For people asking: you can create a resetfw.sh script, for iptables:

  #!/bin/bash

  iptables -P INPUT ACCEPT  
  iptables -P FORWARD ACCEPT  
  iptables -P OUTPUT ACCEPT  
  iptables -t nat -F  
  iptables -t mangle -F  
  iptables -F  
  iptables -X

chmod +x resetfw.sh

and add it for ex to /etc/cron.hourly directory

This way you can test your iptables rules and they'll get clear at every hour. Once you check they are OK you can delete this cronjob.

(NOTE: I'm typing from memory, haven't tested this)