It currently allowed more than 7000 ssh attempts per day in a real case using ClearOS 7.2. where we installed the attack detector app.
See:
https://www.clearos.com/resources/documentation/clearos/content:en_us:7_ug_attack_detector
And see:
https://www.digitalocean.com/community/tutorials/how-to-protect-ssh-with-fail2ban-on-centos-7