#!/bin/sh echo "Only FTP access is allowed with this account." exit 0and make it executable:
chmod a+x /usr/local/bin/ftponlyThen make it the user's shell:
chsh -s /usr/local/bin/ftponly <user>Test it: Try to login to this account with ssh, you should be denied Alternately, some ftp server all virtual users. ie users who aren't Linux users.