We need to scp a file between two hosts. The problem is that the two hosts (A & C) cannot directly communicate. We can solve this using a SSH tunnel and an intermediate host (B) that can communicate with both. This also means, the command for Host B needs to run first, then the scp command for host A.:
Host A (source)
This will scp to localhost on port 3000 which is actually our tunnel to host c — /destination_file is the path on host C
Host B (intermediate)
Host C (destination)
Also, if you have spaces in the paths make sure to escape the space with \ e.g.