An Introduction to Wireless Networking (Part 1) - 802.11 Overview
ITSY 2417 – Wireless Security Development
Prof. Michael P. Harris, CCNA, CCAI
Introduction
Whether it’s because you have made a call using a mobile phone, received a message
on your pager, checked your email from a PDA or even just seen an advert related to
it, we have all come across a wireless data or voice network!
If a user, application or company wishes to make data portable, mobile and accessible
then wireless networking is the answer. A wireless networking system would rid of the
downtime you would normally have in a wired network due to cable problems. It
would also save time and money due to the fact that you would spare the expense of
installing a lot of cables. Also, if a client computer needs to relocate to another part
of the office then all you need to do is move the machine with the WNIC (Wireless
Network Card).
Wireless networking can prove to be very useful in public places – libraries, guest
houses, hotels, cafeterias, and schools are all places where one might find wireless
access to the Internet. From a financial point of view, this is beneficial to both the
provider and the client. The provider would offer the service for a charge – probably
on a pay per use system, and the client would be able to take advantage of this
service in a convenient location; away from the office or home. A drawback of
wireless Internet is that the QoS (Quality of Service) is not guaranteed and if there is
any interference with the link then the connection may be dropped.
Types of Wireless Networks
WLANS: Wireless Local Area Networks
WLANS allow users in a local area, such as a university campus or library, to form a
network or gain access to the internet. A temporary network can be formed by a
small number of users without the need of an access point (AP) / wireless access
point (WAP); given that they do not need access to network resources.
WPANS: Wireless Personal Area Networks
The two current technologies for wireless personal area networks are Infra Red (IR)
and Bluetooth (IEEE 802.15). These will allow the connectivity of personal devices
within an area of about 30 feet. However, IR requires a direct line of site and the
range is less.
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WMANS: Wireless Metropolitan Area Networks
This technology allows the connection of multiple networks in a metropolitan area
such as different buildings in a city, which can be an alternative or backup to laying
copper or fiber cabling.
WWANS: Wireless Wide Area Networks
These types of networks can be maintained over large areas, such as cities or
countries, via multiple satellite systems or antenna sites looked after by an ISP. These
types of systems are referred to as 2G, 3G, and 4G (2nd Generation etc.) systems.
Below is a table indicating the range that wireless data networks can handle:
Meters
0-10
0-100
0-10000
Network
Personal Area Network
Local Area Network
Wide Area Network
Security
The following are three methods of security available when it comes to wireless:
WEP (Wired Equivalent Privacy)
Wired Equivalent Privacy is intended to stop the interception of radio frequency
signals by unauthorized users and is most suitable for small networks. This is so
because there is no key management protocol and each key must be entered manually
into the clients – this proves to be a very time consuming administrative task. WEP is
based on the RC4 encryption algorithm by RSA Data Systems. It works by having all
clients and Access Points configured with the same key for encryption and decryption.
SSID (Service Set Identifier)
SSID acts a simple password or workgroup name by allowing a WLAN network to be
split up into different networks each having a unique identifier. These identifiers will
be programmed into multiple access points. To access any of the networks, a client
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computer must be configured with a corresponding SSID for that network. If they
match then access will be granted to the client computer.
MAC (Media Access Control) address filtering
A list of MAC addresses belonging to the client computers can be inputted into an
Access Point and thus only those computers will be allowed access. When a computer
makes a request, its MAC address is compared to that of the MAC address list on the
Access Point and permission granted or denied. This is a good method of security but
only recommended for smaller networks as there is a high rate of work involved in
entering each MAC address into every Access Point.
Understanding the 802.11 family
The 802.11 standard first appeared in the 1990’s and was developed by the Institute
of Electrical and Electronics Engineers. It has now emerged and expanded to be one
of the leading technologies in the wireless world.
802.11
Using either FHSS (frequency hopping spread spectrum) or DSSS (direct sequence
spread spectrum) this provides a 1 to 2 Mbps transmission rate on the 2.4GHz band.
802.11a
Using the OFDM (orthogonal frequency division multiplexing) this provides up to
54Mbps and runs on the 5GHz band.
802.11b
Also known as Wi-Fi or High Rate 802.11, uses DSSS and applies to wireless LANs. It is
most commonly used for private use, at home. It provides an 11 Mbps transmission
rate and has a fallback rate of 5.5, 2 and 1 Mbps.
802.11g
This provides a 20+ Mbps transmission rate, applies to LANs and runs on the 2.4GHz
band.
The image below demonstrates the wireless data infrastructure as an extension of the
Internet.
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Bluetooth
Bluetooth is a simple type of wireless networking that allows the formation of a small
network with up to eight devices being connected at once. Such devices would
include PDAs, Laptops, Mobile Phones and Personal Computers. However, Bluetooth
may also be found in keyboards, mice, headsets and mobile phone hands-free kits,
amongst others. It was originally invented by Ericsson in 1994. In 1998 the Bluetooth
SIG (Special Interest Group) was formed by a small number of major companies –
Ericsson, Nokia, Intel and Toshiba – to help each other develop and promote the
technology. Bluetooth falls under personal area networking (PAN) since it is has a
very short range – 30 to 300 feet. This sort of range adds to the security of such a
technology in that if someone wanted to sniff your connection they would not only
need special equipment but they would have to be fairly close to you. The main
features of Bluetooth are that unlike Infra Red, the signal is not affected by walls it
uses radio technology, it is not very expensive, and has little power consumption.
This concludes part one of my three part Introduction to Wireless Networking Lesson.
In part two we’ll look at what is needed, how to setup a wireless network and what
Windows Server 2003/2008 has to offer when it comes to wireless networking.
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An Introduction to Wireless Networking (Part 2) - Requirements and Setup
An Introduction to Wireless Networking (Part 3) - Security, General Tips and Tricks
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