"To transfer a file from the laptop to the desktop tried `scp ./<filenamd> salmo'. That failed. So did adding the port option. What am I missing?"
The correct scp command syntax is scp [file_name] remoteuser@remotehost:/remote/directory Because it's SECURE copy, you have to provide user login credentials as well as the directory you want the file copied to. Reference - https://www.geeksforgeeks.org/scp-command-in-linux-with-examples/
