This is useful if you are trying to transfer files from server A to C, where C is behind a firewall. An example is if you want to scp files from your home computer to a server within the AOS network. This will require in intermediary server B and in our example this is our SSH Gateway, mercury.atmos.ucla.edu. Put the following into your ~/.ssh/config file.

Host hostname.atmos.ucla.edu
User username
HostName hostname.atmos.ucla.edu
ProxyCommand ssh username@mercury.atmos.ucla.edu -W %h:%p -q

After putting this in you can simply run the command ssh hostname.atmos.ucla.edu. This will tunnel you through to your target host. The -W %h:%p is doing the forwarding and -q is simply suppressing output errors.

WIP