Cyber physical systems consists a crowd of computing nodes and the material processes associated with it. The objects correlated with these embedded things may embrace of a central processor, sensor and actuator units annotated around various communication devices. These device capabilities with least human intercession are proficient to seize data from various environments that requires “smartness” and hence IoT can be briefed as Smart devices centre. As massive numbers of devices are coupled with IoT, there exists a colossal take up on the protocol standards wide with various communication capabilities. This is in regard of assuring the security standard diffusion between the objects of data transfer and the terminal it reaches to. The heterogeneity between these objects and application platforms is an encumbrance to the developers for implementing the architecture for particular services. Cloud platforms rescue the situation by storing, computing and visualizing data before transforming them into meaningful information. Botnets or Zombie army is a malware that takes control of a computer in which the attacker can squeeze into the network raising threat to the authenticity of devices and access to networks. Phishing and Spamming attacks are causing a severity to networks through insecure connections. The security facet of IoT has to be redefined in terms of confidentiality so that the end user is guaranteed with secure data and data integrity can be retained. Various technologies lay around Transport layer Security (TLS) that helps the network to maintain its privacy. This chapter first discusses the Constrained Application Protocol (COAP) associated with 6LoWPAN network. A 6LoWPAN network is a cluster of LoWPAN networks which comprises of low cost and low power devices. These networks are bearing passive and active attacks that affect the network’s confidentiality causing its performance malfunction. In passive attacks, the attacker is abiding to spy on network and steal the confidential information. Denial of Service attacks make obscure scene to network causing performance degradation to the network; active attack is a label in the case. Next focus is to discuss on the protocol stack that congregate the standardized notations of the ISO/OSI and TCP/IP stacks. The stack is being dealt in industrial applications and then turn into de-facto standard that saturates the existing IoT growth on wireless nodes. Next we confer about the IPv6 Routing Protocol (RPL) for Low-Power and Lossy Networks. It consists of constrained nodes with low processing power which are typically unstable with low packet delivery rates. They are mainly battery controlled devices consuming less memory and energy; their traffic patterns are generally multipoint or multipoint-to-point and hence requires compromises with thousand of interconnected nodes. It integrates the method of multipoint-to-point traffic from devices inside the LLN towards a central control point and the point-to-multipoint traffic from the central control point to the devices inside the LLN. Following this, Time-based secure key generation approach that convolutes the local key generation at the both transmission ends is discussed. A time stamp is put up on the local transmitter. The validity of the secure keys is limited to a time interval and the reply attacks comprised on valid messages are removed. The key generation process is a procedure performed separately by both communication objects. Finally, the chapter perceive with Cognitive Security in IoT devices in which the arena uses authentication through well defined user properties and patterns. Cognitive solutions in wireless security become concrete, since conventional static security is meant with lack of privacy. The user is able to learn continuously from the network and machine learning approaches can be incessantly applied with the stipulated security problems. The mediators in the capillary network can monitor the parameters related with Cognitive security standard and raise the security with time based solutions. © Springer International Publishing AG 2018.