This page allows you to configure what the FTP server logs, and where it logs to. The options available are :

Log all commands for
  Users of the selected types will have every command logged
Log transfers for
  Users of the selected types will have transfers in the selected directions logged.
Log transfers to
  Determines whether transfers are logged to `syslog`, or the WU-FTPd `xferlog` file, usually `/var/log/xferlog`.
Log security violations for
  Users of the selected types will have have security violations logged to `syslog`