IPTables Disable Firewall

Flush all iptables firewall rules:

#!/bin/sh
echo "Flushing firewall rules..."  
iptables -F  
iptables -X  
iptables -t nat -F  
iptables -t nat -X  
iptables -t mangle -F  
iptables -t mangle -X  
iptables -P INPUT ACCEPT  
iptables -P FORWARD ACCEPT  
iptables -P OUTPUT ACCEPT  

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Source: How to: Linux flush or remote all iptables rules - NixCraft