I'm having some issues trying to forward traffic from a specific port on eth1 to an ip address and port on eth0.
For example 192.168.3.1 is my usb 4g stick and where my ddns is going to, eth1 is sitting on 192.168.3.10, and i need to forward traffic from outside on the ddns port 15201 through the pi on eth0(192.168.1.1) to 192.168.1.101:15201. I've got about 4 different ports to do.
I've allowed ipv4 forwarding and now i've got to iptables and i'm baffled, i've been trying along the lines of;
iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 15201 -o eth0 --destination 192.168.1.101:15201 but it won't stick..! and is saying host/network not found.
Is anyone able to help - as i'm starting to go bald!
Also, is there an easy way to create eth1 as the default nic and gateway?