I would think then that you need to look at the setting on your router and make sure it's not misconfigured. And/or looking into getting a static IP from your ISP so you can skip all the DHCP foolishness with your router's IP. But, I don't think that your router should be requesting a new DHCP address for itself every hour or so. Of course, this could be a problem on your ISP's end as well. If they are having troubles with their routers or DHCP servers..

Tcp wrappers allows you to restrict connections not only from only specific source IP's, it allows you to restrict connections from specific users coming from specific IP's, using specific protocols. I don't think IPFW is quite that granular.

Nope, ipfw cannot do that. Thanks for the info.

I returned NAT to normal and the finally reset the router to factory defaults and flushed ipfw as well. Still I'm getting new IP's every couple of hours. Performance is not as good as it once felt in Safari (although I'm probably getting used to it), even though bandwidth speed tests still come out roughly the same. Things are better in Camino.

Thanks for your help. I'm going to use ifpw to restrict the range tightly as yellow suggested earlier. I can't use tcp wrappers, it seems, because I don't have a fixed ip address.

Thank you for your help everyone. I learned what I needed to know for now (although I have a long way to go overall).

I think I have the dynamic nature of the IPs figured out.

I can set it so that the connection is "when needed", "manually", or "always on". By default, it is set to be "when needed". So I'm guessing that after awhile it probably timed out and disconnected on its own; why it reconnects on its own (gets a new IP) I'm not sure. Perhaps it gets a new IP upon mouse movement or something like that.

At any rate, I set it to "always on" and I've had the same IP for the last 24 hours. I'm not sure what I'll do long term.