No, don't append the file manually. This is a much better way to do it:
Step 1. Dump the iptables rules to a file:
Code:
iptables-save > firewall-config.txt
Step 2. Edit the file you've just exported to as required, adding/amending/deleting rules as required
Step 3. Load the new rules:
Code:
iptables-restore < firewall-config.txt
Step 4. Check that everything works as expected. If it does, flush the rules:
Code:
service iptables save
If things aren't working as expected, revert to the previous ruleset:
Code:
service iptables restart
Regards
David