ban hosts that cause multiple authentication errors

 Fail2ban monitors log files (e.g. /var/log/auth.log,
 /var/log/apache/access.log) and temporarily or persistently bans
 failure-prone addresses by updating existing firewall rules. Fail2ban
 allows easy specification of different actions to be taken such as to ban
 an IP using iptables or hostsdeny rules, or simply to send a notification
 email.
 .
 By default, it comes with filter expressions for various services
 (sshd, apache, proftpd, sasl, etc.) but configuration can be
 easily extended for monitoring any other text file. All filters and
 actions are given in the config files, thus fail2ban can be adopted
 to be used with a variety of files and firewalls. Following recommends
 are listed:
 .
  - iptables/nftables -- default installation uses iptables for banning.
    nftables is also supported. You most probably need it
  - whois -- used by a number of *mail-whois* actions to send notification
    emails with whois information about attacker hosts. Unless you will use
    those you don't need whois
  - python3-pyinotify -- unless you monitor services logs via systemd, you
    need pyinotify for efficient monitoring for log files changes