@cewebugil As far as your original question is it is sufficient to apply IPTABLE rules.The moment you apply IPTABLE rule it immediately becomes active.But it will not survive a reboot.
To be able to survive IPTABLES a reboot in your network configuration file /etc/network/interfaces file (I am referring to a Debian/Ubuntu system) you need to add some where
pre-up iptables-restore < firewall.txt
Check this thread confusion in setting up a firewall on bridge and this link
Two good practises to save your self from a lock
1) It is always a good idea while testing IPTABLES to have a cron job entry that flushes your rules every 15 minutes or so.So that if you by chance apply wrong rule after 15 minutes that rule is deleted and you can login again.That will save you from a possible lock down if some IPTABLE rule was wrong.
2) This can also be done by
iptables-restore < iptables_rules; sleep 30; iptables-restore < clean_rules
The idea is apply the rules, wait 30 seconds and apply a set of rules to allow all access. When you execute this line, press enter a couple of times and two things can happen:
Your rules locked you out (pressing enter does not show on the screen, so wait the time to run out and they will be cleared;
If your rules work and you can see the new lines on the screen, CTRL+C before the sleep ends and you're good.