How Does Wireless Work?

A wireless LAN is a collection of two or more devices connected via open air for the purpose of sharing data. A wireless network can be put together in many ways. 802.11 wireless local area networks (WLANs) typically communicate between stations and access points (APs) using radio waves such that line-of-sight communication (an unobstructed path) between the access point and the wireless station is not required. The most widely accepted and common standard for wireless networking is the IEEE 802.11b protocol. Other standards such as Bluetooth also exist, but 802.11b is enjoying the most commercial success.

New technology that is being developed for wireless access uses the new 802.11a wireless standard. 802.11a is faster than 802.11b, which has data-transfer rates of 54Mbps. Intel, along with Proxim and Enterasys Networks, plans to release products based on 802.11a. Companies such as Cisco Systems and Agere Systems (3Com and Symbol) dominate the market with 802.11b technology, but that should change over the next year as 802.11a technology makes it to the market place. The two wireless standards are not compatible, but they both have security flaws in common.

Access Points

An access point (AP) is a piece of hardware that acts as a bridge between the wireless “network cloud” and the wired network. A wireless network that is installed with access points allows the user to roam about while maintaining his connectivity (see Figure 14.3). When a user travels outside of the AP's range, connectivity to the network is lost. Organizations frequently put up multiple APs so that people can roam about the premises and maintain connectivity. Figure 14.3 shows just one way an access point is used in a wireless LAN.

In terms of hardware, wireless LAN cards are installed in client workstations, laptops, or PDAs that allow the clients to communicate through the access point to the wired network and its resources.

Ad Hoc Network

A wirelessnetwork composed only of stations without access points can be considered an ad hoc network (see Figure 14.4). This type of network can be used anywhere. Few requirements are necessary for this setup to work. An ad hoc network could potentially be the most dangerous of all wireless networks. Because this type of network is going to be set up on-the-fly when two people want to share data, it is more probable that less consideration is going to be placed on security. The user might set it up “just to get the job done” and forget, for example, that he is broadcasting traffic with his wireless network card.