u-restrict-by-primary-group-only NcFTPd general.cf file configuration
Don't forget to restart NcFTPd after modifying the general.cf file.

If you chose to restrict groups, the server will consider a user restricted if that user is a member of any restricted group, primary or supplementary.  If you would prefer that the server restrict a user only if her primary group (the one in the /etc/passwd file) is a restricted group, then set the u-restrict-by-primary-group-only variable to yes.

Examples:

Recommendation:
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