# Install ufw:

apt install ufw

# Set rules back to default:
ufw default deny incoming
ufw default allow outgoing


# Allow ssh:
ufw allow ssh
# or
ufw allow 22

# Enable ufw:
ufw enable

# Disable:
ufw disable

# See rules:
ufw status verbose

# Allow multiple ports: from 6000-6007
ufw allow 6000:6007/tcp
ufw allow 6000:6007/udp

# Allow incoming traffic on a public interface on a specific port:
ufw allow in on eth0 to any port 80

# List rules by number:
ufw status numbered

# Delete rule:
ufw delete 2