Can’t remote access to a computer over the internet

[Teknicianexpertiz]

NoMachine Free Version
Connecting to a physical display
Connecting remotely from a Linux system (Kubuntu 20.04 with KDE Plasma 5.18.5) to a Linux system (Kubuntu 20.04 with KDE Plasma 5.18.5)

Hi,

I was running the 7.4.1 version on a Linux computer I was accessing remotely for months with no issues and a couple days ago the external IP stopped showing up for no apparent reason. So I decided to update (the remote computer) to the latest version 8.4.2 and it didn’t solve the issue. The external IP is not showing up on the Welcome window and the Server status window (as shown in server_status.png)

I followed the instructions on the this page: https://kb.nomachine.com/AR10T01175

But the external IP is not showing also which makes the automatic port mapping failed. (as shown in ports.png)

I also followed the instructions on this page: https://kb.nomachine.com/AR04S01122 (2.4. How to configure the router manually through its administrative interface) after trying to make sure that all these prerequisites checked positive:

1) UPnP or NAT-PMP protocol must be enabled in the router. = Yes
2) Port forwarding must be enabled on the router.  = Yes (as shown in port_forwarding.png)
3) The public IP of the router should be static = Not sure about that one
4) Preferably, try to use external port numbers in the range of 1024-65535. = Yes

And it didn’t solve the issue also.

Any suggestions would be greatly appreciated.

Thank you.

 

 

Attachments:

1. 

   server_status.png
   

2. 

   ports.png
   

3. 

   port_forwarding.png
   

4. 

   server_ports.png
   

[Tom]

Teknicianexpertiz
If you can, try to connect to the NoMachine server from your local network, this will allow us to eliminate the problem on the NoMachine server side.

You need to know your public IP to be able to connect to it. The solution to the dynamic IP address problem can be to use services like noip.com.

You can check your public  IP at whatismyip.com. Check it from the computer you want to connect to (NoMachine server).
 Try connecting from outside via NoMachine to the IP you saw on whatismyip.com and port 24080 if that port hasn’t changed.

There may be several reasons for the external IP not showing up in NoMachine.

Run on NoMachine Server command in the console: traceroute whatismyip.com. If the command is not installed, you can do it with the following command: sudo apt install traceroute. With this command you will be able to check if you are behind a double NAT. 

If the first two hops give local addresses, e.g. 192.168.x.x 10.x.x.x 172.16.x.x -172.31.x.x, it means that your computer you want to connect to is behind double NAT.

Regards,
Tom

[Teknicianexpertiz]

Ok. Thanks for the suggestions, I’ll give them a try and get back to you with the results.

[Teknicianexpertiz]

I was able to connect to the computer from the local network (through 192….). I retrieve the external IP of the computer from whatismyip.com, inserted it in the connection information with port 24080 and I wasn’t able to connect.

I did the traceroute whatismyip.com command on the computer I want to connect to remotely, and only local addresses are showing up. So I guess the computer is behind a double NAT.

[Teknicianexpertiz]

I’m not a network or IT admin so I don’t really know what should be done to resolve the issue from that point. Any suggestions?

Thanks.

[Tom]

Hi Teknicianexpertiz,
run on NoMachine Server command in the console: traceroute whatismyip.com and paste its results on forum.

Remove the last two numbers from all IP addresses e.g. 80.92.83.99 replace with 80.92.x.x

Addresses you don’t have to change
192.168.x.x
10.x.x.x
172.16.x.x – 172.31.x.x

these are private addresses, they do not identify your network.

If you paste something that will not be safe, the moderator will remove it before approving the post.

Regards,
Tom

[Teknicianexpertiz]

Ok. I’ll get back to you with the results.

Thanks.

[Teknicianexpertiz]

Here’s the result of the traceroute command on the remote computer:

traceroute to whatismyip.com (172.67.x.x), 30 hops max, 60 byte packets
_gateway (192.168.2.1)  14.549 ms  14.479 ms  14.421 ms
10.11.18.177 (10.11.18.177)  22.734 ms  25.015 ms  27.483 ms
* * *
64.230.x.x (64.230.x.x)  27.115 ms *  27.670 ms
(142.124.x.x)  27.928 ms  29.266 ms  32.569 ms
(64.230.x.x)  35.941 ms  22.362 ms  22.607 ms
(64.230.x.x)  20.105 ms  19.569 ms  19.777 ms
198.32.x.x (198.32.x.x)  20.129 ms  21.331 ms  21.394 ms
162.158.x.x (162.158.x.x)  24.116 ms  24.278 ms 172.70.112.2 (172.70.x.x) 19.631 ms
172.67.x.x (172.67.x.x)  19.813 ms  19.709 ms  21.057 ms

[Tom]

Hi Teknicianexpertiz,
this unfortunately looks like double NAT.
If you do not have access to the router from 10.11.x.x network, you will not be able to forward the port to your router on the 192.168.2.x network.
Without this, NoMachine will not work.

Can you describe how your network is configured in the place where the computer you want to connect to from the outside is located (NoMachine Server)?
Do you have a router?
Do you have a separate Access Point and is the computer you are trying to connect to (NoMachine Server) connected to it via WiFi?

A solution can be to create a tunnel that will connect the computer to which you want to connect to on the VM on e.g. Amazon AWS. Then the connection that comes to the machine on AWS will be redirected to the NoMachine Server behind the double NAT. Unfortunately, this configuration requires technical knowledge and an account with one of the cloud solutions providers.

Regards,
Tom

[Teknicianexpertiz]

The configuration of the network where’s the remote computer is located is pretty simple, 1 WIFI router with a Cable TV receiver connected (via an ethernet cable) to it so the HD TV can connect directly to the internet. The computer I’m trying to connect to is connected to the internet via WIFI.

The strange thing is, I used to be able to connect remotely to this computer with no issues. I think their ISP changed something in their connection because their internet was off for a couple a days prior of me not being able to connect to the computer anymore.

Other than your solution of creating a tunnel, can they contact their ISP to change their double NAT to a single NAT connection?

Thanks.

[Tom]

Hi Teknicianexpertiz,
I don’t know if such a change will be possible. This is definitely the easiest solution.
When explaining to them what effect you want to achieve, tell them that you need to open a port on your router and forward this port to your local computer.

Regards,
Tom

[Teknicianexpertiz]

Ok. Thanks for the suggestion.

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