What is Port Forwarding?

Question

Please explain. Thank you.

Answer 1

port forwarding is the act of forwarding a network port from one network node to another. This technique can allow an external user to reach a port on a private IP address from the outside via a NAT-enabled router.

Answer 2

The job of a firewall is to Block all ports from external access, for security reasons.

In essence, port forwarding is "UnBlocking" a specified port, or range of ports that you specify as safe, or trusted, for use by specific programs, or services on your network.

For example, I use various VoIP services.

I have a linksys NAT-Router and behind that my PC and a Linksys ATA VoIP adapter for making VoIP calls.

Before I can reliably use my ATA adapter for making SIP-based VoIP calls, I had to Port Forward, or unblock SIP ports 5060-5063, and RTP ports 16384-16482.  These ports can be "Forwarded" on a permanent basis, or opened on a "triggered" basis, as needed.