'Proxy' a connection

Question

I'm developing an application A that connects to remote server S on some port (>1024). For security reasons the server S only allows connections from a specific machine I with a white-listen IP-address. That's fine when running the application, but makes developing it a pain in the... lower back side. Is there a simpler way, without setting up a full-fledged VPN solution that will allow me to run a program locally on my machine, L, which will simply establish and forward the entire connection via I to S?

In brief, what I want to accomplish is that when I run the program locally, it connects to S via I, allowing it to communicate via the whitelisted IP-addresss.

Although it sounds like a MITM, it's not. A (and the host machine L) do not need to be agnostic and I have full access to every machine except the target machine S, so changing things like hosts files, network interfaces, and setting up ssh-tunnels are all fine.

All the servers are Linux (Ubuntu LTS), my local machine is a Mac running OSX.

Please provide more details about the hosts. Are they Linux or Windows machines? — Andrey, Sep 23 '13 at 21:07
Oh sorry, all the servers a Linux machines (Ubuntu LTS). My local machine is running OSX. — Faulty Server, Sep 23 '13 at 21:11
Seems like ssh tunneling would be your quickest solution, `ssh -L local_port:S_ip:app_port user@I_ip`, then point your app at 127.0.0.1:local_port. Does that not work? — Andrew Domaszek, Sep 23 '13 at 21:34
Thanks, for some reason I didn't think of an SSH tunnel, but that worked. If you post it as an answer I'll accept it. — Faulty Server, Sep 24 '13 at 09:51

score 0 · Accepted Answer · answered Sep 23 '13 at 22:06

How many ports are we talking about? If not many and they don't change then : 1. Configure your application (A) on you machine (L) to use IP/hostanme of the server I instead of S. 2. Setup HaProxy on server I to proxy all the requests from L to S.

    global
    daemon
    maxconn 256

defaults
    mode tcp
    timeout connect 5000ms
    timeout client 50000ms
    timeout server 50000ms

frontend serverI
    bind *:Y
    default_backend serverS

backend serverS
    server s X.X.X.X:Y

Otherwise you might be able to set something up using SSH tunnel between your host L and server I. Then using iptables DNAT/SNAT route traffic between server S and tun interface on I whilst pointing your application to tun on your laptop.

https://help.ubuntu.com/community/SSH_VPN

'Proxy' a connection

1 Answers1