ZyXEL Communications VMG1312-B10C, Руководство пользователя

Страница: 89 / 294

Chapter 6 Wireless
VMG1312-B10C User’s Guide
89
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.
6.10.3.1 SSID
Normally, the Device acts like a beacon and regularly broadcasts the SSID in the area. You can hide
the SSID instead, in which case the 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.
6.10.3.2 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.
You can use the MAC address filter to tell the Device which devices are allowed or not allowed to
use the wireless network. If a device is allowed to use the wireless network, it still has to have the
correct information (SSID, channel, and security). If a device is not allowed to use the wireless
network, it does not matter if it has the correct information.
This type of security does not protect the information that is sent in the wireless network.
Furthermore, there are ways for unauthorized wireless devices to get the MAC address of an
authorized device. Then, they can use that MAC address to use the wireless network.
6.10.3.3 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.
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.