ZyXEL Communications P-660W-T1 v2, Руководство пользователя

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Chapter 6 Wireless LAN
P-660W-Tx v2 User’s Guide
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The SSID is the name of the wireless network. It stands for Service Set IDentifier.
• If two wireless networks overlap, they should use different channels.
Like radio stations or television channels, each wireless network uses a specific channel,
or frequency, to send and receive information.
• Every wireless client in the same wireless network must use security compatible with the
AP.
Security stops unauthorized devices from using the wireless network. It can also protect
the information that is sent in the wireless network.
Radio Channels
In the radio spectrum, there are certain frequency bands allocated for unlicensed, civilian use.
For the purposes of wireless networking, these bands are divided into numerous channels. This
allows a 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.
6.6.2 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 WPA-PSK security standard is
very secure if you use a long key which is difficult for an attacker’s software to guess - for
example, a twenty-letter long string of apparently random numbers and letters - but it is not
very secure if you use a short key which is very easy to guess - for example, a three-letter word
from the dictionary.
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.