sudo apt update sudo apt install fail2ban sudo systemctl enable fail2ban sudo touch /etc/fail2ban/jail.local
Debian 11
sudo systemctl start fail2ban.service sudo systemctl status fail2ban.service
Debian 12
sudo apt install python3-systemd
sudo nano /etc/fail2ban/jail.conf
[DEFAULT] sshd_backend = systemd
sudo systemctl start fail2ban.service sudo systemctl status fail2ban.service
sudo systemctl status fail2ban.service sudo systemctl restart fail2ban.service sudo fail2ban-client status sshd sudo fail2ban-client set <jail-name> unbanip <ip> sudo fail2ban-client set <jail-name> banip <ip>