How do I connect my Mac to a WPA Wireless network?

My colleague Chris Buechler and I went back and forth trying to figure out exactly what you're asking, and here's what Chris finally came up with: If I understand your question, it sounds like you have configured WPA on your Linksys wireless access point and your Powerbook, but you're not sure about your WPA Pre-Shared Key.

WiFi Protected Access, WPA, is an encryption standard for wireless networks, and is currently the most common standards-based strong encryption for wireless networks. The WEP protocol, Wired Equivalent Privacy, was the original encryption protocol designed for WiFi networks which WPA was designed to replace due to insecurities discovered in WEP.

The problem with any type of wireless network encryption is the relative difficulty of getting machines connected to the network. This is one reason the vast majority of wireless networks, especially home and small business wireless networks, do not employ any type of protection. It can be difficult to get your own machines configured properly, much less visitors' laptops.

To change your WPA Shared Key, log into your Linksys, click the Wireless tab, and click Wireless Security. There you will see a box labeled WPA Shared Key. Change it there, make note of what it is, and click Save Settings. You can then enter this key into your Powerbook, and subsequently any visitors' laptops.

On your typical small office/home office grade wireless access points, you cannot configure multiple wireless networks on a single device (most enterprise class access points do permit this, though at a much higher cost). Each wireless network can either use WEP, WPA, or no protection. That is, you cannot use WPA on your laptop, and still connect visitors' laptops to an open network.

Unfortunately there is no easy solution. You can try to use WPA on all visitor laptops, and if they're running OS X or Windows XP, that should not be much of an issue. With older laptops, that might not be feasible. You could disable WPA while you have visitors and enable it at all other times. There are alternatives that allow you to run a second, open wireless network segregated from the rest of your network and protect it through other means, but are well beyond the scope of this answer and difficult at best for someone without a decent amount of networking knowledge.

For more information about safe wireless network use, you'll want to check out our Connect Safely Wireless Security and Privacy Guide.