FrameAssembly
Industrial OT · scada_modbus.fasmFrameAssembly v1.5.1

Simulate Modbus TCP, DNP3, S7comm, BACnet, EtherNet/IP & OPC UA Conduits

You need a safe, synthetic industrial OT capture to verify that your OT firewall permits SCADA register reads while blocking unauthorized Modbus writes or DNP3 breaker operate commands.

What This Capture Builds

Completes a TCP port 502 handshake for Modbus register read/write checks, followed by S7comm DB reads, DNP3 Select/Operate with automatic CRC-16, BACnet, EtherNet/IP, and OPC UA frames.

How to Customize

  1. Define the SCADA HMI workstation and PLC controller.
  2. Run a TCP handshake on port 502 followed by modbus, s7comm, dnp3, bacnet, ethernetip, or opcua statements.
scada_modbus.fasm
host scada_hmi { ip 10.80.20.10 }
host plc_node  { ip 10.80.10.50 }
flow modbus_and_ot_poll(hmi, plc) {
    hmi -> plc tcp syn srcport 50200 dstport 502 wait 1ms
    hmi <- plc tcp syn ack wait 1ms
    hmi -> plc tcp ack wait 1ms
    hmi -> plc modbus read_holding_registers txid 101 unitid 1 addr 40001 count 4 wait 5ms
    hmi <- plc modbus read_holding_registers txid 101 unitid 1 count 4 is_response wait 5ms
    hmi -> plc modbus write_single_register txid 102 unitid 1 addr 40001 value 1500 wait 5ms
    hmi -> plc transport udp dnp3 select src 1 dst 10 group 12 variation 1 wait 2ms
    hmi -> plc transport udp dnp3 operate src 1 dst 10 group 12 variation 1 wait 2ms
    hmi -> plc bacnet read_property invoke_id 10 object_type 0 object_instance 1 property_id 85 wait 2ms
}
compile {
    modbus_and_ot_poll(scada_hmi, plc_node)
}
Local CLI Compile, Inspect & Replay Commands
# Compile the Industrial OT / SCADA conduit capture
frameassembly scada_modbus.fasm -o scada_modbus.pcap

# Inspect Modbus function codes, DNP3 CRC-16 frames, and BACnet properties in tshark
tshark -r scada_modbus.pcap

# Replay across your OT zone firewall or passive ICS sensor SPAN port
sudo tcpreplay -i eth1 scada_modbus.pcap
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