I found masquerading made simple howto very useful and everything works just fine. But I'm not sure about the last line:
iptables -F iptables -t nat -F iptables -t mangle -F iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -A INPUT -m state --state NEW -i ! ppp0 -j ACCEPT iptables -P INPUT DROP #only if the first two are succesful iptables -A FORWARD -i ppp0 -o ppp0 -j REJECT
There is no explanation in the howto. Why is that for?
I guess it's to reject outside-to-inside traffic, but how it works? Maybe it's better to write
-i ppp0 -o eth0 (where eth0 is my local network interface)?