Bluetooth Basics

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This article was published by ComputorEdge, issue #2507, 2007-02-16, as a feature article, in both their print edition (on pages 20-21) and their website.

When people hear the name "Bluetooth", if they are unfamiliar with wireless technology, then they may imagine that the name refers to a lesser-known pirate who once haunted the Caribbean sea lanes, sporting a false tooth made of blue opal, sapphire, or lapis lazuli. They might envision him strolling the upper decks of his ship, talking to a clever parrot that perched on his shoulder and whispered in his ear.

These people might be unfamiliar with the latest wireless terminology, but in a sense they are not too far from the truth, because in this current era of swashbuckling technology firms, we see an increasing number of people strolling the upper decks of the local mall, talking into the cleverly designed devices hooked onto — and talking into — their ears. To the uninitiated, they might appear to be Star Trek fans, outfitted with Borg-like personal communicators attached to their heads. But they are simply participants in the new Bluetooth trend.

Though unrelated to the adventures of the high seas, Bluetooth is a relatively new technology that uses short-range wireless communication to enable different types of devices to connect to one another and share information. These devices include laptops, personal digital assistants (PDAs), and cell phones. Bluetooth is being adopted by a growing number of high-tech companies, as well as high-tech consumers.

Talking the Same Language

Like so many other similar technologies, Bluetooth refers not only to the types of devices that make use of it, but also to the underlying technology that makes it possible, as well as the companies that are incorporating it into their products. The Bluetooth technical specification details how a device must structure, receive, and transmit the digital information, for it to be considered a legitimate Bluetooth device.

Think of it as a wireless communication protocol, in the same way that HTTP is a protocol that details how computers connected to the Internet must structure and address packets of information that, when combined, comprise such things as Web pages.

Just as HTTP-compliant computers are thus able to communicate with others on the global network, all Bluetooth-compliant devices are thus able to communicate with other Bluetooth devices within a Bluetooth network. One key difference of course is that the HTTP network is largely wired (such as the fiber-optic "backbone" cables), while Bluetooth networks — known as "piconets" — are entirely wireless.

Another difference between the Internet and any given piconet, is that a computer connected to the Internet can theoretically communicate with an unlimited number of other computers connected, albeit indirectly. But there is a limit of Bluetooth devices within any piconet. Hence, the wireless telephone user "walking the credit card plank" at the local mall, talking to a mate via the Bluetooth phone hooked to his ear, can at the same time connect with up to seven other Bluetooth devices within range.

For the purposes of illustration, let's assume that his phone is currently communicating with a total of seven other Bluetooth devices. In other words, his piconet is maxed out in size. Does this mean that any one of those other seven devices is limited to communicating with only this fellow's Bluetooth phone and the six other devices within his piconet? That would be an unwelcome restriction on each user's ability to choose what devices they want to communicate with at any one time.

Fortunately, the Bluetooth technology was developed so that there is no such limitation. In our example, if his mate is currently talking to him using her own Bluetooth phone, but it is not connected to any other devices in his piconet, then she is free to connect with up to seven other devices — thus forming her own piconet. She is then part of two separate piconets, and could theoretically participate in up to a total of seven of them.

Patter — Private or Pirate?

While some of these details are fairly technical, and could be confusing to the typical consumer, users of Bluetooth devices do not have to concern themselves with establishing their piconets in order to communicate with other Bluetooth users. In fact, piconets are established automatically as soon as a Bluetooth device gets within range of any other Bluetooth devices.

The actual distance depends which of three classes the particular Bluetooth devices belong to. Class 3 radios have a range of only 1 meter, while Class 1 radios have a range of up to 100 meters. Most mobile devices along to the Class 2 category, and have a range of about 10 meters.

This raises the issue of security. If the person sitting next to you in the mall's food court also has a Bluetooth phone, does that mean that they can easily listen to your conversation with someone else? Theoretically not, because Bluetooth has built-in security measures.

But are those security measures strong enough? It might be a mistake to assume so, given the growing number of reports online concerning individuals and groups hacking into Bluetooth connections. "Bluebugging" and "Bluesnarfing" might sound like exotic new forms of disease infection and eradication, but they instead refer to categories of hacking that allegedly take advantage of weaknesses in the security of Bluetooth authentication and data transfer.

Online Resources

To learn more about Bluetooth technology, perhaps the best place to start is the "Official Bluetooth Wireless Info Site", which offers introductory information concerning Bluetooth, a glossary, an outline of wireless uses, details on how companies can implement Bluetooth within their own products, and plenty of press releases and other materials aimed at the media.

Speaking of the press, the official site naturally presents only positive information about the technology. As one might expect, the site does not offer any how-to guides on Bluebugging or Bluesnarfing. Aspiring Bluetooth pirates will instead want to search the Internet using the appropriate key terms.

In doing so, they may stumble across such information as details on Bluetooth security flaws and attacks, including "Bluejacking"; Marcel Holtmann's Bluetooth/Linux how-to's; and the BlueZ Project, which hopes to develop a Bluetooth specification for Linux.

The wide range of Bluetooth-enabled products available is far beyond the scope of any single article. But one can get an idea of the tremendous number of such products that are being offered, simply by considering the major manufacturers who are onboard: Ericsson, Intel, Motorola, Nokia, and Toshiba. The list also includes Microsoft — certainly no stranger to its products being pirated.

Copyright © 2007 Michael J. Ross. All rights reserved.

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