# Take backup of iptables
cp /etc/iptables/rules.v4 /etc/iptables/rules.v4.backup
cp /etc/iptables/rules.v6 /etc/iptables/rules.v6.backup

# Flush 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

# Save changes 
iptables-save > /etc/iptables/rules.v4
ip6tables-save > /etc/iptables/rules.v6