ZyXEL Communications P-660N-T1A, Руководство пользователя

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Chapter 8 Wireless LAN
P-660N-T1A User’s Guide
119
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.
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 her favorite movie is Vanishing Point
(which you know was made in 1971) you could use “70dodchal71vanpoi” as your
security key.
The following sections introduce different types of wireless security you can set up
in the wireless network.
8.8.3.1 SSID
Normally, the ZyXEL Device acts like a beacon and regularly broadcasts the SSID
in the area. You can hide the SSID instead, in which case the ZyXEL Device does
not broadcast the SSID. In addition, you should change the default SSID to
something that is difficult to guess.
This type of security is fairly weak, however, because there are ways for
unauthorized wireless devices to get the SSID. In addition, unauthorized wireless
devices can still see the information that is sent in the wireless network.
8.8.3.2 MAC Address Filter
Every device that can use a wireless network has a unique identification number,
called a MAC address.
1
A MAC address is usually written using twelve hexadecimal
characters
2
; for example, 00A0C5000002 or 00:A0:C5:00:00:02. To get the MAC
address for each device in the wireless network, see the device’s User’s Guide or
other documentation.
1. Some wireless devices, such as scanners, can detect wireless networks but cannot use wireless networks.
These kinds of wireless devices might not have MAC addresses.
2. Hexadecimal characters are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F.