IP Forwarding Versus Port Forwarding | Generated by AI
Question: Does IP forwarding in a router mean forwarding an external/public IP address to a computer in its LAN so that the computer can be directly accessed from the internet?
Answer:
Not exactly—there’s an important distinction between IP forwarding (also called IP routing) and port forwarding (or NAT destination mapping).
| Feature | IP Forwarding (Routing) | Port Forwarding / Destination NAT |
|---|---|---|
| What it does | Allows the router to forward packets between different networks (e.g., from WAN to LAN and vice versa) based on destination IP. | Changes the destination IP (and usually port) of incoming packets so they reach a specific internal device. |
| Does the internal device get a real public IP? | Only if you assign it a public IP directly on the device or use 1:1 NAT / IP passthrough. In normal home setups, no. | No. The internal device still has a private IP (192.168.x.x, 10.x.x.x, etc.). Only specific ports are redirected. |
| Typical use case | Enabling routing so devices behind the router can reach the internet (and sometimes be reached if rules allow). | Exposing services (web server, game server, RDP, etc.) on a private device to the internet without giving it a public IP. |
| Common name in home routers | “IP forwarding” or just “routing” is usually always on when NAT is active. | Called “Port forwarding”, “Virtual servers”, “NAT rules”, etc. |
Summary
- IP forwarding alone does not give a computer in your LAN a real external/public IP in most home/SOHO setups. It simply allows the router to route packets between interfaces.
- To make a computer accessible from the internet, you normally need port forwarding (destination NAT) or a 1:1 NAT / DMZ / IP passthrough configuration that actually maps a public IP to the internal device.
- Some routers/ISPs offer a true “IP passthrough” or “bridge” mode where one LAN device gets the real public IP directly; in that case IP forwarding is still happening, but NAT is bypassed for that device.
So in short:
Plain IP forwarding = routing packets.
Making a LAN computer reachable from outside = usually port forwarding or 1:1 NAT, not just “IP forwarding.”
References:
- Wikipedia - Network Address Translation
- Wikipedia - Port Forwarding
- Cisco - Understanding IP Routing