Chapter 7 Wireless
EX5501-B0 / AX7501-B0 / PX7501-B0 User’s Guide
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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.
7.9.3.1 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.
7.9.3.2 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 Zyxel 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.
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.
