Portable firewall rules for Linux and Free/Net/Open/DragonFlyBSD

http://www.fwbuilder.org/

Firewall Builder supports a wide range of firewall platforms, including Cisco ASA & PIX, Linux iptables, BSD pf and many more. You’re not confined to one platform—or locked into a single vendor.

See the intro: http://www.fwbuilder.org/4.0/docs/firewall_builder_intro.html

Such conversion is not always possible, since different packet filters have different logic and packet processing scheme. For example, there is no simple and straight way to convert iptables rules (with all those tables and chains) to ipfw or pf rules. It's better to just write new ruleset for needed firewall type with knowing what you need to get in the end.