#! /bin/sh

# enable IP forwarding
echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
echo 1 > /proc/sys/net/ipv4/conf/default/forwarding
echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
echo 1 > /proc/sys/net/ipv6/conf/default/forwarding
echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter
echo 0 > /proc/sys/net/ipv4/conf/default/rp_filter


iptables -F
iptables -t nat -F

iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT


iptables -A FORWARD -i eth0 -s 172.31.54.0/255.255.255.0 -j ACCEPT
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

iptables -A INPUT -p icmp --icmp-type 8 -j DROP
ip6tables -A INPUT -p ipv6-icmp --icmpv6-type 8 -j DROP


iptables -A INPUT -p tcp --destination-port 53 -j ACCEPT
iptables -A INPUT -p udp --destination-port 53 -j ACCEPT
iptables -A INPUT -p tcp --destination-port 80 -j ACCEPT
iptables -A INPUT -p udp --destination-port 80 -j ACCEPT

ip6tables -A INPUT -p tcp --destination-port 53 -j ACCEPT
ip6tables -A INPUT -p udp --destination-port 53 -j ACCEPT
ip6tables -A INPUT -p tcp --destination-port 80 -j ACCEPT
ip6tables -A INPUT -p udp --destination-port 80 -j ACCEPT

iptables -A INPUT -p tcp --destination-port 1:65535 -j DROP
iptables -A INPUT -p udp --destination-port 1:65535 -j DROP

ip6tables -A INPUT -p tcp --destination-port 1:65535 -j DROP
ip6tables -A INPUT -p udp --destination-port 1:65535 -j DROP