When tying to start iptables on a server, you receive an error as below. Further checking, I found that the required modules for iptables to work are installed/enabled. Still this error.
Quoteiptables: Applying firewall rules: FATAL: Module ip_tables not found.
iptables-restore v1.4.7: iptables-restore: unable to initialize table 'nat'
Error occurred at line: 2
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
I had a check at the rules and there were few rules due to which iptables was unable to start. Try flushing the iptables rules OR remove the ones which are incorrectly set.
Try starting iptables & it should work properly.