When you run the server in verbose mode (ncftpd -v) or very verbose mode (ncftpd -vv), debugging messages are also logged. Those debugging messages are useful because you can see the exact FTP conversation between NcFTPd and the remote client, along with diagnostic information.
The name of the log is actually a magic cookie string, where cookies representing time are expanded using strftime(3). For example, a log name of /var/log/ncftpd/misc.%y%m%d would create daily logs named /var/log/ncftpd/misc.971009, /var/log/ncftpd/misc.971010, etc.
Examples:
