NAT router vs. port forwarding

[eparizher]

Could you clarify what is the difference between NAT with port forwarding and firewall port forwarding?
I've got communication BACnet IP through NAT only one way: I can discover BACnet devices on private network (Delta) from JACE with public IP, but I can't discover any MS/TP controllers and JACE itself from ORCAView.

[berg2666]

Is the Orcaview on the same network as the Jace?

[eparizher]

No, ORCAVeiew is behind NAT router in private network. JACE has public IP and connect to the system over Internet.

[D1G]

The two are one in the same. There is no need for port forwarding if you're not using NAT. Port forwarding is only used to allow a private IP to be accessible from the internet on a given port. If you have a public IP behind a firewall you don't need to forward traffic to it you just need to allow traffic to it. 1:1 NAT is essentially just that but with the firewall resolving multiple public IP addresses.

edit: PAT (port address translation) works similar but in reverse, connections must originate from the internal IP but it has the advantage of providing the private IP with a complete end-point map of the connection to the remote machine. From the view point of the external IP the traffic is sourced from the PAT device.

I believe what was meant in your other thread would be to attain an additional public IP for the ORCA server and create a firewall rule to allow traffic to it.

D1G