How to open access for ddns in ftpaccess?

Question

System administration

Good afternoon!
There is a problem, you need to open FTP access only for me, but I have UkrTelecom and the additional service is ordered by DDNS. You can, of course, write all the network subpatterns in the file, but it becomes very large. I need to figure out what to write in ftpaccess that would only let me in. Can anyone come across, tell me. I've searched the internet and can't find it.
Thanks for any help.

Answer 1

authorized ftp? login and password, and go even from Mars ...