NAT 1:1 What am I doing wrong?

Hi all,
I´ve been having problems when I try to create a NAT 1:1 betwen a WAN network and one LAN device (PLC) using a RUT200, it seems simple but I cannot reach the device after the configuration. I show you below the images and the custom rule created.

I need to read the memory of the PLC, to show information in a management dashboard in grafana, using nodered, but I cannot reach the device directly because has the IP in the 192.168.1.xx familiy, which is not allowed in out network. Thats why I need the RUT, to NAT the PLC in a allowed IP addres.

Thanks in advance.

Hello,

Thank you for providing the details of your setup. From the first glance, iptables rules look proper. Therefore, in your case, here are a few suggestions and points worth checking or testing:

  1. Enable masquerading on the LAN zone in Network → Firewall → Zones settings.

  2. Confirm that the default gateway on the PLC is set to 192.168.1.100 (the RUT200’s LAN IP). Without this, the PLC won’t know how to route reply traffic back through the RUT200.

  3. It might also be worth configuring a port forwarding rule, allowing traffic from the WAN for the specific 10.77.202.19 allowed IP to the internal IP of the PLC. More information on port forwarding can be found here: RUT200 Firewall - Teltonika Networks Wiki.

Please feel free to test these options and let me know if any of them work for you.

Best regards,

Hi Martynas,
I completely forgot to thank you, I followed your suggestions and the solution was this one:

Confirm that the default gateway on the PLC is set to 192.168.1.100 (the RUT200’s LAN IP). Without this, the PLC won’t know how to route reply traffic back through the RUT200

The PLC didnt have the gateway configured, once I note that, I change the gateway and the RUT started to wokr properly.

Thanks for your help, regards.

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Hello,

Thank you for the update. I’m glad to hear I could help and the issue was resolved! If you need any further assistance, feel free to reach out anytime.

Best regards,

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