J
I have a device which has embedded web-server as well as modbus/tcp interface. I want to protect this device with firewall, so I bought the one really cheap and simple to play with. I want to access this device through the firewall (currently it's completely open) but once the communcation is initated java program uploaded to my PC tries to negotiate with the device - with modbus/tcp and fails. Is it possible that the firewall thinks that modbus/tcp frame is malicious and drops them even though the negotiation port is not closed?