Wireless networks are less secure than wired ones, if only because tapping on a wired network requires physical access to the cables, while anyone with the right radio can listen in on a wireless connection. The designers of Wi-Fi made things worse with a badly flawed security protocol, named Wired Equivalent Privacy (WEP), that fails to prevent anyone with the right software tools from listening in on network traffic using an ordinary computer.

Protect Your Wi-Fi Network

A newer security protocol called Wi-Fi Protected Access (WPA) provides much better security, but is not yet widely used for public hotspots—which typically rely on WEP or are completely open. This means someone could snoop on your network activities, though watching what you are doing in detail would require a lot of work. The real danger is that it’s fairly easy to snatch usernames and passwords sent on open networks.

That doesn’t mean that using these networks for confidential transactions is completely hopeless. A secure Web server—which I hope is what your bank, for example, uses encrypts traffic from end to end, so anyone who intercepts it will only see gibberish. The address of a secure sever will begin with “https://” (instead of “http://”) and you should be able to see this in your Web browser’s address bar. If you are using the Mozilla Firefox browser, the address bar will turn yellow if you have a secure connection. You should always use the latest version of your browser (Internet Explorer 7 or Firefox 2) and make sure you have installed the latest updates.

Although e-mail messages can be encrypted, they generally aren’t, whether you are on a wired or wireless network. Think of them as postcards: People aren’t supposed to read them in transit, but since they can, you have to assume some people may. Unless you know you have a secure, end-to-end connection, e-mail should never be used to send any information that you expect to remain confidential.