iptables -F
iptables -t nat -F
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP
iptables -I INPUT 1 -i usb0 -j ACCEPT
iptables -I INPUT 1 -i lo -j ACCEPT
iptables -I FORWARD -i usb0 -d 192.168.0.0/255.255.255.0 -j DROP
iptables -A FORWARD -i usb0 -s 192.168.0.0/255.255.255.0 -j ACCEPT
iptables -A FORWARD -i eth0 -d 192.168.0.0/255.255.255.0 -j ACCEPT
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward
for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done