Planning Security

Any network can be attacked by a persistent hacker, but a well-defended network
discourages most hackers sufficiently to keep your data safe. However,
it’s easier for a hacker to gain access through the air to a wireless network
than to gain physical access to a wired network, making wireless networks,
and even home networks, more vulnerable to attack. Because a Wi-Fi signal
is a radio signal, it keeps going and going and going, like ripples in a pond,
in a weaker and weaker form until it hits something solid enough to stop it.
Anyone with a portable PC, wireless network adapter, and an external antenna
in a van driving by your house, or even a neighbor with this equipment, has a
reasonable chance of accessing your wireless network. (Such skullduggery is
known as war driving.) So, you must plan for security. We give you all the
down-and-dirty details in Chapter 9, but here are some key things to keep
in mind:

Internet security: Any Internet connection — especially always-on broadband
connections, but dial-up connections, too — can be vulnerable to
attacks arriving from the Internet. To keep your PCs safe from the bad
folks (who may be thousands of miles away), you should turn on any firewall
features available in your AP or router. Some fancier APs or routers
include a highly effective kind of firewall (a stateful packet inspection [SPI]
firewall), but even just the basic firewall provided by any NAT router can
be quite effective. You should also consider installing antivirus software
as well as personal firewall software on each PC or Mac on your network
for an extra level of protection.
Airlink security: This is a special need of a wireless home network. Wired
networks can be made secure by what’s known as physical security. That
is, you literally lock your doors and windows, and no one can plug into
your wired network. In the wireless world, physical security is impossible
(you can’t wrangle those radio waves and keep them in the house), so
you need to implement airlink security. You can’t keep the radio waves
from getting out of the house, but you can make it hard for someone to
do anything with them (like read the data they contain). Similarly, you
can use airlink security to keep others from getting onto your access
point and freeloading on your Internet connection. The primary means
of providing airlink security — and advances are on the way — is called
WPA2 (Wi-Fi Protected Access). You absolutely should use WPA2