I have a ProFTPd Server where the users can access to files using links dynamically generated in a website. The link URL follows the pattern ftp://user:password@host/path/to/file
With the new iOS 11 and new macOS, users cannot access the FTP server. They get a "don't have permission to open" error.
Surprisingly, on a Mac, hovering over the link and using contextual menu->“download attached file” will download the file.
Any iPhone or Mac running previous OS versions can download the files normally.
Looking through FTP logs confirms credentials are not sent by Safari.
Using any other browser (Chrome, Firefox) works fine as well.
Forcing users to an external app is not an option.
EDIT: I have tpcdump the connection and I see that Safari changes request user and password to: user-> anonymous pass-> email@example.com
So the FTP server rejects the connection to a anonymous user.