I often read stories of raids on homes where it was thought the occupants were downloading illegal movies, music and images only to find their wi-fi was hi-jacked by a neighbour!
Its also not uncommon to read about innocent internet users receiving fines accusing them of illegally download music and been taken to court over it!
Most new wireless routers come with security already enabled out of the box. However, not all do and its best to double check. If your purchased your own router, or still use an old router provided by your internet provider several years ago it is possible your wifi could be unsecured.
Even using the older WEP security is not secure enough these days and anyone with a laptop and some free downloadable software can easily crack the WEP key and gain access to your network.
I always recommend using the best security your wireless router can offer which is listed below (in order or least secure to the most secure):
WEP – only as a last resort – the lest secured (but better than no security at all – just!).
WPA – Ok security, make sure you use a long difficult password (see password section above).
WPA with TKIP – Pretty good security and combined with a decent password will be excellent.
WPA2 with AES – Excellent security, combined with a decent password will ensure no one will be able to access your network.
If your router has “Guest Wireless” support then enable this for your friends and visitors to use. This will ensure they wont have full access to your own network ensuring all your computers cannot be accessed.
Lastly, ensure your router’s default admin password is changed to ensure no-one can gain access to your router (which in turn will allow access onto your network and they could even kick you off the network!).