Abstract
On the surface, WLANs act the same as their wired counterparts, transporting data between network devices. However, there is one fundamental, and quite significant, difference: WLANs are based upon radio communications technology as an alternative to structured wiring and cables. Data is transmitted between devices through the air by utilizing radio waves. Devices that participate in a WLAN must have a network interface card (NIC) with wireless capabilities. This essentially means that the card contains a small radio device that allows it to communicate with other wireless devices within the defined range for that card, for example, the 2.4-2.4853 GHz range. For a device to participate in a wireless network, it must firs be permitted to communicate with the devices in that network and, second, it must be within the transmission range of the devices in that network. To communicate, radio-based devices take advantage of electromagnetic waves and their ability to be altered in such a manner that they can carry information, known as modulation (Vines, 2002). Here we discuss wireless security mechanisms.
Key Terms in this Chapter
Wireless Access Point (AP): An access point (AP) is a piece of hardware that connects wireless clients to a wired network. It usually has at least two network connections and the wireless interface is typically an onboard radio or an embedded PCMCIA wireless card.
Wireless Network Interface Cards (NICs): Each NIC has a unique media access control (MAC) address burned into it at manufacture, to uniquely identify it; it also contains a small radio device and an antenna. However, the NIC must be compatible with the AP before communication can occur. For example, an 802.11b card needs an 802.11b AP.
Jamming: Jamming is a simple, yet highly effective method of causing a DoS on a wireless LAN. Jamming, as the name suggests, involves the use of a device to intentionally create interfering radio signals to effectively “jam” the airwaves, resulting in the AP and any client devices being unable to transmit.
Wired Equivalent Privacy: WEP was designed to provide the security of a wired LAN by encryption through use of the RC4 (Rivest Code 4) algorithm. Its primary function was to safeguard against eavesdropping (“sniffing”), by making the data that are transmitted unreadable by a third party who does not have the correct WEP key to decrypt the data
War Driving: War-driving is a term used to describe a hacker, who, armed with a laptop, a wireless NIC, an antenna, and sometimes a GPS device, travels, usually by car, scanning or “sniffing” for WLAN devices, or more specifically, unprotected or “open” and easily accessed networks.
Frequency Hopping Spread Spectrum (FHSS): Here the signal hops from frequency to frequency over a wide band of frequencies. The transmitter and receiver change the frequency they operate on in accordance with a pseudo-random sequence (PRS) of numbers. To properly communicate, both devices must be set to the same hopping code.
Direct Sequence Spread Spectrum (DSSS): DSSS combines a data signal with a higher data rate bit sequence, referred to as a “chipping code.”. The data are exclusive ORed (XOR) with a PRS which results in a higher bit rate, This increases the signal’s resistance to interference.
IEEE 802.11 Standards: IEEE has developed several specifications for WLAN technology, the names of which resemble the alphabet. There are basically two categories of standards
Denial of Service: A denial of service (DoS) attack is an incident in which a user or organization is deprived of the services of a resource they would normally expect to have. Typically, the loss of service is the inability of a particular network service to be available or the temporary loss of all network connectivity and services