What Is Port Triggering Used For on a Router?

Port trigger temporarily opens network ports on a router for incoming data.

Modern routers provide port triggering capabilities, a method for opening incoming data ports for computers connected to a local area network (LAN). Internet-based applications, such as online games and file transfer protocol (FTP) programs, require open port access to send and receive data.

Function

Routers use a network address translation (NAT) firewall to protect a network from unauthorized access over the Internet. The NAT firewall blocks incoming data transmissions by sealing the incoming data ports on the network. Port triggering temporarily opens these data ports when a LAN computer requires unrestricted access to the Internet.

Benefits

Port triggering differs from another method for opening incoming data ports known as port forwarding. With port forwarding, the router leaves the specified data ports open all the time. Port triggering, however, only opens the ports when a computer requests access to them. Also, unlike port forwarding, port triggering does not require LAN computers to have a static network address.

Considerations

You can enable port triggering through the router's configuration software. With port triggering, only one computer at a time can access the open port, whereas port forwarding permits multiple LAN computers to share a single open port.

References

• Port Forward: What is Port Triggering?
• DSL Reports: What is the difference between port forwarding and port triggering?
• Webopedia: Port Triggering