NAT: What Network Address Translation Is and How It Works

NAT (Network Address Translation) lets many devices with private IPs share one public IP to access the internet.

NAT Types

iptables NAT Setup

# Enable IP forwarding
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

# Masquerade (LAN → internet)
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

# Port forwarding (DNAT)
sudo iptables -t nat -A PREROUTING -p tcp --dport 80     -j DNAT --to-destination 192.168.1.10:80