  The concepts of Internet of Things (IoT) and Cyber Physical Systems (CPS) are
closely related to each other. IoT is often used to refer to small
interconnected devices like those in smart home while CPS often refers to large
interconnected devices like industry machines and smart cars. In this paper, we
present a unified view of IoT and CPS: from the perspective of network
architecture, IoT and CPS are similar. In both IoT and CPS,
networking/communication modules are attached to original dumb things so that
those dumb things become smart and can be integrated into cyber space. If
needed, actuators can also be integrated with a thing so as to control the
thing. With this unified view, we can perform risk assessment of an IoT/CPS
system from six factors, hardware, networking, operating system (OS), software,
data and human. To illustrate the use of such risk analysis framework, we
analyze an air quality monitoring network, smart home using smart plugs and
building automation system (BAS). We also discuss challenges such as cost and
secure OS in IoT security.
