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Counseling Astrology Advice | Tarot Advice | Parenting Dating Advice | Love Advice | Divorce Advice Legal Advice | Debt Advice | Career Advice W IRELESS N ETWORK S ECURITY 4-1 4. Wireless Personal Area Networks This section provides a detailed overview of Bluetooth technology--an ad hoc networking technology. As mentioned earlier, ad hoc networks are a relatively new paradigm of wireless communications in which no fixed infrastructure exists such as base stations or access points. In ad hoc networks, devices maintain random network configurations formed "on the fly," relying on a system of mobile routers connected by wireless links that enable devices to communicate with each other. Devices within an ad hoc network control the network configuration, and they maintain and share resources. Ad hoc networks are similar to peer-to-peer (P2P) networking in that they both use decentralized networking, in which the information is maintained at the end user location rather than in a centralized database. However, ad hoc and P2P networks differ in that P2P networks rely on a routing mechanism to direct information queries, whereas ad hoc networks rely on the device hardware to request and share the information. Ad hoc networks allow devices to access wireless applications, such as address book synchronization and file sharing applications, within a wireless personal area network (PAN). When combined with other technologies, these networks can be expanded to include network and Internet access. Bluetooth devices that typically do not have access to network resources but that are connected in a Bluetooth network with an 802.11 capable device can achieve connection within the corporate network as well as reach out to the Internet. 4.1 Bluetooth Overview Ad hoc networks today are based primarily on Bluetooth technology. Bluetooth is an open standard for short-range digital radio. It is touted as a low-cost, low-power, and low-profile technology that provides a mechanism for creating small wireless networks on an ad hoc basis. Bluetooth is considered a wireless PAN technology that offers fast and reliable transmission for both voice and data. Untethered Bluetooth devices will eliminate the need for cables and provide a bridge to existing networks. Bluetooth can be used to connect almost any device to any other device. An example is the connection between a PDA and a mobile phone. The goal of Bluetooth is to connect disparate devices (PDAs, cell phones, printers, faxes, etc.) together wirelessly in a small environment such as an office or home. According to the leading proponents of the technology, Bluetooth is a standard that will ultimately-- ! Eliminate wires and cables between both stationary and mobile devices ! Facilitate both data and voice communications ! Offer the possibility of ad hoc networks and deliver synchronicity between personal devices. Bluetooth is designed to operate in the unlicensed ISM (industrial, scientific, medical applications) band that is available in most parts of the world, with variation in some locations. The characteristics of Bluetooth are summarized in Table 4-1. Bluetooth-enabled devices will automatically locate each other, but making connections with other devices and forming networks requires user action. As with all ad hoc networks, Bluetooth network topologies are established on a temporary and random basis. A distinguishing feature of Bluetooth networks is the master-slave relationship maintained between the network devices. Up to eight Bluetooth devices may be networked together in a master-slave relationship, called a "piconet." In a piconet, one device is designated as the master of the network with up to seven slaves connected directly to that network. The master device controls and sets up the network (including defining the network's hopping scheme). Devices in a Bluetooth piconet operate on the same channel and follow the same frequency hopping sequence. Although only one device may perform as the |
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