Mac OS X Leopard - ARCAism

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CHAPTER 20 LEOPARD NETWORKING
Figure 20-1. Firewall settings in System Preferences
On the BSD level, Mac OS X has switched from running ipfw to running socketfilterfw.
Aside from eliminating the hassle of manually configuring ports, the socket filtering method is
more accurate, because it filters packets based on where they are going, rather than which port
they are coming into.
The new firewall has very few configuration options. First, there’s the level of firewall activity.
Your choices are to allow all connections, which is rarely a good idea, or to block all
connections, which would be a good idea if all you do is surf the Web, but a bit draconian
otherwise.
NOTE There are a few times when it might be necessary to have the firewall allow all connections.
If you’re behind a dedicated firewall, it might be redundant. If you’re having trouble
connecting to another machine, you might need to temporarily disable the firewall. Finally,
your network administrator, who has the last word on network configuration, might ask you to
keep it open.
Figure 20-2. Automated firewall management dialog
The best option is usually to limit
incoming connections to specific services
and applications. You can add and remove
applications and set whether incoming connections
should be allowed or denied.
What makes the limit option so compelling
is that you don’t need to actually add
any applications to the list. When you
launch an application, it will let you know if
it wants access through the firewall with a
dialog, as shown in Figure 20-2.