SSH lockout 60min after 5 brute force attempts in 10min

1. install fail2ban

   $ sudo apt update
   $ sudo apt install fail2ban
   

2. edit configuration

   $ sudo vi /etc/fail2ban/jail.conf
   

   [sshd]
   enabled  = true
   port     = ssh
   maxretry = 5    # 5 attempts not permitted
   findtime = 600  # within 10 minutes
   bantime  = 3600 # ban 1 hour
   logpath  = %(sshd_log)s
   backend  = %(sshd_backend)s
   

3. unban an ip address

   $ sudo fail2ban-client set sshd unbanip IP_ADDRESS