title: Why doesn't SFTP have an active/passive mode like FTP
body: <p>As I understand it, active and passive mode in FTP changes the port on which commands and data are sent from the client to the server which can be useful where firewalls are concerned. I think I'm also right in saying that SFTP doesn't have the same concept - but I'm not clear what nuances of the SFTP protocol make it unnecessary/undesirable to mimic that same pattern that exists in FTP.</p>