ZyXEL N4100 Guia Do Utilizador
Chapter 25 Wireless LAN
N4100 User’s Guide
191
understand the information, and only people who have been authenticated are
given the code key.
given the code key.
These security standards vary in effectiveness. Some can be broken, such as the
old Wired Equivalent Privacy (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 perfectly 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.
old Wired Equivalent Privacy (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 perfectly 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.
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.
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.
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.
Signal Problems
Because wireless networks are radio networks, their signals are subject to
limitations of distance, interference and absorption.
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 coincidental emitters such as electric
motors or microwaves. Problems with absorption occur when physical objects
(such as thick walls) are between the two radios, muffling the signal.
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 coincidental emitters such as electric
motors or microwaves. Problems with absorption occur when physical objects
(such as thick walls) are between the two radios, muffling the signal.
25.3 Before You Begin
Before you start using these screens, ask yourself the following questions. See
if some of the terms used here do not make sense to
you.
• What wireless standards do the other wireless devices support (IEEE 802.11g,
for example)? What is the most appropriate standard to use?