Sun Jan 10 14:33:15 UTC 2010
David Hláčik <david at hlacik.eu>

Hello I will briefly draw the situation

Router with one interface eth0 , to local network

on a local network ADSL modem with IP

I want to use as a connection to internet .

Because of that I have created default route "ip route add default via dev eth0"

I do not want my ADSL modem to do NATing , since it shows to be slow.
I have configured static route on ADSL modem " via" which ensures traffic comming from internet will ge to
my router.

Now i want to configure NATTING. My concern is, how to create iptables
rule which will match only the traffic going via and only
for this will make SNAT.
If I will do iptables -A POSTROUTING -o eth0 --j SNAT --to-source this will not work . I need to add there a magic words
that only traffic going via should be SNATted.

Please help,

Thank you in advance.