Problems with Travelin’ Man 3 add-fqdn script on raspberry pi model B

[MiguelZ]

I'm trying open ports to a VPN server in the same box that hosts incrediblepbx. I installed and updated incrediblepbx and configured the VPN (strongswan) and make a port forwarding rule in the router to the raspberry pi on ports 500 and 4500. Initially I wasn't able to connect but I followed this two threads in the forum:

http://pbxinaflash.com/community/in...-to-iptables-for-openvpn-w-tm3-running.15332/
http://pbxinaflash.com/community/in...envpn-settings-for-iptables.15372/#post-99224

I disabled iptables for a while and the connection was successful.
With iptables enabled again, I executed this line:

iptables -A INPUT -p udp -m multiport -s <<my remote ip here>> --dports 500,4500 -j ACCEPT

, and the connection was successful again.
Before trying to modify the add-fqdn script to execute the same line above using a dynamic dns name, I tested the script with the option 0 which is supposed to open all ports and I was unable to connect to the VPN.
When I executed the script, apparently no rules are added. This is the command result

The following iptables rules now are in effect for <<my dns name>>: <<my ip address>>.

Also, the command iptables -nL | grep <<my ip address>> does not show anything.
Looking inside the add-fqdn script, it apparently generates a temp file with the rules to be applied, and then it tries to write the results to the file /etc/iptables/rules.v4 using the line

sed -i '/# End of Trusted Provider Section/r '$tmpfile'' /etc/iptables/rules.v4

Looking at the file, no new rule is added, and there is not any section with the text “End of Trusted Provider Section” inside.

Any help will be really appreciated.