yaig is an iptables rule generator designed to take a config file and turn it into iptables rules.

ie:

object local    127.0.0.1

object shodan1 198.20.69.96/29
object shodan-io2 66.240.192.0/18
object shodan-io3 71.6.128.0/17

group shodan
    object shodan1
    object shodan-io2
    object shodan-io3
    
    
server group shodan drop
server object local accept

to

-A INPUT -s 198.20.69.96/29 -j DROP -m comment --comment "server - Group: shodan - drop"
-A INPUT -s 66.240.192.0/18 -j DROP -m comment --comment "server - Group: shodan - drop"
-A INPUT -s 71.6.128.0/17 -j DROP -m comment --comment "server - Group: shodan - drop"
-A INPUT -s 127.0.0.1 -j ACCEPT -m comment --comment "server - Object: local - accept"

natefw would be my first attempt at this concept.