portforward

Port forwarding, also called NAT port mapping, is a networking technique that lets external devices reach services on a private LAN by mapping a router’s public port to an internal IP address and port. It is commonly configured on consumer routers to expose services hosted inside a LAN to the Internet while devices remain behind NAT.

How it works: The router forwards incoming traffic on the chosen external port to the designated internal IP address and port, creating a one-to-one connection between the outside port and the inside service. To maintain reliability, the internal device is often assigned a fixed IP via static addressing or a DHCP reservation.

Common uses include hosting a web or game server, enabling remote desktop access, or reaching CCTV cameras and home automation devices from outside the network. Security considerations are important: opening ports can expose devices to threats, so services should be secured, access restricted where possible, and the internal host’s firewall should be enabled.

If the external IP changes, dynamic DNS can provide a stable hostname for remote access. Variants include port triggering, which creates dynamic mappings in response to outbound connections, and UPnP-based automatic rules. Some routers offer DMZ or bridge modes, which expose an entire internal network to the Internet and carry greater risk. Port forwarding remains a common, though potentially risky, method for enabling external access to services inside a private network.