NcFTPd general.cf file configuration
Don't forget to restart NcFTPd after modifying the general.cf file.
You can try this option if you wish to force the use of binary transfer type for uploads. Most modern FTP client programs automatically switch from ASCII to binary automatically, but older programs and buggy programs still exist.
When this option is set to no, if the user tries to download in ASCII, the transfer is disallowed and an error message is sent back instead. An example of the error message is shown in boldface below:
Note that the FTP protocol does not allow the server to set the default transfer type to binary. The protocol specifications require that default be ASCII and that the transfer type only be changed by the client, so NcFTPd cannot automatically set the transfer type to binary.
The consequences of all this is that you can't have NcFTPd use binary by default. Even if you set this option to no, it won't solve the problem of binary data files being corrupted in ASCII mode, unless the user knows how to change to binary.