How to stop an attack on a pure-ftpd server?

Question

ubuntu

There is a server on pure-ftpd. Someone is attacking me. After a while, all 50 allowed entries are scored by someone. and when you try to connect - writes 50 users (the maximum) are already logged in, sorry
Anonymous login is prohibited. I tried changing passwords to say: ewjffurhfiurwof93p8u4f. But everything is useless. How can I stop this attack?
pure-ftpd ubuntu desktop

Answer 1

www.fail2ban.org/wiki/index.php/Pure-FTPd
but it's better to remove ftp and use sssh

Answer 2

configure iptables so that access to the port is only from allowed hosts, and does not light up for everyone on the outside.