MODBUS/TCP 'Force Listen Mode' Function Code Detection
Info Nessus Network Monitor Plugin ID 7101
SynopsisThe MODBUS/TCP client has sent a MODBUS server a Force Listen Mode request.
DescriptionThe MODBUS/TCP client has sent a MODBUS server a Force Listen Mode request. The Force Listen Mode request, function code 8 (0x08) and subfunction code 4 (0x04), will cause the target server into listen-only mode; i.e., it will not send any responses. This function is typically implemented only in serial devices.