Question Port Forwarding to Local Computer Through Router

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Jun 9, 2022
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So I've got a Digi IX20 router here that is connected to a Linksys modem. Currently, I've got a direct ethernet connection coming from my laptop to the modem, and the modem also has a connection directly to another source(essentially a laptop - 192.168.2.1). I've set up a port forward rule inside of the router such that if I go through ETH1 (192.168.2.10) at port 9018, it will direct me to 192.168.2.1 at port 9018. It's set up this way so that I can test to see if it works, but I think I read somewhere that you cannot port forward over a LAN interface. I tried switching it so that if I go through the router's public IP at port 9018, it would direct me to the same location. For each of these attempts, I get "Connection timed out" when trying to SSH in for port forwarding. Something to note, I can SSH directly to 192.168.2.1 at port 9018 no problem, but the port forwarding doesn't seem to be working. I've also allowed the connections through the Windows Firewall, so that shouldn't be the issue either. I'm extremely new to this concept as well as the terminology behind it, so anything would be greatly appreciated!
 
This connection path (Line diagram) where -----> represents an Ethernet cable?

ISP === (DSL, Coax, Fiber ?) ===> Linksys Modem ---- (1) ---> Laptop #1 and ----(2) ---> Laptop #2 and ---(3) ---> Digi IX20 router

I would expect to see only the Digi router connected to the modem and both laptops (and any other network devices as well) connected to the Digi router.

Feel free to edit and correct my line diagram.

Include the IP addresses assigned to each device.

Which model Linksys modem?

No other wired or wireless devices - correct?

Which laptop is the end destination for the port forwarding requirement?

What is the requirement for port forwarding Port 9018? You mentioned testing - what is being tested?
 
This connection path (Line diagram) where -----> represents an Ethernet cable?

ISP === (DSL, Coax, Fiber ?) ===> Linksys Modem ---- (1) ---> Laptop #1 and ----(2) ---> Laptop #2 and ---(3) ---> Digi IX20 router

I would expect to see only the Digi router connected to the modem and both laptops (and any other network devices as well) connected to the Digi router.

Feel free to edit and correct my line diagram.

Include the IP addresses assigned to each device.

Which model Linksys modem?

No other wired or wireless devices - correct?

Which laptop is the end destination for the port forwarding requirement?

What is the requirement for port forwarding Port 9018? You mentioned testing - what is being tested?

Just to maybe clear up how it is set up, Linksys SD208 8-Port 10/100 modem ------> (1) Laptop #1 (192.168.2.194) AND (2) Laptop #2 (192.168.2.1) AND (3) Digi IX20 Router (192.168.2.11 for http config).

So basically the modem has everything coming in/out of it. Also, I have switched the sign-in IP on the router to be over ETH2 (192.168.2.11) and Laptop #2 to be 192.168.2.1.

The connection from the modem to the router is done through ETH1 and ETH2 on the Digi IX20 currently.
These are the only connections going in/out of each of these devices.

One thing I also forgot to mention is that in the config, port ETH1 on the router's IP is 192.168.2.10 and ETH2 is 192.168.2.11. I have the port forwarding set up right now while I test over a LAN connection that it should only work if I try to SSH using ETH1's IP at port 9018. When I get this working, I'm looking to change the interface to the modem's external IP when this starts working.

The end destination for port forwarding is to be Laptop #2 (192.168.2.1:9018).

So the requirement is that someone from an external network can go to (I believe) the router's external IP at port 9018 and be redirected to Laptop #2 at port 9018. I cannot explicitly disclose the purpose as it is work related, but I am able to directly SSH to 192.168.2.1:9018 and see if I can port forward or not through a direct SSH on laptop #1.

EDIT: I can ping each of these addresses from inside the Digi Router's terminal and from my laptop's command prompt just fine.
 
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This:

"So the requirement is that someone from an external network can go to (I believe) the router's external IP at port 9018 and be redirected to Laptop #2 at port 9018. I cannot explicitly disclose the purpose as it is work related, but I am able to directly SSH to 192.168.2.1:9018 and see if I can port forward or not through a direct SSH on laptop #1. "

Understood and fair enough.

Being that the stated network problem is work related and cannot be disclosed (reasonable) then you need to solicit assistance from your work/company's IT person/staff.

Seeking outside assistance and/or otherwise attempting access from one laptop to another laptop may be contrary to company rules and policies.

There is no way on this end to know what the requirements and circumstances truly are.

Closing thread accordingly.
 
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