Chapter 7 Wireless LAN
variety of networks to exist in the same place without interfering with one another. When you create a network, you must select a channel to use.
Since the available unlicensed spectrum varies from one country to another, the number of available channels also varies.
7.10.2 Additional Wireless Terms
The following table describes some wireless network terms and acronyms used in the
Table 29 Additional Wireless Terms
TERM | DESCRIPTION |
Preamble | A preamble affects the timing in your wireless network. There are two preamble |
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Authentication | The process of verifying whether a wireless device is allowed to use the wireless |
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Fragmentation | A small fragmentation threshold is recommended for busy networks, while a larger |
Threshold | threshold provides faster performance if the network is not very busy. |
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7.10.3 Wireless Security Overview
By their nature, radio communications are simple to intercept. For wireless data networks, this means that anyone within range of a wireless network without security can not only read the data passing over the airwaves, but also join the network. Once an unauthorized person has access to the network, he or she can steal information or introduce malware (malicious software) intended to compromise the network. For these reasons, a variety of security systems have been developed to ensure that only authorized people can use a wireless data network, or understand the data carried on it.
These security standards do two things. First, they authenticate. This means that only people presenting the right credentials (often a username and password, or a “key” phrase) can access the network. Second, they encrypt. This means that the information sent over the air is encoded. Only people with the code key can understand the information, and only people who have been authenticated are given the code key.
These security standards vary in effectiveness. Some can be broken, such as the old Wired Equivalent Protocol (WEP). Using WEP is better than using no security at all, but it will not keep a determined attacker out. Other security standards are secure in themselves but can be broken if a user does not use them properly. For example, the
Because of the damage that can be done by a malicious attacker, it’s not just people who have sensitive information on their network who should use security. Everybody who uses any wireless network should ensure that effective security is in place.
A good way to come up with effective security keys, passwords and so on is to use obscure information that you personally will easily remember, and to enter it in a way that appears random and does not include real words. For example, if your mother owns a 1970 Dodge Challenger and
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