Setting up IP Passthrough on Linux

ahbarrera78

Hello,

I am running an embedded linux kernel version 3.14. My system has two network interfaces, a 4G LTE modem (ppp0) and an ethernet port (eth0).

I would like to setup IP Passthrough on my box, basically sharing/passing my 4G modems public IP to a single device connected to eth0.

When searching IP Passthrough, it seems that many products support this, but I only find instructions on how to configure those products that support IP Passthrough, not how to accomplish it myself in Linux so I can add this feature to my own product.

If anyone could help me out with any info, even any clues to get me searching in the right direction, I would really appreciate it. My current thought is that it is done through iptables, but I am hoping to find out if that thought is correct before I spend weeks learning about iptables.

Thanks in advance! - Anthony