Sybex CEH Certified Ethical Hacker Version 8 Study Guide

What Is a Wireless Network? 351
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Some of the advantages are as follows:
You have the convenience of not having to deal with wires.
You can be connected in places where it would be impossible to run wires.
The Fine Print
A wireless network uses radio waves to transmit data. The technical details that define a
wireless network and 802.11 occur at the physical layer of the network. The standard that
defines Wi-Fi was itself built from the 802.11 specification. The Wi-Fi standard defines
many details, including how to manage a connection through techniques such as directsequence
spread spectrum (DSSS), frequency-hopping spread spectrum (FHSS), infrared
(IR), and orthogonal frequency-division multiplexing (OFDM).
In this chapter we will be talking about four environments built around the technology
and how each varies. These are:
■ Extension to an existing wired network as either a hardware- or software-based
access point
■ Multiple access points
■ LAN-to-LAN wireless network
■ 3G or 4G hot spot
The first type, which uses access points, comes in one of two types: hardware- or
software-based. Hardware-based access points (HAPs) use a device such as a wireless
router or dedicated wireless access point for Wi-Fi–enabled clients to attach to as needed.
A software-based access point (SAP) is also possible through the use of a wireless-enabled
system attached to a wired network, which, in essence, shares its wireless adapter.
The second type involves providing more than one access point for clients to attach to as
needed. With this implementation, each access point must have some degree of overlap with
its neighboring access points. When it has been set up correctly, this network allows clients
to roam from location to location seamlessly without losing connectivity.
A LAN-to-LAN wireless network, the third type, allows wired networks in different
locations to be connected through wireless technology. This approach has the advantage of
allowing connection between locations that may otherwise have to use a more expensive
connectivity solution.
A 3G/4G hot spot, the fourth type, provides Wi-Fi access to Wi-Fi–enabled devices,
including MP3 players, notebooks, cameras, PDAs, netbooks, and more.
The 3G/4G hot spot has become very popular in recent years as smartphones
and other devices all have provided this type of feature as a standard item.
Wireless Standards in Use
Not all wireless standards are the same, and you should become familiar with the
differences and similarities of each (see Table 15.1).