/sbin/iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
/sbin/iptables -A FORWARD -i ppp0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
/sbin/iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
/sbin/iptables -A FORWARD -i 192.168.39.1 -o ppp0 -j ACCEPT