Question: Connection to PLC without setting up Gateway in PLC

Teltonika Networks
1

Greetings everyone,

Our situation: We have a customer with numerous automation devices that have a wide range of IP addresses, but the gateways for these devices have not been set up. Normally, we configure the gateway in-house before the devices go online. However, we now have many devices running, and setting up the gateway without power cycling them is not an option.

We are seeking a solution that allows us to avoid setting up the gateway on these devices. We are wondering if this is even possible and, if so, how it can be achieved.

Best regards,

3

Hello,

A gateway is important for PLC to communicate effectively. If your PLC supports DHCP, that’s one option. But if your devices don’t support DHCP or if it’s not possible to use DHCP, you’ll need to find other solutions. For instance, you might use a management tool to configure gateway settings remotely without restarting the devices. This could mean deploying agents or using protocols like SSH or SNMP to manage the devices from afar.

Best regards,

4

While I understand that the gateway is important, I was told yesterday by our Teltonika supplier that it is possible to make it work without setting up the gateway in the PLC.

Right now, without setting up the gateway, I can see the test PLC on the LAN port (scanning the topology) and ping it through the WebUI. I can also ping the RUT241 from the host PC through OpenVPN. In fact, I can ping the LAN port on the RUT241, but I cannot ping the PLC. I assume there is some sort of route that I need to set up to make this work. However, I am quite confident that it is possible.

Best regards,

5

For configuring gateways on numerous automation devices without power cycling, consider these options:

  1. DHCP Configuration: Set up your DHCP server to assign gateway addresses dynamically.
  2. Remote Configuration Tools: Utilize SSH or web interfaces for remote management.
  3. Scripting and Automation: Write scripts or use tools like Ansible for remote configuration.
  4. Network-Level Solutions: Consider routers or network-level setups for centralized gateway management.
6

Hello,

If your devices don’t have a default gateway, they can still talk to each other within the same local network using ARP to find MAC addresses. They can send messages directly to each other. But if they need to talk to devices outside of this network, they need a gateway to guide their messages in the right direction. Maybe the Teltonika supplier had an idea based on your network setup. It’s worth asking him again about the solution he had in mind.

You might also try enabling masquerading on the LAN to WAN zone. This feature uses iptables to change the source IP addresses of outgoing packets to match the IP address of the network interface they’re going through.

Best regards,

7

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