The Firestarter firewall wizard is automatically launched when you start the program the first time. If you want to return to the wizard at a later time, it is also accessible from the Firewall menu in the main interface. All of the choices made in the wizard can however also be changed through the preferences.
This page of the wizard is for configuring the primary network device; that is, your Internet connected network adapter.
The wizard automatically discovers all devices that are currently present in your machine. Generally, you will use either a pppxx or ethxx device, unless you have some special hardware. ppp is usually associated with a dial-up device while eth is the norm for most broadband connected machines.
Some cable modem users might have to select ppp0 as their device, even if there is also the choice of selecting eth0. This is because of the PPPoE protocol used by their ISP. If you see a ppp device in the list, and you do not have a modem, you probably must select it as your network device.
The following two options are available:
Internet connection sharing allows several machines to access the Internet trough a single network connection. This is done using NAT. To the outside world the group of machines will look like a single machine with a single IP address.
For NAT to work you need two or more network devices in your machine. If you only have one device this page will not show in the wizard. To enable NAT, simply select a device from the drop down list of autodetected devices. You must select a device other than the one you selected on the previous page.
For an in-depth look at the subject, as well as how to configure the DHCP service, read our guide to Internet connection sharing. Generally however, both NAT and DHCP will work out of the box simply by enabling them in the wizard, without the need to configure anything.
At the final page you have to option to either discard your changes or accept and save your choices. As soon as you click save, the firewall is started.
At this point Firestarter will be working in its default secure mode and there is no immediate need to further configure anything. The default mode implements a restrictive policy for incoming traffic and a permissive stance towards outgoing connections. For more information about the default mode of operation and how to change it, refer to the section on creating policy.