iptables security policy for Cloudflare

iptables.sh

#!/bin/bash
iptables -F
iptables -P INPUT DROP
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT
for IP in `curl -s https://www.cloudflare.com/ips-v4`
do
    iptables -A INPUT -s $IP -p tcp -m multiport --dport 80,443 -j ACCEPT
done

# IPv6
ip6tables -F
ip6tables -P INPUT DROP
ip6tables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
for IP in `curl -s https://www.cloudflare.com/ips-v6`
do
    ip6tables -A INPUT -s $IP -p tcp -m multiport --dport 80,443 -j ACCEPT
done