Help with ipfw to iptables conversion?

[Scott R. Ehrlich]

I have a firewall ruleset from an OS X system I want to convert to 
iptables for use on a Linux box.    Is there any sane way to convert the 
ruleset next to going line by line and learning ipfw's rules, and working 
on trying to figure out the corresponding iptables way of doing it?

Thanks.

Scott