title: How can I listen for changes on a (S)FTP server?
body: <p>I am downloading intra-daily files from several (S)FTP servers. These servers are not managed by me, I have been granted access by external parties.</p>
  
  <p>The files arrive at different points of time in the day. I cannot therefore not know beforehand when I have to send an extraction request.</p>
  
  <p>Is there a smart way to setup a listener to track changes on these SFTP server? Eg some kind of ping that returns the last updated timestamp of the server.</p>