How NAT Applies To Device Servers
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This topic adds no new information; It merely provides an explicit demonstration of what happens when you put a Device Server inside of a LAN, behind a NAT gateway.
Establishing an Inbound Connection
An image is worth a thousand words:
As can be seen above, when you have a DS in a LAN, behind a NAT router, you cannot simply establish a connection from outside. The port isn't mapped anywhere, so the router drops the packet.
There are three solutions for establishing a connection with a DS which is behind a NAT router:
Solution 1: The DS Establishes The Connection
Here, the DS initiates the connection. As covered above, there's no problem in setting up an outbound connection from behind a NAT router. In effect, it looks like this:
Points of attention:
Solution 2: Use Tibbo LinkServer
The Tibbo LinkServer is a product developed to answer this exact need. What if both the remote host and the DS (or multiple Device Servers) are behind a NAT router, and you cannot allow inbound access for either one of them?
In this case, you use a middle man. You need a server in the middle, to which both the remote host and the DS could reach, and 'meet' there. Such a scenario would look like this:
This solution is discussed in detail in the LinkServer user manual. It does require one static IP address, and the purchasing and configuration of a separate product (The LinkServer).
Solution 3: Configure The Router for Inbound Access
It is possible to configure a NAT router so it would allow certain inbound traffic, and would correctly route it to a host within its LAN. This is done using Port Forwarding.