How can I stay secure using Wi-Fi?

Wireless networking (or ‘Wi-Fi’) has a range of between 50 and 100 metres and is 'open access' - anyone's computer can connect to any wireless router. This poses two major problems.

Firstly, someone with a laptop living next door or in the same street can read your network traffic - all the web pages you visit, your user names and passwords and your online banking details.

Secondly, if someone nearby connects to your wireless router and downloads music illegally, not only will they use up your bandwidth allowance, but you might get a stiff letter from a lawyer as your internet address (your IP address) would be identified as the culprit.

You can protect yourself by changing the default settings on your wireless router and computer. You should have received a CD with your router – this will contain a program that allows you to adjust its settings, and there's plenty of information on the web about how to change the wireless settings under different versions of Windows.

But anyway, you should consider doing the following:

1. Change the router administration password

   Your wireless router has a password that restricts access to its settings, but each brand of router normally uses a well-known default password. You should change this to a strong password of your own. This can help prevent an outsider reconfiguring your router maliciously via the network.

2. Change the network SSID

   The SSID is the name of your network. Every device on your network must be set to the same SSID so they know they're part of the same network. The SSID can be up to 32 characters long and may contain any symbols you can type at the keyboard. As you don't have to remember it from day to day, it can be as long and complex as you like. It should not be obvious to an outsider so avoid words and names.

   By default your computer will probably obtain the SSID from your router automatically, but for good security it must be explicitly set on both the router and all the computers on your network. This provides some protection against casual or inadvertent use of your network by outsiders. It can, however, make it more difficult for your laptop to 'roam' to other networks if you also use it away from home.

3. Disable SSID broadcast

   By default, a wireless router transmits its SSID about once a second so that wireless devices can identify it and set themselves up to connect to it. But you can turn this 'broadcast' off at the router, which makes the network less visible and forces an attacker to make a specific request for the SSID. So casual outsiders will be less likely to connect to your network.

4. Turn on wireless encryption

   By default, wireless traffic is not encrypted so anyone can read it. Turning on encryption prevents them doing this. There are two kinds of wireless encryption - WEP and WPA. WEP is the oldest type and is very easily broken using simple tools. So if you have a router that only supports WEP, you might consider replacing it. WPA is much stronger, although it can also be broken. However, it's much better than WEP, even against quite determined attackers. Encryption must be configured at both the router and all the computers on your network.

5. Enable the router firewall

   If your wireless router has a built-in firewall, you should confirm that it's enabled, as this will protect against attacks on your router from the internet.

6. Disable auto connect

   Auto connect is a default on most laptops that allows you to use a public 'hot spot' without changing any settings. It is, however, quite a dangerous default setting as you never really know what network you're on. For security, auto connect should normally be turned off. If you specifically choose to connect to a hot spot in a café, you can turn it on temporarily.

There are other more complex wireless security measures, but each additional complication tends to add only a little more security - and some may have downsides.

For example, some security advisers recommend turning off your wireless router when you're not using it. It's a reasonable security measure, as it prevents abuse of your broadband connection. But it can adversely affect your broadband speed, as the provider can't distinguish between a switched-off router and a fault, and may reduce your bandwidth.

Similarly, turning off your computer rather than 'hibernating' it when it’s not in use, can reduce the possibility of it being attacked via your Wi-Fi. It's worth considering, but it will prevent you receiving internet phone calls.

Nothing's perfect - a really determined attacker could still break into your network. But as most unauthorised use of domestic Wi-Fi is opportunistic, the settings described here should be sufficient for most needs.