sudo apt update && sudo apt upgrade
sudo apt install fail2ban

sudo systemctl enable --now fail2ban
sudo systemctl status fail2ban

sudo vim /etc/fail2ban/jail.local
[DEFAULT]
bantime  = 1h
findtime = 10m
maxretry = 5

[sshd]
enabled = true
port    = ssh
backend = systemd

sudo fail2ban-client -t
sudo systemctl restart fail2ban

sudo fail2ban-client status
sudo fail2ban-client status sshd
sudo fail2ban-client set sshd unbanip 192.168.1.100