When you join a Wi-Fi network, be aware of a few basic security cautions.
If you've set up your own AirPort wireless network, encrypt the network and set a network password. AirPort Admin Utility allows you to choose WEP or WPA2 security. WEP is not very secure. WPA2 is much stronger and very secure, using the Advanced Encryption Standard (aes). Page 172 shows how to turn on AirPort security using AirPort Admin Utility.
Turn off "Personal File Sharing" (in Sharing preferences) if you're not using it. You don't need it to open web pages or send and receive email (see page 155).
Turn on your laptop's firewall to prevent uninvited connections (see page 155).
A computertocomputer network (also known as an ad hoc network) lets you share files directly with another computer with a wireless card, even when there's no Internet connection at all. You should protect this network with WEP security. WEP is not as secure as WPA2, but it's the only option when you create an ad hoc network. You can choose between 40bit and 128bit (128bit is more secure, of course) encryption from the "WEP key" pop-up menu. See pages 189190 for details about how to set up and use a computertocomputer network.
