title: Enable logging in Apache Commons Net for FTP protocol
body: <p>Apache Commons Net library does not seem to send anything to any "logger".</p>
  
  <p>Can I somehow obtain a log file from an (FTP) session, for debugging purposes? For example raw FTP commands and responses from the server, like this:</p>
  
  <pre class="lang-none prettyprint-override"><code>220 Welcome
  USER *******
  331 Password required for ...
  PASS *******
  230 Logged on
  TYPE I
  200 Type set to I
  QUIT
  221 Goodbye
  </code></pre>