The best way to ensure the security of your wireless network by far is to perform your own regular security audits. Far from being a complex task, performing an audit involves taking many of the same steps that a hacker might use to try and compromise your network, and using common “tools of the trade” like Network Stumbler and AirSnort. To perform an audit, grab a Wi-Fi equipped laptop or PDA, and then take a walk. Literally position yourself in different areas within and around your home or office, and then try to connect to your network. Keep in mind that Wi-Fi signals can often extend to ranges of up to 1000 feet, so a trip to your parking lot or different floors of your building may be in order.
Your best bet when performing an audit it to start off by configuring the wireless network card in your laptop of PDA with the default security settings, which usually means that no security settings (like WEP or WPA) are enabled. Then, try to associate with different access points on your network. Install and use Network Stumbler to determine whether your network is visible, and how many of your network’s settings this tool can obtain.
Many of the client utilities included with wireless network adapter cards include the ability to scan for additional networks in a manner similar to Network Stumbler. You may be surprised at how many networks you find in your vicinity that you never even knew existed. If you do come across other networks whose owners you recognize (by their SSID value, for example), be sure to let them know of the potential security risks they face. Another benefit of doing so is that you might find that a “neighbour” is using the same wireless channels on their network as you are, which would provide the opportunity for you both to move to a distinct channel, potentially reducing interference and improving performance.