Expose a service running on your local machine (e.g. a local dev web server) on a remote host by forwarding a port on that remote host back to your local port using ssh -R, so processes on the remote side can reach your local service.

Documented steps

1. Confirm the local service is listening, e.g. a dev server on 127.0.0.1:3000 on your workstation.
2. Start the tunnel from your local machine: `ssh -R 8080:127.0.0.1:3000 <user>@remote-host`. Syntax is `-R [bind_address:]port:host:hostport` -- port is opened on the REMOTE host, host:hostport is the destination reached FROM your local machine.
3. On the remote host, verify the forwarded port is listening: `ss -ltnp | grep 8080` or `curl http://127.0.0.1:8080`; by default it is reachable only from the remote host itself.
4. To make it reachable from other hosts on the remote network, pass an explicit bind_address, e.g. `ssh -R 0.0.0.0:8080:127.0.0.1:3000 <user>@remote-host`, AND set GatewayPorts to yes or clientspecified in the SERVER's /etc/ssh/sshd_config, then reload sshd -- the client bind_address only takes effect if the server allows it.
5. Run non-interactively and detached if desired: `ssh -f -N -R 8080:127.0.0.1:3000 <user>@remote-host`.
6. Tear down by killing the backgrounded process (`ps aux | grep '[s]sh -f -N -R 8080'` then `kill <pid>`).