I've been searching and reading on a solution to my problem. I would like to block all traffic except on specified port range (55556-55560) on specified NIC (eth0). And then block all traffic on the same port range on another NIC (eth1).
I'm running a Ubuntu Server 12.04 system with two physical network interfaces (eth0 and eth1). eth0 is tunneled through a VPN tunnel on the tun0 interface and i've only got one application bound to that interface.
What i've now encountered is that other internet services like swsh and apache2 web server is also avaliable on the external ip of the tun0 interface and i don't want i to be.
The application running over the VPN tunnel runs on port range 55556-55560 and now i only want to allow these ports on the eth0 interface. The other interface (eth1) is behind a router so i don't want any port rules to be applied there.
How do i accomplish this in the best manner. Is ufw the best solution and how do i config i correctly
sudo ufw allow 55556-55560 on eth0
returns a error. (Wrong number of arguments.)