I have 4 servers behind a load balancer, but only 1 of them is running a particular service. I want three of them to forward requests to the fourth, based on the port. So, at present all 4 are running nginx on port 80, but only one is running the required service on port 7070.
All 4 are amazon EC2 instances running CentOS 5, behind an amazon elastic load balancer. I've setup the load balancer to forward port 7070 through to all the machines. I need server 1,2 and 3 to forward requests to port 7070 through to port 7070 on server 4 (which is running the service).
I did try a few existing question/answers here on sf, but for whatever reason i instantly lost connectivity to my servers and had to reboot; seeing as theses servers are running live services, I was suddenly nervous about trying a hit and miss approach!
So just to be clear, servers 1, 2 and 3 do not run anything on port 7070, but server 4 does. None of them are running any other type of port forwarding, so IP Tables isn't setup at all at present.