Deploying Secure 802.11 Wireless Networks with Microsoft Windows
Chapter 1
IEEE 802.11 Overview
Before getting into the technical details of the Institute of Electrical and Electronic Engineers (IEEE) 802.11 standard, it is helpful to review the benefits of wireless LAN networking, which include the following:
Wireless connections can extend or replace a wired infrastructure in situations where it is costly, inconvenient, or impossible to lay cables. This benefit includes the following:
To connect the networks in two buildings separated by a physical, legal, or financial obstacle, you can either use a link provided by a telecommunications vendor (for a fixed installation cost and ongoing recurring costs) or you can create a point-to-point wireless link using wireless LAN technology (for a fixed installation cost, but no recurring costs). Eliminating recurring telecommunications charges can provide significant cost savings to corporations.
Wireless LAN technologies can be used to create a temporary network, which is in place for only a specific amount of time. For example, the network needed at a convention or trade show can be a wireless network, rather than deploying the physical cabling required for a traditional Ethernet network.
Some types of buildings, such as historical buildings, might be governed by building codes that prohibit the use of wiring, making wireless networking an important alternative.
The wiring-free aspect of wireless LAN networking is also very attractive to homeowners who want to connect the various computers in their home together without having to drill holes and pull network cables through walls and ceilings.
Increased productivity for the mobile employee. This benefit includes the following:
The mobile user whose primary computer is a laptop or notebook computer can change location and always remain connected to the network. This enables the mobile user to travel to various places meeting rooms, hallways, lobbies, cafeterias, classrooms, and so forth and still have access to networked data. Without wireless access, the user has to carry cabling and is restricted to working near a network jack.
Wireless LAN networking is a perfect technology for environments where movement is required. For example, retail environments can benefit when employees use a wireless laptop, palmtop, or computer to enter inventory information directly into the store database from the sales floor.
Even if no wireless infrastructure is present, wireless laptop computers can still form their own ad hoc networks to communicate and share data with each other.
Easy access to the Internet in public places.
Beyond the corporate campus, access to the Internet and even corporate sites can be made available through public wireless hot spot networks. Airports, restaurants, rail stations, and common areas throughout cities can be provisioned to provide this service. When the traveling worker reaches his or her destination, perhaps meeting a client at the corporate office, limited access can be provided to the user through the local wireless network. The network can recognize the user from another corporation and create a connection that is isolated from local corporate network but provides Internet access to the visiting user. Wireless infrastructure providers are enabling wireless connectivity in public areas around the world. Many airports, conference centers, and hotels provide wireless access to the Internet for their visitors.
NOTE In all these wireless LAN scenarios, it is worth noting that today s standards-based wireless LANs operate at the same speeds that were considered state of the art for wired networks just a few years ago. For example, IEEE 802.11b, a prevalent wireless LAN technology, operates at a maximum of 11 megabits per second (Mbps), or about 30 to 100 times faster than standard dial-up technologies. This bandwidth is certainly adequate to deliver acceptable throughput for a number of applications or services. In addition, ongoing advancements with these wireless standards continue to increase the bit rate, with speeds of up to 54 Mbps.
Although IEEE 802.11 wireless LAN technologies provide these benefits, they also introduce security challenges with regard to who is allowed to connect and how they must send wireless traffic. These security challenges and their solutions are described in detail in Chapter 2, Wireless Security.