Chapter 7 Wireless
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7.9.3.3 User Authentication
Authentication is the process of verifying whether a wireless device is allowed to use the wireless
network. You can make every user log in to the wireless network before using it. However, every device
in the wireless network has to support IEEE 802.1x to do this.
For wireless networks, you can store the user names and passwords for each user in a RADIUS server. This
is a server used in businesses more than in homes. If you do not have a RADIUS server, you cannot set up
user names and passwords for your users.
Unauthorized wireless devices can still see the information that is sent in the wireless network, even if they
cannot use the wireless network. Furthermore, there are ways for unauthorized wireless users to get a
valid user name and password. Then, they can use that user name and password to use the wireless
network.
7.9.3.4 Encryption
Wireless networks can use encryption to protect the information that is sent in the wireless network.
Encryption is like a secret code. If you do not know the secret code, you cannot understand the
message.
Many types of encryption use a key to protect the information in the wireless network. The longer the
key, the stronger the encryption. Every device in the wireless network must have the same key.
7.9.4 Signal Problems
Because wireless networks are radio networks, their signals are subject to limitations of distance,
interference and absorption.
Problems with distance occur when the two radios are too far apart. Problems with interference occur
when other radio waves interrupt the data signal. Interference may come from other radio
transmissions, such as military or air traffic control communications, or from machines that are
coincidental emitters such as electric motors or microwaves. Problems with absorption occur when
physical objects (such as thick walls) are between the two radios, muffling the signal.
7.9.5 BSS
A Basic Service Set (BSS) exists when all communications between wireless stations or between a wireless
station and a wired network client go through one access point (AP).
Intra-BSS traffic is traffic between wireless stations in the BSS. When Intra-BSS traffic blocking is disabled,
wireless station A and B can access the wired network and communicate with each other. When Intra-
BSS traffic blocking is enabled, wireless station A and B can still access the wired network but cannot
communicate with each other.
