How to expose a Flask local development server to the public using SSH remote port forwarding

Here is how to run a Flask local development server on your local machine and expose it to the public via a remote server you have control over. This uses SSH remote port forwarding which is a converse of local port forwarding described here: How to run a Django local development server on a remote machine and access it in your browser on your local machine using SSH port forwarding

1. On the remote host, edit the sshd_config file (mine was located at /etc/ssh/sshd_config) to allow remote hosts to connect to ports forwarded for the client:

   GatewayPorts yes

2. On the remote host, restart the SSH server:

   $ sudo service sshd restart 
   

3. On the local host, SSH to the remote host:

   $ ssh -v -R 50051:localhost:5000 [email protected] 
   

4. On the local host, run the Flask dev server:

   $ python runserver.py localhost 5000 
   

5. Go to http://my.remotehost.com:50051 in the browser

Using RemoteForward in your ~/.ssh/config

You can also achieve the same results by using the RemoteForward in your ~/.ssh/config file:

Host myremote
  User eliot
  HostName my.remotehost.com
  RemoteForward 50051 localhost:5000

References

• http://www.hackinglinuxexposed.com/articles/20030309.html
• http://serverfault.com/questions/285616/how-to-allow-remote-connections-from-non-localhost-clients-with-ssh-remote-port
• http://linux.die.net/man/5/sshd_config

See also

localtunnel by Jeff Lindsay exposes your local development server without requiring a public remote server.