Access control defines user access privileges to files in the system. Access control prevents unauthorized or accidental use of files. After you enable access control on an FTP server, all access users are controlled.
After a user fails to log in to a device using FTP, the number of FTP login failures is recorded for the IP address. If the number of login failures within a specified period reaches the threshold, the IP address is locked, and all users who log in through this IP address cannot set up an FTP connection with this device.