You can then use the ifconfig command or perhaps a graphical Ubuntu
tool to set the device networking parameters, and the interface will work as on
a hardwired LAN. One handy output of the iwconfig command is the link
quality output, which you can use in shell scripts or other graphical utilities
for signal-monitoring purposes.
Choosing from Among Available Wireless Protocols
The Institute of Electrical and Electronics Engineers (IEEE) started to look
seriously at wireless networking in 1990. This is when the 802.11 standard
was first introduced by the Wireless Local Area Networks Standards Working
Group. The group based the standard roughly around the architecture used in
cellular phone networks. A wireless network is controlled by a base station,
which can be just a transmitter attached to the network or, more commonly
these days, a router.
A larger network may use more than one base station. Networks with more
than one base station are usually referred to as distribution systems. You can
use a distribution system to increase coverage area and support roaming of
wireless hosts. You can also use external omnidirectional antennas to increase
the coverage area or, if required, you can use point-to-point or directional
antennas to connect distant computers or networks.
The 802.11 standard specifies that wireless devices use a frequency range of
2400MHz to 2483.5MHz. This is the standard used in North America and
Europe. In Japan, however, wireless networks are limited to a frequency range
of 2471MHz to 2479MHz. Within these ranges, each network is given up to
79 nonoverlapping frequency channels to use. This reduces the chance of two
closely located wireless networks using the same channel at the same time. It
also allows for channel hopping, which can be used for security.
Beyond the Network and onto the Internet
Ubuntu supports Internet connections and the use of Internet resources in
many different ways. You will find a wealth of Internet-related software
included with this book’s version of Ubuntu, and you can download hundreds
of additional free utilities from a variety of sources. To use them, you must
have a working Internet connection.
In this section, you learn how to set up an Internet connection in Ubuntu
using a modem and Point-to-Point Protocol (PPP) as well as other
connection methods, including digital subscriber line (DSL) and cable