yum install fail2ban
systemctl enable fail2ban

Конфиги применяются по порядку:

1. /etc/fail2ban/jail.conf
2. /etc/fail2ban/jail.d/*.conf
3. /etc/fail2ban/jail.local
4. /etc/fail2ban/jail.d/*.local

/etc/fail2ban/jail.local

[DEFAULT]
maxretry = 2
destemail = root@localhost
[sshd]
enabled = true