NcFTPd general.cf file configuration
Don't forget to restart NcFTPd after modifying the general.cf file.
The port setting configures which TCP/IP port number NcFTPd listens on. The default is port 21, which is the standard FTP control connection port number. The server also requires that it can use the port numbered one less, for the data connection. Again, with a standard setup, that would mean that NcFTPd uses port 21 and port 20.
Using a non-standard port number is not very useful. It can be helpful when you want to run multiple FTP services, but with NcFTPd you should be able to do everything you want on the standard port number.