Sharing a Connection through a Computer
It's sometimes very useful to share your computer's existing Internet connection with another computer. You might want to share an AirPort Internet connection with other computers on your wired network. Alternatively, if you've set up an ad-hoc Wi-Fi connection, as explained in Chapter 15, “Configuring Your Wi-Fi Network,” and you have Internet connectivity, you might want to share your connection with your wireless friends.
Sharing, as I tell my kids, is good. And sharing an Internet connection can be very useful. But it does pose some security concerns. So if you are not actively sharing your Internet ...