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Introduction to Wireless Security

written by: Matthew Casperson•edited by: Brian Nelson•updated: 9/12/2008

Wireless networks are convenient and popular, but without security are easy to hack and leave your data at risk. This article gives a brief overview of the most popular forms of wireless security for home networks.

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    I received a call from a customer the other day. She had recently moved from dial-up to an entry level broadband account, and had set up a wireless router so she could move her laptop around her unit. Initially everything had been great, but over the last few weeks her internet had slowed down to the point where it was worse than her old dial-up account. When I took a look at her router I discovered that it had no wireless security, and 2 additional wireless clients attached. Over the course of a few minutes we watched as the wireless freeloaders downloaded hundreds of megabytes of data.

    Hacking a computer network has been the plot of many a Hollywood movie, but the truth is that most wireless routers do not enable wireless security by default, and “hacking” an unsecured wireless network is as simple as viewing a list of available wireless networks in Windows and double clicking on any network that is unsecured. Not only does this make stealing bandwidth trivial, but if you have file sharing enabled you could find your personal photos, financial records or emails freely visible to anyone with a laptop within a few hundred feet.

    The good news is that protecting your wireless network is not difficult, and there are a number of well supported standards that allow you to limit access to your wireless network.

    Wired Equivalent Privacy, or WEP, was introduced in 1999. Its goal was to provide a wireless network with the same security inherent to the traditional wired networks. In a typical scenario implementing WEP is as simple as creating a key (which is basically a password) of 10 or 26 hexadecimal (i.e. between 0 and 9, A and F) characters which is saved in the router, and then used by any wireless client wanting to connect to it. An example WEP key is 74534b7126.

    However since its introduction a number of flaws have been discovered in WEP. The obscure nature of the WEP key may give WEP a false sense of security, but from a cryptographic standpoint it is a relatively easy system to break. A quick web search on “WEP cracking” will yield detailed instructions on how to crack a WEP wireless network in minutes using mainstream and freely available hardware and software.

    The vulnerabilities inherent in WEP prompted the creation of Wi-Fi Protected Access (WPA) in 2003. WPA addresses WEP's insecurity, and is usually supported in older devices by way of a firmware update. In a typical scenario implementing WPA involves creating a key of between 8 and 63 characters. Just like WEP, this key is saved in the router and then used by any wireless client wanting to connect to it. But unlike WEP the WPA key is usually an ASCII string like pa55w0rd, which is much easier to remember. This form of WPA is known as WPA Pre-Shared Key (WPA-PSK). It is the most common usage of WPA in small networks and home networks. WPA Enterprise allows authentication against a RADIUS server, however the added complexity of having a dedicated server hosting user credentials restricts the usage of WPA Enterprise to larger networks.

    WPA2 is the successor to WPA, and since 2006 support for WPA2 has been mandatory for all "Wi-Fi CERTIFIED" devices. WPA2 offers increased security over WPA, but its relatively recent introduction means that not all wireless devices support it.

    Given how easy it is to connect to an unsecured wireless network it is imperative that you implement some form wireless security. In a home or small business environment WPA is just as easy to set up as WEP and provides better security. Should your network hardware support it, WPA2 offers even better security.

    Despite eventually setting up security on her wireless network, the story for my customer didn't end well. Her entry level broadband account included additional charges for any usage over her modest limit. Not having a secured wireless network landed her a hefty bill from her ISP. It was a costly mistake, and one that is easily avoided.