Firewall Basics (UFW)

# Enable firewall
sudo ufw enable
sudo ufw disable
sudo ufw status
sudo ufw reload

# Allow by port
sudo ufw allow 22 # SSH
sudo ufw allow 80 # HTTP
sudo ufw allow 443 # HTTPS

# Allow by service
sudo ufw allow ssh
sudo ufw allow http

# Allow from IP
sudo ufw allow from 192.168.1.100

# Allow IP to port
sudo ufw allow from 192.168.1.100 to any port 22

# Deny IP
sudo ufw deny from 203.0.113.100

# Show numbered rules
sudo ufw status numbered

# Delete by number
sudo ufw delete 2

# Delete by specification
sudo ufw delete allow 80

# Port ranges
sudo ufw allow 6000:6007/tcp

# Default policies
sudo ufw default deny incoming
sudo ufw default allow outgoing