I have a process running on my Ubuntu 12.04 server that insists on binding to a public IP address. I only want it accessible from localhost, and NOT the outside world. I've been trying to work out a way to forward 188.8.131.52:8888 to 127.0.0.1:8888. I saw something about iptables not wanting to forward connections to loopback, and I haven't been able to make it work with xinetd either. It's also important that the connection not only be available on localhost, but be inaccessible on the interface it's trying to run on. Is this even possible?
Replace eth0 with whatever interface you want to block connections from. If the application communicates in UDP, replace tcp with udp, or just apply both.