While it has been possible to use profiles in the Little Snitch traffic monitoring utility to create a set of rules that limit connections, you still had to remember to switch to that profile manually. With Little Snitch 3.1, Objective Development has added a new Automatic Profile Switching capability that enables you to assign a network (such as your home Wi-Fi network or a coffee shop hotspot) to a specific profile. When you first connect to a network, an alert window pops up to ask which profile you want to assign to the network. You can also choose to do nothing or configure a default profile that will be used for all unknown networks. No network traffic is allowed while the alert window is open to prevent email and file synchronization accounts from sending and receiving data in unwanted situations. Other changes in Little Snitch 3.1 include an improved Restore Factory Defaults feature, a bug fix for a rare issue that could cause a kernel panic, and an updated help section covering the addition of Automatic Profile Switching. ($34.95 new, free update, 13.2 MB, release notes)
Smarter Parental Controls
If you've been using the parental controls options in Mac OS X to lock your child out of using a particular computer late at night, but would like to employ a more clever technique to limit Internet access, turn to MAC address filtering on an Apple base station.
To do this, launch AirPort Utility, select your base station, and click Manual Setup. In the Access Control view, choose Time Access to turn on MAC filtering. You'll need to enter the MAC address of the particular computer, which (in 10.5 Leopard and 10.6 Snow Leopard) you can find in the Network System Preferences pane: click AirPort in the adapter list, and click Advanced. The AirPort ID is the MAC address.