This is the best solution to prevent unauthorized files from being copied to the server via FTP because anonymous access allows anyone to log in to the FTP server without providing a username or password. Disabling anonymous access will require users to authenticate with valid credentials before accessing the FTP server. References: https://docs.microsoft.com/en-us/iis/configuration/system.applicationhost/sites/site /ftpserver/security/authentication/anonymousauthentication