Bluetooth

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances
(using short wavelength radio transmissions) from fixed and mobile devices, creating personal area
networks (PANs) with high levels of security. Created by telecoms vendor Ericsson in 1994,[1] it was
originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices,
overcoming problems of synchronization. Today Bluetooth is managed by the Bluetooth Special Interest
Group.

Communication and connection

A master Bluetooth device can communicate with up to seven devices in a piconet. The devices
can switch roles, by agreement, and the slave can become the master at any time.

At any given time, data can be transferred between the master and one other device (except for
the little-used broadcast mode). The master chooses which slave device to address; typically, it
switches rapidly from one device to another in a round-robin fashion.

The Bluetooth Core Specification provides for the connection of two or more piconets to form a
scatternet, in which certain devices serve as bridges, simultaneously playing the master role in
one piconet and the slave role in another.

Many USB Bluetooth adapters or "dongles" are available, some of which also include an IrDA
adapter. Older (pre-2003) Bluetooth dongles, however, have limited capabilities, offering only
the Bluetooth Enumerator and a less-powerful Bluetooth Radio incarnation. Such devices can
link computers with Bluetooth with a distance of 100 meters, but they do not offer much in the
way of services that modern adapters do.

Bluetooth Piconets

Let's say you have a typical modern living room with typical modern stuff inside. There's an
entertainment system with a stereo, a DVD player, a satellite TV receiver and a television; there's
also a cordless telephone and a personal computer. Each of these systems uses Bluetooth, and
each forms its own piconet to talk between the main unit and peripheral.

The cordless telephone has one Bluetooth transmitter in the base and another in the handset. The
manufacturer has programmed each unit with an address that falls into a range of addresses it
has established for a particular type of device. When the base is first turned on, it sends radio
signals asking for a response from any units with an address in a particular range. Since the
handset has an address in the range, it responds, and a tiny network is formed. Now, even if one
of these devices should receive a signal from another system, it will ignore it since it's not from
within the network. The computer and entertainment system go through similar routines,
establishing networks among addresses in ranges established by manufacturers. Once the
networks are established, the systems begin talking among themselves. Each piconet hops
randomly through the available frequencies, so all of the piconets are completely separated from
one another.

Now the living room has three separate networks established, each one made up of devices that
know the address of transmitters it should listen to and the address of receivers it should talk to.
Since each network is changing the frequency of its operation thousands of times a second, it's
unlikely that any two networks will be on the same frequency at the same time. If it turns out that
they are, then the resulting confusion will only cover a tiny fraction of a second, and software
designed to correct for such errors weeds out the confusing information and gets on with the
network's business.

Bluetooth Security

In any wireless networking setup, security is a concern. Devices can easily grab radio waves out
of the air, so people who send sensitive information over a wireless connection need to take
precautions to make sure those signals aren't intercepted. Bluetooth technology is no different --
it's wireless and therefore susceptible to spying and remote access, just like WiFi is susceptible if
the network isn't secure. With Bluetooth, though, the automatic nature of the connection, which
is a huge benefit in terms of time and effort, is also a benefit to people looking to send you data
without your permission.

Bluetooth offers several security modes, and device manufacturers determine which mode to
include in a Bluetooth-enabled gadget. In almost all cases, Bluetooth users can establish "trusted
devices" that can exchange data without asking permission. When any other device tries to
establish a connection to the user's gadget, the user has to decide to allow it. Service-level
security and device-level security work together to protect Bluetooth devices from unauthorized
data transmission. Security methods include authorization and identification procedures that limit
the use of Bluetooth services to the registered user and require that users make a conscious
decision to open a file or accept a data transfer. As long as these measures are enabled on the
user's phone or other device, unauthorized access is unlikely. A user can also simply switch his
Bluetooth mode to "non-discoverable" and avoid connecting with other Bluetooth devices
entirely. If a user makes use of the Bluetooth network primarily for synching devices at home,
this might be a good way to avoid any chance of a security breach while in public.

Still, early cell-phone virus writers have taken advantage of Bluetooth's automated connection
process to send out infected files. However, since most cell phones use a secure Bluetooth
connection that requires authorization and authentication before accepting data from an unknown
device, the infected file typically doesn't get very far. When the virus arrives in the user's cell
phone, the user has to agree to open it and then agree to install it. This has, so far, stopped most
cell-phone viruses from doing much damage. See How Cell-phone Viruses Work to learn more.

Other problems like "bluejacking," "bluebugging" and "Car Whisperer" have turned up as
Bluetooth-specific security issues. Bluejacking involves Bluetooth users sending a business card
(just a text message, really) to other Bluetooth users within a 10-meter (32-foot) radius. If the
user doesn't realize what the message is, he might allow the contact to be added to his address
book, and the contact can send him messages that might be automatically opened because they're
coming from a known contact. Bluebugging is more of a problem, because it allows hackers to
remotely access a user's phone and use its features, including placing calls and sending text
messages, and the user doesn't realize it's happening. The Car Whisperer is a piece of software
that allows hackers to send audio to and receive audio from a Bluetooth-enabled car stereo. Like
a computer security hole, these vulnerabilities are an inevitable result of technological
innovation, and device manufacturers are releasing firmware upgrades that address new
problems as they arise.

If communications security is a concern of yours, then click here to learn how phone
conferencing security works. To learn more about Bluetooth security issues and solutions, see
Bluetooth.com: Wireless Security.

How Bluetooth Works

When you use computers, entertainment systems or telephones, the various pieces and parts of
the systems make up a community of electronic devices. These devices communicate with each
other using a variety of wires, cables, radio signals and infrared light beams, and an even greater
variety of connectors, plugs and protocols.

There are lots of different ways that electronic devices can connect to one another. For example:

 Component cables
 Electrical wires
 Ethernet cables
 WiFi
 Infrared signals

The art of connecting things is becoming more and more complex every day. In this article, we
will look at a method of connecting devices, called Bluetooth, that can streamline the process. A
Bluetooth connection is wireless and automatic, and it has a number of interesting features that
can simplify our daily lives.