Bluetooth Devices Interview Preparation Guide

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Cabir worm is one of the malicious software, usually referred as malware. It utilizes Bluetooth technology for sending itself to another similarly vulnerable device. As it is self-replicative, is it classified as a worm.
Cabir worms are currently affects mobile phone which uses the Symbian Series 60 User Interface Platform and feature Bluetooth wireless technology.

Denial Of Service attack. It attempts for making computer resources unavailable to its intended users. Its concerted efforts of a person are to prevent a site or service from functioning efficiently, temporarily or indefinitely. The target site categories are banks, credit card payment gateways and root name servers.

Sending messages by intruder to a computer system with an IP address that indicates the message is sent from a trusted host, for gaining unauthorized access to computer systems. The hacker/intruder first utilize a variety of techniques for finding an IP address of a trusted host. Later he modifies the packet headers, in order to give an illusion that the packets are sent from the host.

Bluetooth dongle is a technology that enables a PC for point to multi-point friendly connectivity with other similar Bluetooth devices, like PDA, mobile phone. The devices enable the communication between devices within a range of 30 feet apprx.
Certain recent desktops and laptops are built-in with Bluetooth dongle to communicate. Bluetooth enables a single adapter to allow multiple devices for communicating with one system to another.

Order to describe the way of implementing user models accomplishments, the profiles are developed. A number of user scenarios are described by the user models where Bluetooth performs the radio transmission. Profile stack describes the options in each protocol which are mandatory for each profile, and defines range of parameters for each protocol. The profiles are concerned for decreasing the risk of interoperability issues among various products of different manufacturers.

Device Power Class, Max Output Power (mW), Max Output Power (dBm), Expected Range
Class 1, 100mW, 20dBm, 100m
Class 2, 2.5mW, 4dBm, 10m
Class 3, 1mW, 0dBm, 10cm

Lightweight Directory Access Protocol is one of the directory service protocols. It runs over TCP/IP. LDAP directory services implements a client/server model. Directory data is available on one or more LDAP servers. The server responds with a pointer to another LDAP server.
Uses:
LDAP allows the users to access the information in the directory to change. Online telephone directories and email directories are some of the uses of LDAP. LDAP directory has utilities to modify, delete, and search the entries.

Connectivity:
One-to-one connections are made by infrared devices, while Bluetooth devices can form when all the devices have identified themselves to each other.

Versatility:
Bluetooth devices could work together; where as infrared devices need to be specially designed for specific devices.

Range:
Class 3 Bluetooth devices works at about 30 feet; while infrared is rated at 3 feet.

Orientation:
Infrared devices are direct line-of-sight; where as Bluetooth devices could communicate even in times of separation by obstacles. Security: Bluetooth is less secure than infrared due to the omni directional nature; where as infrared signals could only be intercepted by a device.

Multiple data links are combined for the formation of a single traffic engineering link, for the purpose of scale ability. The in-band messaging is not restricted by the management of TE links, but can be utilized by using out-of-band techniques.
The Link Management Protocol runs between a pair of nodes and is utilized for managing TE links. LMP is specifically used for maintaining control channel connectivity, verifying the physical connectivity of the data links, correlating the link property information, suppressing downstream alarms and localizing the link failures for protection/restoration purposes.

In Bluetooth piconet of master and slave devices, the slaves communicate only with the master device, not with other slaves. Piconet comprised of one master and up to seven slaves, think of a star topology with the master in the center and links spanning out to the slave devices. Hope this helps.

Companies likely to adopt this technology include, but are not limited to, software developers, network vendors, silicon vendors, peripheral and camera manufacturers, mobile PC and handheld device manufacturers, consumer electronics manufacturers and more.

Global technology leaders Ericsson, Nokia, IBM, Intel and Toshiba founded the Bluetooth SIG in 1998. These companies are now supported by over 1,000 other organizations with a wide range of expertise, including Widcomm, Inc.

Yes. They have to. The Bluetooth Logo Certification Program requires Bluetooth products to interoperate with products manufactured by other vendors; those products that don’t interoperate will not be allowed to use the Bluetooth logo.

Yes. One concern for mobile computing users is power consumption. Bluetooth radios are very low power, drawing as little as 0.3mA in standby mode and 30mA during sustained data transmissions. Bluetooth radios alternate among power-saving modes in which device activity is lowered to maximize the mobile power supply.

The Bluetooth specification 1.0 describes the link encryption algorithm as a stream cipher using 4 LFSR (linear feedback shift registers). The sum of the width of the LFSRs is 128, and the spec says “the effective key length is selectable between 8 and 128 bits”. This arrangement allows Bluetooth to be used in countries with regulations limiting encryption strength, and “facilitate a future upgrade path for the security without the need for a costly redesign of the algorithms and encryption hardware” according to the Bluetooth specification. Key generation and authentication seems to be using the 8-round SAFER+ encryption algorithm. The information available suggests that Bluetooth security will be adequate for most purposes; but users with higher security requirements will need to employ stronger algorithms to ensure the security of their data.

Bluetooth is designed for very low power use, and the transmission range will only be 10m, about 30ft. High-powered Bluetooth devices will enable ranges up to 100m (300ft). Considering the design philosophy behind Bluetooth, even the 10m range is adequate for the purposes Bluetooth is intended for. Later versions of the Bluetooth spec may allow longer ranges.

Bluetooth transfers data at a rate of 721 Kbps, which is from three to eight times the average speed of parallel and serial ports, respectively. This bandwidth is capable of transmitting voice, data, video and still images

No, both Bluetooth and WLAN can co-exist. Since Bluetooth devices use Frequency Hopping and most WLANs use Direct Sequence Spreading techniques they each appear as background noise to the other and should not cause any perceivable performance issues.

No. Bluetooth radios operate on the unlicensed 2.4 GHz (Industrial, Scientific and Medical) frequency band that is shared among other devices (microwave ovens, cordless phones, garage door openers, etc. ). Bluetooth radios switch frequencies at such a rapid pace (1,600 times per second) and the data packets are so small that interference from other RF sources is highly unlikely. Bluetooth is a robust communication system.

Versions 1.0 and 1.0 B had numerous problems and the various manufacturers had great difficulties in making their products interoperable. 1.0 and 1.0B also had mandatory Bluetooth Hardware Device Address (BD_ADDR) transmission in the handshaking process, rendering anonymity impossible at a protocol level, which was a major setback for services planned to be used in Bluetooth environments, such as Consumerism.

Bluetooth is a radio standard and communications protocol primarily designed for low power consumption, with a short range (power class dependent: 1 meter, 10 meters, 100 meters) based around low-cost transceiver microchip in each device.

Bluetooth lets these devices communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, so long as the received power is high enough.

A profile is a description of how to use a specification to implement a particular function. The International Standards Organization (ISO) first came up with the idea of profiles. In Bluetooth, there are several profiles available and they are arranged in a hierarchical fashion. For example, in order to use the headset profile, a device must also include the lower level profiles such as the serial port and general access profiles.

Depending on the Bluetooth profiles included on the device, Bluetooth technology has the capability to wirelessly synchronize and transfer data among devices. The Bluetooth audio capabilities can be used for headset and hands free applications. The exact functionality provided by a Bluetooth enabled device depends on the Bluetooth profiles included.

The 802.11b (WiFi) standard is commonly used for wireless networking. Bluetooth is not a competitor with 802.11b, but rather a complement to it. While 802.11b is generally a replacement for wired local area networking, Bluetooth is more commonly used as a replacement for cables between individual devices. Bluetooth is designed to link devices within a very short range (up to 33 feet ). Bluetooth is part of the 802.15 standard.

Bluetooth was initiated by Ericsson, IBM, Intel, Nokia and Toshiba in early 1998. These companies later formed a special interest group known as the Bluetooth SIG. The Bluetooth 1.0 specifications were released on July 26, 1999, but the technology has only recently become inexpensive enough for widespread use.