By default, in Mac OS X Leopard, any user can adjust the wireless network settings and connect to any available network. This may be convenient for most situations, but many users might wish to restrict non-administrator users from changing these settings.
Users should follow these steps:

1. Log in as an administrator and go to the \”Network\” system preferences.
2. Select the AirPort interface and click the \”Advanced\” button.
3. In the AirPort tab, use the plus (+) or minus (-) buttons to add or remove wireless networks, only adding desired networks to the list.
4. Uncheck \”Remember any network this computer has joined\”
5. Check both \”Disconnect from wireless networks when logging out\”
6. Check \”Require Administrator password to control AirPort\”.
7. Click \”OK\” to save changes.
8. With the advanced options closed and the AirPort interface still selected, uncheck \”Ask to join new networks\”.
9. Click \”Apply\” to save changes.