Windows XP Hacks [Electronic resources] نسخه متنی

Hack 42 War Driving for WiFi Access

WiFi networks are everywhere, it seems; you can
get free Internet access on wireless community FreeNets armed with
your laptop, a car, and software called Network Stumbler.

One of the coolest technological advances
in popular use today is the wireless network. Wireless networks based
on the
WiFi standard
(802.11x) are becoming increasingly common
across the countrynot only in people's homes,
but also in universities, corporations, coffee shops, airports and
other public places. Now you can bring your email to Starbucks.

There are frequently dozens near one another, particularly in certain
urban neighborhoods and suburban office parks that house high-tech
companies. Where I livein Porter Square in Cambridge,
Massachusettsthere are dozens of wireless networks in private
homes, apartment buildings, and businesses within a very short walk
from my home. There are at least half-a-dozen on my three-block
street alone, in addition to mine. From my back porch, I get access
to my own wireless network, but can also often pick up signals from
four nearby WiFi networks.

The widespread availability of these
inexpensive WiFi networks has led to a grassroots community wireless
networking movement. The idea is simple: allow people passing by to
use your WiFi network to hop onto the Internet and they in turn let
you and others use their WiFi networks for Internet access when you
pass near their homes or places of business. These wireless
grassroots organizations are often called FreeNets.
You'll find them in cities including New York,
Seattle, Houston, and the San Francisco Bay area, as well as others.
For more details about them and how to participate, go to Free
Networks.org (http://www.freenetworks.org) In fact, some
cities themselves are creating free wireless zones in downtown
business areas to allow anyone with a wireless-enabled computer to
get Internet access. Paris, for example, may soon be known for more
than its beauty, culture, good food and disdain for tourists; it may
turn into one giant wireless zone, allowing Internet access anywhere
in the city, though for a price.

How do you find these wireless networks? The best way is by doing
what has become known as war
drivingdriving through neighborhoods with your
laptop, special software, and, if you want to pick up more networks,
an antenna hooked up to your WiFi card.

The extremely environmentally conscious prefer to go war walking, though walking around with a laptop is not particularly easy. A better way is with a WiFi-equipped PDA, like the Palm Tungsten C.

Run the software, and it not only locates the network, but also
provides a variety of information about it that you can use to
connect to it, such as its SSID (network name), whether it uses
encryption, and the wireless channel it's on. Armed
with that information, you should be able to connect to it if
it's a FreeNetfor example, if it is set to
allow anyone to connect to it, or if it uses a commonly agreed-upon
security scheme that everyone in the FreeNet uses for their WiFi
networks.

If you walk in certain urban neighborhoods, you may notice strange symbols on the sidewalk that look something like those pictured in Figure 5-1. Yes, it's a conspiracy, but in the positive sense. These are war chalking symbols that tell passersby that there is a nearby WiFi network. The left symbol means the wireless network is open; the middle one means it is closed; and the right one means it uses WEP encryption. There may be other information next to the symbol that gives information on how to connect to the network, such as the SSID. The symbols were inspired by the practice of hoboes, who during the Great Depression would make chalk marks near homes that were friendly to hoboes and would give them food. For more information about war chalking, go to http://www.warchalking.org.

Figure 5-1. War chalking symbols

To go war driving, download the free Network
Stumbler program (http://www.netstumbler.com), which shows you
detailed information about any nearby wireless network. Figure 5-2 shows what happens when I run the software on
my back porch. I can detect signals from four nearby WiFi networks in
addition to my own.

Figure 5-2. Detecting nearby wireless networks with Network Stumbler

For each WiFi network it uncovers, Network Stumbler tells you the
network's SSID, name, manufacturer, channel, type,
signal strength, signal-to-noise ratio, and whether the
network's encryption is enabled, among other
details. Armed with that information, you can try to connect to the
network.

If a network uses encryption, a small lock appears next to it; look closely at the Mookieville network in Figure 5-2 and you might be able to see it.

Once you've found a network, exit Network Stumbler.
Then, to connect to the network, double-click on the small network
icon in the System Tray (officially known as the XP
Notification
Areathe area of the Taskbar where XP corrals little icons).
The Wireless Network Connection Status screen
appears. (To see what it looks like, flip ahead to Figure 5-26.) From this screen, choose Properties
Wireless Networks, and you'll see the
screen shown in Figure 5-3.

Figure 5-3. The Wireless Network Connection Properties screen

If this screen doesn't show you the network
uncovered by Network Stumbler, click Refresh. If the network still
doesn't show up, that's because the
signal is too weak for you to connect to it. To connect to a network
shown on this screen, click Configure and fill out the information
required in the screen. You'll then get into the
network.

Not everyone will be able to use Network Stumbler, because it
won't work with all wireless network cards. As of
this writing, it worked with the following cards (and possibly some
others not listed here as well): Lucent Technologies WaveLAN/IEEE
(Agere ORiNOCO); Dell TrueMobile 1150 Series (PCMCIA and mini-PCI);
Avaya Wireless PC Card; Toshiba Wireless LAN Card (PCMCIA and
built-in); Compaq WL110; Cabletron/Enterasys Roamabout; Elsa
Airlancer MC-11; ARtem ComCard 11Mbps; IBM High Rate Wireless LAN PC
Card; and 1stWave 1ST-PC-DSS11IS, DSS11IG, DSS11ES, and DSS11EG. For
more information, go to C:\Program Files\Network
Stumbler\readmel, assuming you've
installed the program in C:\Program Files\Network
Stumbler.

Network Stumbler will find all wireless
networks near you, not just those that are part of FreeNets. So, you
may well find the wireless networks of people who
don't realize that others outside of their homes or
businesses can tap into their network. Some law enforcement officials
will tell you that tapping into those people's
networks is illegal, so be forewarned.

5.2.1 Mapping Wireless Networks

Network Stumbler lets you save your
war-driving information in a file, and you can then upload that
information to a web site (such as http://wifimaps.com) that uses your
information and information provided by many other war-drivers to
create maps of WiFi networks across the country. You can zoom in and
out on these maps, so you can get a view of the concentration of WiFi
networks in a metropolitan area, or you can see individual WiFi
networks on individual streets, as shown in Figure 5-4.

Figure 5-4. A map showing WiFi networks in my Somerville neighborhood

Go to http://wifimaps.com to view
the maps or to upload your Network Stumbler information. Be aware
that the site is a volunteer effort, and, not uncommonly,
you'll find that the maps aren't
working. If that happens, check back again in a few days; it usually
gets up and running after a while.

5.2.2 Build a Homemade Wireless Cantenna for War Driving

One way to increase the range of your war
driving and the strength of the signal when you connect to WiFi
networks is to build your own wireless antenna. You can build them
for a few dollars using a tin can and other stray parts, as long as
you're willing to do a little bit of soldering.
Because they're built out of tin cans,
they're frequently called
cantennas.

My 13-year-old son Gabe built several for his seventh-grade science
fair project and compared the effectiveness of each. The results were
clear: the giant 34.5-ounce coffee cans were far superior to
normal-sized coffee cans and Pringle's cans.

If you haven't bought a WiFi card yet and are
considering building one of these cantennas, I suggest buying an
Orinoco card. It has a small
connector in its side through which
you connect a pigtail
connector
, which can then be
hooked up to a small antenna you build out of copper wire and a small
connector, which goes inside the tin can. There are a number of
places you can buy a pigtail and the required connectors, including
Hyperlink Technologies (http://www.hyperlinktech.com). If you
don't have a WiFi card with a small connector,
building one of these cantennas becomes much more difficult.

There are many places online where
you can find good directions for making cantennas. Three good places
to start are www.oreillynet.com/cs/weblog/view/wlg/448,
www.netscum.com/~clapp/wirelessl, and
www.turnpoint.net/wireless/cantennahowtol.
Just so you get the idea of what you'll do, though,
you first empty and wash the can. Next, you build the small antenna
that will go inside the coffee can by soldering a short piece of
thick copper wire to a small piece of hardware called an N
connector. Then, drill a hole in the can and insert the
small antenna you just soldered. Attach the antenna to the can by
securing it with small screws and bolts. Attach one end of the
pigtail to your wireless card, attach the other end to the N
connector, and voila! You have a cantenna.

5.2.3 See Also

[Hack #57]

[Hack #53]