
221Intrusion Detection for SCADA Systems
to the hop count between these sources and destinations. The NPDU describes the BMS system, and
it is very dependent on the network topology. Hence, the values of the NPDU eld reect the type
of the network topology. The APDU denes the type of the request or reply and whether they are
conrmed or unconrmed in addition to the service attached with this request/reply and the control
values, such as pressure and temperature.
9.4.4 detection SySteM analySiS for no attack caSe
In this section, we study the behavior of our detection system without applying any type of attack in
order to examine false posi ...