Dummies, Wireless

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Part III: Installing a Wireless Network
range, you should see the SSID on your computer’s network adapter client
software and be able to select it and connect to it — that is, assuming you
have the right WEP key, if WEP is configured on that access point. When
you create a closed network, you turn off this broadcast so that only
people who know the exact name of the access point can connect to it.
You can find access points even if they’re not broadcasting their SSIDs
(by observing other traffic on the network with a network sniffer program),
so this security measure is an imperfect one — and no substitute
for enabling WPA. But it’s another layer of security for your network.
Also, if you’re in a situation where you will have lots of people coming
into your home and wanting to share your connection, you may not
want to close off the network, so you’ll need to balance convenience for
your friends against the small exposure of a more open network.
� Set access control at the MAC layer: Every network adapter in the world
has assigned to it a unique number known as a Media Access Control
(MAC) address. You can find the MAC address of your network adapter
by looking at it (it’s usually physically printed on the device) or using
software on your computer:
• Open a DOS window and use the winipcfg command in Windows
95, 98, or Me or the ipconfig/all command in Windows NT,
2000, or XP.
• Look in the Network Control Panel or System Preference on
a Mac.
Dealing with the WEP hex and ASCII issues
One area that is consistently confusing when
setting up a WEP key — and often a real pain —
is the tendency of different vendors to use different
formats for the keys. The most common
way to format a key is to use hexadecimal (hex)
characters. This format represents numbers and
letters by using combinations of the numbers 0–9
and the letters A–F. (For example, the name of
Pat’s dog, Opie, would be represented in hexadecimal
as 4f 70 69 65.) A few other vendors use
ASCII, which is simply the letters and numbers
on your keyboard.
Although ASCII is an easier-to-understand
system for entering WEP codes (it’s really just
plain text), most systems make you use hexadecimal
because it’s the standard. The easiest
way to enter hex keys on your computers connecting
to your access point is to use the
passphrase we discuss in the section “Enabling
encryption.” If your network adapter client software
lets you do this, do it! If it doesn’t, try entering
the WEP key you wrote down when you
generated it (it’s probably hexadecimal). If that
doesn’t work either, you may have to dig into the
user’s manual and see whether you need to add
any special codes before or after the WEP key to
make it work. Some software requires you to put
the WEP key inside quotation marks; other software
may require you to put an 0h or 0x (that’s a
zero and an h or an x character) before the key or
an h after it (both without quotation marks).