Forward a port on a remote server to your local machine with an SSH Reverse Tunnel

December 4, 2010 — Say you are running a web server locally and want to show it to someone else remotely.

You have a few ways to do this:

1. Provide your local IP address to the person.
2. Setup DNS to point a domain to your local IP.

But what if your local computer is behind a NAT and you don't want to configure port forwarding on your router?

One option if you have a publicly facing server already is to create a reverse SSH tunnel with that server. This allows you to forward a port on that server to a port on your local server.

For instance, on my Mac OS X machine I open terminal and type this command:

ssh -nNT -R 3333:localhost:3333 username@yourdomain.com

This will connect to my server (yourdomain.com), and forward traffic from port 3333 on that server to my local machine. Now I can tell someone to go to yourdomain.com:3333 and that would be the equivalent of them going to localhost:3333.

Notes:

Make sure to add a rule to your IPTables config to allow inbound traffic to port 3333.