When is Port Forwarding not Port Forwarding?

When its a virtual server.  Apparently >.>

If you have multiple servers connected through a single gateway (like a router), how does the router know which server to direct a client’s request to?  We use port forwarding to dissolve this kind of ambiguity.

Step 1: Assign static IPs to the server boxes

In a Linux environment, first we switch our network connection from DHCP to manual.  Then, we pick an IP Address within the gateway’s Subnet Mask, but outside it’s DHCP range.

Generally, these settings are found in the Router's GUI web interface.

The subnet or network mask will be the same as for the router, usually 255.255.255.0, with the gateway address being the IP address of the router.

Step 2: Collect information

You will need to know what the IPs and access ports are for each machine. E.G.

Box 1:  10.2.2.22:30
Box 2:  10.2.2.23:33

Then you must decide on which ports on the router you want to forward to either of these machine/port combinations

|----------------------------------------|
| MACHINE | ROUTER PORT | MACHINE IP/PORT|
|---------|-------------|----------------|
| Box 1   | 10.2.2.1:22 | 10.2.2.22:30   |
| Box 2   | 10.2.2.1:55 | 10.2.2.23:33   |
|----------------------------------------|

Step 3: Set router

For this your router’s documentation will have to guide you, but you already have all the info you need.  Right?  Right??

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