Generating Firewall Rules with Perl

With all of the evil-doers on the Internet, even most new computer users understand the importance of having a secure firewall.

Mike Diehl is a freelance Computer Nerd specializing in Linux administration, programing, and VoIP. Mike lives in Albuquerque, NM. with his wife and 3 sons. He can be reached at


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Error in add_good_hosts subroutine

sebyte's picture

Hi Mike,

Trying to get this working.

I've only one good host, namely loopback so my good_hosts.conf looks like this: loopback

and I'm getting the following error on stdout when I run the script:

Setting IP forwarding to 0.
Try `iptables -h' or 'iptables --help' for more information.
X: (512) iptables -A INPUT -s loopback -j ACCEPT
Try `iptables -h' or 'iptables --help' for more information.
X: (512) iptables -A OUTPUT -d loopback -j ACCEPT
Setting IP forwarding to 1.

I'm not much a Perl coder I'm afraid, and by the looks of it it's an iptables issue rather than a Perl issue.

Any help much appreciated.


Error in add_good_hosts subroutine

Mike  Diehl's picture

Are you putting a TAB after the IP address, or a SPACE? The script splits on tab. I'll bet this fixes your errors.

Email me directly if it doesn't. My address in in the article.