Subject: Re: [44net] Trouble creating a Gateway into 44net From: "Augustine Tabeling, W8AWT" w8awt@qsl.net Date: 03/24/2017 12:36 PM
To: 44net@hamradio.ucsd.edu
"An alternative when you do not want to do as much on your brother's computer
and do have a Linux system yourself, is to just forward all IPIP traffic received by your brother's computer to your computer over the local network, and run ampr-ripd etc on your own computer. "
This is exactly what I want to do but I have no Idea how to do it. By "all IPIP traffic" do you mean _only_ the IP Protocol 4 Traffic or do you mean effectivly all IP traffic (I dont think that would be ok.)? I ask this because my brothers computer has several websites and a few other web services (IRC, SSH, FTP, Minecraft) running on it and everything that I do cannot interfere with them.
On a Linux system, this is easy. IPIP stands for "IP in IP" which is the protocol that is used for AMPRnet tunnels. The outer IP packet has protocol 4, the inner IP packet is the actual packet to be transferred. Use the following command to send all incoming IPIP traffic (IP protocol 4) to another system using a destination NAT rule:
*|iptables -t nat -A PREROUTING -p 4 -j DNAT --to-destination 1.2.3.4|*
Instead of the 1.2.3.4 you put the IP address of your own computer. The replies to those packets can be sent directly to the router so it is not required to configure a reverse for this. (assuming the router does NAT itself)
This command has to be repeated every time the computer is booted. To do that, you can add it to the file /etc/rc.local
Rob