modbus traffic not going through IPSec tunnel although PING works.

Question

Hello everyone,
How do I get modbus traffic over IPSec tunnel?
I can ping over the tunnel no problem.

Using modpoll utility I get:
"Protocol configuration: MODBUS/TCP, FC3
Slave configuration...: address = 1, start reference = 1, count = 1
Communication.........: 192.168.71.10, port 502, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, output (holding) register table

Can't reach server/slave! Check TCP/IP and firewall settings."

The Digi firewall is disabled.
Any ideas?

Answer 1

If you have ping working then you probably have a firewall issue on the head end side but that is just an educated guess.

To fault this, you should use the trace function to confirm that the ethernet side of the digi is sending and receiving the request/response. You can also then trace the ethernet side of the "ppp" instance to confirm the response is being encrypted and returned.


Nicholas Wilson
Your IoT
https://www.YourIoT.com.au