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I was troubleshooting a very irregular network interruption between two industrial controllers (AB PLC and a DCS). For those who do not work in industrial autom

by procarch2019 4y ago

I was troubleshooting a very irregular network interruption between two industrial controllers (AB PLC and a DCS). For those who do not work in industrial automation communication between assets is essential and some disruptions can be quite costly depending on the industry/product being made. That can be true of even relatively minimal disruptions. I loaded up an RPi with arch, popped a thumb drive on there and created some startup scripts. Once the RPi booted up it just performed a rolling packet monitor. Once I was alerted about a disruption I went and grabbed the thumb drive. I found a Modbus TCP driver bug. What’s even better is I ended up ‘packaging’ it in an enclosure and was able to utilize it in a lot of scenarios. I’ve been using it over the past 2 years. Edit: in the industrial world equipment like this is not in racks/server rooms. They are usually located in panels that have no external networking (security). When I ‘grabbed’ that means traveling to the site and literally taking the drive.

defrost 4y ago
> Edit: in the industrial world equipment like this is not in racks/server rooms. A rack by any other name . . . :-) TBH I was thinking of not just the trad. IT server room racks but also of cramped radio comms "cupboards" by towers and of production circuit | industrial control access panels / locations in both indoor "warehouse" production and outdoor mineral processing circuits .. Always handy to have a small known general purpose computer with ports, scripts, utilities, etc when you're tracking down the weird bug of the day.
- procarch2019 4y ago
  I’ve been meaning to get a flipper zero, but I would love to see that device with a standard gig Ethernet port. The flexibility would be amazing. PoE for bonus points. However, for ultimate utility I think the next iteration of my packet scraper will be a dual NIC’d SBC so I don’t have to worry about hubs or ‘managed’ switches with port mirroring.
  - liminalsunset 4y ago
    NanoPi R4S is nice and might be of interest to you. The RK3399/OP1 chipset seems well supported by mainline. Only potential drawback is the second GbE LAN is connected using USB3.0 internally on the mainboard. IIRC the XHCI protocol fixes the EHCI (USB2.0) CPU usage polling problem, and the interface can indeed reach close to line speed.

defrost 4y ago

> Edit: in the industrial world equipment like this is not in racks/server rooms. A rack by any other name . . . :-) TBH I was thinking of not just the trad. IT server room racks but also of cramped radio comms "cupboards" by towers and of production circuit | industrial control access panels / locations in both indoor "warehouse" production and outdoor mineral processing circuits .. Always handy to have a small known general purpose computer with ports, scripts, utilities, etc when you're tracking down the weird bug of the day.

procarch2019 4y ago
I’ve been meaning to get a flipper zero, but I would love to see that device with a standard gig Ethernet port. The flexibility would be amazing. PoE for bonus points. However, for ultimate utility I think the next iteration of my packet scraper will be a dual NIC’d SBC so I don’t have to worry about hubs or ‘managed’ switches with port mirroring.
- liminalsunset 4y ago
  NanoPi R4S is nice and might be of interest to you. The RK3399/OP1 chipset seems well supported by mainline. Only potential drawback is the second GbE LAN is connected using USB3.0 internally on the mainboard. IIRC the XHCI protocol fixes the EHCI (USB2.0) CPU usage polling problem, and the interface can indeed reach close to line speed.