Wireless networking - which is often just known as Wi-Fi - is a way of getting broadband internet without wires.

Wi-Fi allows you to connect several computers at once, anywhere in the house - or if you have a laptop, to even use your computer in the garden. You don’t need to install extra phone lines or cables.

How does it work?

Wi-Fi creates a network in your home or office – a little zone where computers can get broadband internet. It uses radio waves, just like TV or mobile phones. You may sometimes hear this zone referred to as a WLAN (Wireless Local Area Network).

A device called a wireless transmitter receives information from the internet via your broadband connection. The transmitter converts the information into a radio signal and sends it.

You could think of the transmitter as a mini radio station, broadcasting signals sent from the internet. The ‘audience’ for these transmissions is the computer (or computers, as more than one can connect at the same time) which receives the radio signal via something called a wireless adapter.

The whole process, meanwhile, works in reverse, with the computer sending information to the wireless transmitter. It then converts them and sends them via your broadband connection.

Many ISPs will supply you with a router, modem and wireless transmitter combined in one device, which it calls ‘the router’. To make your Wi-Fi set-up as simple as possible, you should consider using a similar device.

The router plugs directly into a phone socket and doesn’t need a computer to run it, so you don’t have to set up your computer next to the router.

Computers – mainly laptops – increasingly have built-in Wi-Fi receivers. If not, the simplest method of installing a receiver is a dongle - a little device that plugs into a USB port and transmits between your PC and wireless router.

Security risks

There are several risks involved in not properly securing a wireless network:

Data interception

By default, a wireless network is unsecured. This means that it is open to everyone, and anyone within the coverage area of an access point may potentially listen to communications being sent on the network. For an individual, there is little threat, as data is rarely confidential, unless the data is of a personal nature. For a business, however, this may pose a serious problem.

Network intrusion

When an access point is installed on a local network, it lets any station access the wired network, as well as the Internet, if the local network is connected to it. For this reason, an unsecured wireless network gives hackers the perfect gateway to an business or organization's internal network.

Besides letting the hacker steal or destroy information on the network and giving him or her free Internet access, the wireless network might also be helping him or her to carry out cyber-attacks. Indeed, since there is no way to identify a hacker on a network, the business which installed the wireless network might be held responsible for the attack.

Radio jamming

Radio waves are very sensitive to interference. This is why a signal can easily be jammed by a radio transmission with a frequency close to that used by the wireless network. Even a simple microwave oven can make a wireless network completely inoperable if it is being used within an access point's range. Some businesses secure their internal wireless network within a Faraday Cage - a form of metal cage which is hard for external hackers to penetrate or steal data.

Denial of service

The 802.11 standard's network access method is based on the CSMA/CA protocol, which involves waiting until the network is free before transmitting data frames. Once the connection is established, a station must be linked to an access point in order to send it packets. Because the methods for accessing a network and associating with it are known, it is easy for a hacker to send packets requesting for a station to become disassociated from the network. Sending out information intended to disrupt a wireless network is called a denial of service attack.

What's more, connecting to wireless networks uses up power. Even if the wireless peripheral devices have power-saving features, a hacker may be able to send enough encrypted data to a machine for it to overload. Many portable peripherals (like PDAs and laptop computers) have limited battery life. Therefore, a hacker may want to cause excessive power consumption that renders the device temporarily unusable, which is called a battery exhaustion attack.

Wireless Security

In wireless security, passwords are only half the battle. Choosing the proper level of encryption is just as vital, and the right choice will determine whether your wireless LAN is a house of straw or a shielded fortress.

Most wireless access points come with the ability to enable one of three wireless encryption standards: Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA) or WPA2. Explore the chart below to get a basic understanding of the differences between WPA, WEP and WPA2, as well as the uses and mechanisms of each one of these wireless security protocols, and to find out whether WPA, WEP or WPA2 is the best choice for your environment.

Wi-Fi Frequencies and channels

There are two frequency bands available to use when setting up a WiFi network. There are:

2.4 GHz is the most universally used frequency. The waves in this radio frequency are about 5 inches long and can pass through walls, windows and others objects reasonably well and the signals have a range up to about 100 metres. Because this frequency is the most common one, it can result in devices interfering with each other. When setting up a wireless network, 2.4 GHz is compatible with standards for building a wireless network known as 802.11b and 802.11g.

5 GHz is less common. It has a wavelength of about 2.5 inches long and that means it isn't quite as good at passing through walls, windows and other objects compared to using 2.4 GHz. It's range is about 30 metres. The result is that the range isn't as good, although sometimes, higher speeds can be achieved because it is a less crowded frequency. When setting up a wireless network, 5 GHz is compatible with standards for building a wireless network known as 802.11a and 802.11n and 802.11ac.

Channels in the 2.4 GHz frequency band

Each frequency band is divided up into 'channels. The 2.4 GHz band has 14 channels, as shown in the diagram below.

Athough there are 14 channels, not all of them may be available, depending upon which country you are in. In the UK, only channels 1 - 13 are available.

You can see from the diagram that, for example, channel 6 operates at 2.437 GHz whereas channel 11 operates at 2.462 GHz. Unfortunately, most of the channels overlap. This means that they can interfere with each other and because there are so few channels, a few of them might be used by many devices, causing overloading and a poor WiFi signal. Channels 1, 6 and 11 do not overlap so tend to be the preferred default channels to use first because these channels minimise interference from the other channels.

Channels in the 5 GHz frequency band

The 5 GHz band has 24 channels and all of them do not overlap with the other channels. When you set up a network, therefore, you have more channel options to select from to minimise interference, especially because 5 GHz frequency band is not so popular as 2.4 GHz.

Interference and signal direction

Radio waves can be bounced around by many things, including walls, mirrors, water and metal surfaces. Even the metal strands inside safety glass will break up radio signals! It's therefore important to think about not just the frequency and channel to use but also where to position the Wireless Access Points (WAPs) in a wireless network. In addition, the type of antenna used by the WAPs is important to note. Some are omnidirectional, which means the radio signals radiate out from the antenna in all directions uniformly. This can be an advantage in some wireless network designs because you know the signal is going to go out to all surrounding areas. Since the signal is going out in all directions, however, it gets weaker as the distance from the antenna increases. WAPs with directional antennas send out their wireless signals in a more focused direction. This means that they have to be adjusted properly, pointing in the right direction. As the signal isn't going out in all directions, however, it's stronger so can travel further.