echo 1 > /proc/sys/net/ipv4/ip_forward
echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/60-ipv4-forward.conf
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables -t filter -A FORWARD -i eth0 -o dns0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -t filter -A FORWARD -i dns0 -o eth0 -j ACCEPT
iptables-save > /etc/iptables.rules