How can I secure my wifi so others can't use it?

From Digital Economy Act Info

As with most security, you can never make it entirely secure, but you can deter people from trying, resulting in them moving onto a softer target or giving up. Recent research shows that 45% of wifi connections are unprotected or easily crackable [1].

Exactly how to achieve the following steps will vary massively depending on the make of your wifi router, so please refer to their websites and documentation for specific instructions.

• Turn on encryption: Most domestic Wifi kit these days support encryption. Some such as Sky come with it turned on by default but many do not. There are normally two types on offer, WEP and WPA. These days WEP is very easily defeated so always go for WPA. This offers a considerable level of security, but WPA is still defeatable given sufficient time.

• MAC Filtering: This ensures only the devices you authorize can connect to your wifi router. This provides some protection against casual attempts to access your wifi, but as the unique identifier it uses to identify each PC (the MAC address) can be forged, it's not entirely secure (it also doesn't stop people "reading" your wifi out of the air).

• Disabling SSID broadcasting: This prevents your wifi being seen by many commercial products (such was Windows), but there are plenty of free and readily available software tools that get around this, so it provides very little protection.

Even if you take all these precautions, some risk remains.

Wifi can be detected at long distances

Please note that the distance at which your wifi signal can be used is a lot bigger than you might think.

Using a simple aerial such as a Cantenna or a Woktenna pointed at your home, it is possible to tap into the network from quite a distance. (Cantenna ~ 100m+, Woktenna - 1km+). So it is quite possible for your network to be subverted by people that will be too far away to see or even simply hidden behind a curtain in a flat window in a towerblock.

Remember, a cracker cannot break into a network if it is turned off. If you do not need Wifi access to your connection, then please consider turning it off (especially if you are in a built-up area).