The following are the items most often at risk.

* Thieves can steal your sensitive personal and business data.

* Harmful viruses and worms can infiltrate your network, even evading your anti-virus software.

* Hackers can hijack your Wi-Fi to spam or attack others - and you could be liable.

If you don't want your network to fall victim to snooping or people 'borrowing' your bandwidth, then you're going to need to lock down your network. Luckily for you, all wireless technology has encryption built in -- it's just a matter of turning it on.

WEP Vs. WPA.

Security on wireless networks does have a flaw, though -- there are two completely incompatible standards, which makes it a pain to set up a whole network to use encryption.

How did this happen? Well, WEP (Wired Equivalent Privacy) was the original standard for encryption over 802.11 wireless networks. Back in 2001, though, a research paper was published called 'Weaknesses in the Key Scheduling Algorithm of RC4'. This paper demonstrated critical flaws in the security of WEP that made it trivial for someone to break into, if they wanted to.

Essentially, it is too easy to discover the secret 'key' used for WEP, and once you have the key, you can get into the network and stay in for as long as you want. People quickly recognised that it was almost useless to use WEP on their network -- but by the time its weaknesses were discovered, the WEP method was built into almost every piece of wireless equipment out there.

The WEP standard had to be replaced, and in 2003 WPA (Wi-Fi Protected Access) was introduced as its replacement, fixing most of its flaws. WPA is much more secure than WEP. Unfortunately, though, WPA took a long time to reach the market, and WPA devices were expensive when they were released. Combine this with the fact that WEP is still the default in a lot of software (because it's supported by more devices), and you end up in the confused situation we're in today.

Always Use WPA

If you're going to enable encryption, always use WPA. Devices bought after 2003 or so should be compatible with it, as the upgrade was made a mandatory part of the standard.

It is true that WEP is better than nothing -- it will, at least, deter the casual intruder, who won't try any more than double-clicking to get onto your network. WEP can also make you less of a target for wardrivers, since there will be so many completely open networks that they might as well use instead. However, it's silly to use WE nowadays when WPA is so easily available.

Turning on Encryption

Turning on encryption in Windows isn't too difficult, but it does involve quite a lot of clicking -- no wonder so few people bother.

The first step is to turn on encryption for your wireless router or access point. The exact method for this will vary between devices, but you can usually do it by visiting the router or access point's configuration page in your web browser, finding the encryption settings, and then choosing WPA. If you have any trouble, refer to your manual.

Once you've done that, you need to change the encryption settings on your computers. Open the 'View Available Wireless Networks' screen by right-clicking on your wireless connection in the bottom-right of the screen and choosing it from the menu that appears. Then click 'Change advanced settings'. Go to the Wireless Networks section of this box, click your network's name, and then click Properties.

Now, where it says 'Network authentication', select WPA. Click OK on everything you've opened. Once you've done that -- this is the really fun part -- you're going to have to do it for every computer on your network!

It's Easier for New Networks

While the process is quite troublesome for existing networks, it's much easier for ones that haven't been set up yet. You'll still need to turn on encryption at the wireless router or access point, but once you've done that you can set up encryption as you set up the network using the Wireless Network Setup Wizard.

Unfortunately (and stupidly) Windows now turns on WEP by default when you set up your wireless network. This means that each time you go through the wizard, you need to remember to tick the box on the third screen that says 'Use WPA encryption instead of WEP'. Still, it's easier than changing the settings manually later on.