ZyXEL Communications VMG4381-B10A, Руководство пользователя

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Chapter 7 Wireless
VMG4381-B10A User’s Guide
122
wireless users to get a valid user name and password. Then, they can use that user name and
password to use the wireless network.
7.10.3.4 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.
The types of encryption you can choose depend on the type of authentication. (See Section
7.10.3.3 on page 121 for information about this.)
For example, if the wireless network has a RADIUS server, you can choose WPA or WPA2. If users
do not log in to the wireless network, you can choose no encryption, Static WEP, WPA-PSK, or
WPA2-PSK.
Usually, you should set up the strongest encryption that every device in the wireless network
supports. For example, suppose you have a wireless network with the Device and you do not have
a RADIUS server. Therefore, there is no authentication. Suppose the wireless network has two
devices. Device A only supports WEP, and device B supports WEP and WPA. Therefore, you should
set up Static WEP in the wireless network.
Note: It is recommended that wireless networks use WPA-PSK, WPA, or stronger
encryption. The other types of encryption are better than none at all, but it is still
possible for unauthorized wireless devices to figure out the original information
pretty quickly.
When you select WPA2 or WPA2-PSK in your Device, you can also select an option (WPA
compatible) to support WPA as well. In this case, if some of the devices support WPA and some
support WPA2, you should set up WPA2-PSK or WPA2 (depending on the type of wireless network
login) and select the WPA compatible option in the Device.
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.
7.10.4 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
Table 30
Types of Encryption for Each Type of Authentication
NO AUTHENTICATION RADIUS SERVER
Weakest No Security WPA
Static WEP
WPA-PSK
Strongest WPA2-PSK WPA2