syniac said:
If you just wanted to block everything [or 'everything' specified by port rather than by server], it would be pretty effective, right?
But then how do I connect to my machine if the port is blocked? What am I gaining? If the firewall is off completely, the only things that answer to port scans are services that are listening for connections. Why are you bothering to run services if you don't want them to be connected to? The little you gain from the Apple-control firewall is that if you don't know what the hell you're doing and accidently turn on a service (that happens to be insecure) but don't open the ports in the firewall, you're at least protected from your own folly. But if you cannot effectively block IPs from services, you might as well not have a firewall running at all. Take this for example..
With the Mac GUI ipfw control.. I want to have remote access turned on (ssh, port 22). So I poke a hole in the firewall and allow access to port 22. When someone from anywhere in the world scans my Mac, they see port 22 open.
I turn off the firewall. The only service I have running that is listening for connections is port 22. Again, when someone from anywhere in the world scans my Mac, they only see port 22 open.
There's no effective difference, therefore, the firewall is pretty much worthless. I'm unable to protect my ports with the Apple control, they are either open to the world, or they are closed off completely, which doesn't do any good either, since I need to connect to my Mac with ssh. With the current spate of ssh attacks coming from asia, I prefer to protect myself as much as possible.
See the difference?
My argument is, like you said, that people typically don't know what they're doing with the firewall and just poke so many holes in it to so many inherintly insecure services, that they might as well save themselves the trouble and turn "off" ipfw, since it's not doing anything for them anyway. I guess what puts a burr under my saddle is that people want to be "secure" but don't want to spend the time to learn what that actually means. They simply want it fed to them with a silver spoon.. press this button and you're "secure".