NAT Problem

ajkannan83 · 08-05-2010, 06:52 AM

Dear Sir,

We are using Broadband 2 Mbps (India) connection in Redhat Linux 5.
In Server there are two network card.

One is connected to Broadband another one is connected to LAN

that means

Eth0 Address : 192.168.0.5/255.255.255.0 gateway 192.168.0.1

Eth1 Address : 10.0.0.5 /255.0.0.0

How to configure NAT in Linux Machine

#iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 192.168.0.5
#echo 1 > /proc/sys/net/ipv4/ip_forward

Is this correct or not?

estabroo · 08-05-2010, 07:08 AM

Seems reasonable, though you also want to turn on ip forwarding in your sysctl.conf file so that your forwarding persists over reboots and shutdowns

szboardstretcher · 08-05-2010, 09:40 AM

http://lmgtfy.com/?q=2+card+nat+iptables

There are millions of examples of doing this with IPtables. 100's of them are on this forum.

Try and do some research before asking a question that has already been asked and answered over and over again.

iptables --table nat --append POSTROUTING --out-interface eth1 -j MASQUERADE
iptables --append FORWARD --in-interface eth0 -j ACCEPT

I wouldnt bother using iptables. Get OpenBSD and use pf(). Of course, that would mean reading the manual though.