On Sun, Jan 10, 2010 at 6:33 AM, David Hláčik david@hlacik.eu wrote:
Hello I will briefly draw the situation
Router with one interface eth0 , to local network 10.123.0.0/16
on a local network ADSL modem with IP 10.123.10.11
I want to use 10.123.10.11 as a connection to internet .
Because of that I have created default route "ip route add default via 10.123.10.11 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 "10.123.0.0/16 via 10.123.10.11" 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 10.123.10.11 and only for this will make SNAT. If I will do iptables -A POSTROUTING -o eth0 --j SNAT --to-source 213.194.242.198 this will not work . I need to add there a magic words that only traffic going via 10.123.10.11 should be SNATted.
Unless the machine running iptables has a NIC with a IP address of 213.194.242.198 I don't believe it's possible with ipchains.
The MODEM is the interface between 213.x and 10.y networks.
If you created a DMZ by moving your LAN to say the 192.z network (or a different 10.y network) then you should be able to get it work with 2 NICS in the ipchain machine.
In this case, you would route between the 10 network and the 192 network with 2 NICs and SNAT the 10 network.
The WAN would be the 213.x network, the DMZ would be 10.y, and the LAN would be the 192.z network.