UFW Firewall

  1. Install with:
    apt update
sudo apt install ufw
  2. Check preset profiles and allow necessary services as root:
    sudo ufw app list
sudo ufw default allow outgoing
sudo ufw allow http/tcp
sudo ufw allow https
sudo ufw allow 3493 # NUT
sudo ufw allow <custom port>/tcp # FTP
sudo ufw allow <custom port:range> # FTP passive port range/tcp
  3. Enable firewall and check status:
    ufw enable
sudo ufw status
  4. Remove firewall rule:
    sudo ufw status numbered
sudo ufw delete <rule number>