Wireless Networks

Wireless Overview

Wireless network access is prominent everywhere today. WiFi, local area networks are available in most coffee shops, hotels, small and large businesses, educational institutions and the typical home network as well. The trend toward wireless networking started well before the current explosion of portable wireless devices like smart phones, tablets, and e-readers. The popularity of wireless local area networks comes from the fact that wireless ethernet offers flexibility, the ability to connect from anywhere there is a wireless signal versus being tethered to a cable; scalability, in that additional wireless users do not require additional networking hardware like switches and cables; and affordability in that radio waves are cheaper than running ethernet cables. Wireless networking has also benefited from agreed upon industry standards and advances in wireless bandwidth speeds. One of the challenges to wireless local area networks has been maintaining a high level of network and data security, which has proved to be difficult with a medium that travels across open air waves. Today there is a variety of methods in securing and encrypting wireless networks.

Wireless Standards

The ITU, IEEE and the WiFi Alliance are organizations that promote worldwide wireless standards which help vendors manufacture wireless devices that are interoperable with one another. In the chart below, you can see that the IEEE 802.11b, g, and n standards all operate at the 2.4 Ghz frequency range and as a result of the organizations listed above, the IEEE 802.11b, g, and n standards are all backwards compatible with one another. This allows the possibility of a laptop with an 802.11g wireless network card to work on an 802.11n wireless network, and so on.


IEEE Standards Radio Frequency Bandwidth Speed Signal Distance
802.11a 5 Ghz Up to 54 Mbps under 150 ft or 35 m
802.11b 2.4 Ghz Up to 11 Mbps under 150 ft or 35 m
802.11g 2.4 Ghz Up to 54 Mbps under 150 ft or 35 m
802.11n 2.4 Ghz Up to 200+ Mbps under 300 ft or 70 m

 

The chart above points to some obvious advantages and disadvantages, like bandwidth speeds, between the different wireless technologies. But what about the differences between 802.11.a and 802.11g? They both use OFDM modulation techniques to achieve speeds up to 54 Mbps. So what is the difference between the 5Ghz (802.11a) and 2.4 Ghz (802.11bgn) radio frequencies? When 802.11a was developed the idea of moving wireless devices away from the the 2.4 Ghz frequency was considered a benefit. Many wireless devices at that time, like wireless phones used the same 2.4 Ghz frequency range which caused interference.

The Wireless Network

The wireless network requires a wireless networking device for clients to connect to like a switch without the ethernet cables, a wireless access point is a wireless networking device that connects clients to the network wirelessly. A wireless router is a powerful networking device, in that it combines the abilities of a wireless access point and a router, into one networking device capable of routing, DHCP services, NAT services, and more. Many home networks have wireless routers, that when improperly configured, and not secured, can become a network security risk.

A wireless client is a device with a wireless network interface card (NIC) configured to connect to the wireless access point or wireless router. The client can be a portable device like a tablet, PDA, laptop or phone, or it can be a stationary device like a desktop computer with a wireless NIC installed.

SSID – The SSID or service set identifier is the name identifier of the wireless network, and it is used to connect to that wireless network.  The wireless access point or router can broadcast the SSID and wireless clients in range of the WAP/router will see the wireless network identified by the SSID and can then attempt to connect to that wireless network. Network administrators can choose to not broadcast the SSID and in that case wireless clients within range of the WAP/router will be able to see detect that there is a wireless device, but will not know the SSID. Many people mistakenly see this as a form of wireless network security preventing clients from connecting to the wireless network. While it is true that the SSID is needed to connect to the network, it is an easy process for a hacker to use available software tools to discover the hidden SSID.

Video Tutorials

 In part1, I discuss the wireless network topology and connecting to a Linksys wireless router’s default settings 

In part 2, I configure the Linksys router’s internet and wireless interfaces IP as well as the DHCP server scope, and SSID

In part 3, I configure the router’s wireless security settings and WPA2 encryption

Author: Dan

Dan teaches computer networking and security classes at Central Oregon Community College.

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