == 3 ranges. Multilateration == >3 ranges.

However, triangulation is commonly used when lateration is meant, just because people are more familiar with the term.

Real life example

[alanjstr]

This article on Computerworld talks about tracking down unauthorized access points.

Re:Prices and usefulness

[naner42]

Best Buy carries them, but it seems like they may be selling quickly. They should be back in the computer department with all of the cheesy laptop accessories (ie. USB fans, lights, etc.). My local store had several but I've heard complaints that other stores sell out quickly.