Reverse port forwarding

Accessing your local development server from the outside world.

It’s often the case that you have a local development server that you wish you could access over the interwebs. Perhaps you need to do a demo, show a prototype to a colleague, or integrate with external servers that can’t connect directly to your laptop.

In the past I’ve gone through a laborious hack→build→push→run→test cycle that is slow and inefficient.

Enter reverse port forwarding, the age old technique of SSH Tunneling.

All you need is access to a remote server that can be accessed from the outside world, such as an EC2 instance or a VPS.

First off, log in to your remote server and open /etc/ssh/sshd_config. If it does not already exist add the line:

GatewayPorts clientspecified

Then restart the SSH daemon:

sudo /etc/init.d/ssh restart
# or
sudo service sshd restart

Back on your laptop, start your development server and then in another terminal run the following:

ssh -N -R :3000:localhost:4000 user@12.34.56.78

This will forward requests to port 3000 on your remote server to port 4000 on your laptop. Visiting http://12.34.56.78:3000 will be handled by your laptop.

(Substitute ports and IP addresses as appropriate.)

That’s it.