The coordinated functioning of several infrastructures suchas electric systems, power systems, transportation systems, fresh food distribution chains, Gas-ducts, oil pipelines laiesthe foundation of morden socitey. These infrastructuresare really complex huge systems with multiple heteorgenous subsystems in which computation, communication, and controlare coupled with physical dynamics. Identifying, understanding and protecting these critical infrastructures are crucial tasks to be pursued by the scientific community at both the academicand applied levels. Most infrastructuresare indeed hybrid systems in which heteorgenous subsystems coexist and interact with each other.It is natural to apply the network science paradigm to model and analyze critical infrastructures.Different from the traditional simple networks, subsystem intereactions and function depedences of critical infrastructureshave lead to a concept of ‘‘Networks of Networks’’.

The multiple-netowork feature promotes the study of multilayer networks, which paies more attention on structure characterstic of multiple networks.On the other hand,such systems are volunable to malicious attacksas theinterdependenciesof infrastructureswill increase the risk of casecade failure and cyber attackes(e.g., DoS attacks, false data injection attacks and replay attacks etc.), which forces us to rethink the conrol problem in light of security concerns. Although there are fruitful results from computer sciences to address network secure, they cannot address the control security issues due to the absence of knowledge on control internals, and also cannot adapt well to the control requirements.