Internet of Things (IoT) is becoming the most significant computing platform. With recently developed applications such as Smart Transportation, Smart City, Smart Home, IoT technologies are significantly changing our lifestyle. Novel Solutions are essential to protect the IoT systems from the attacks. The objective of the Internet of Things is to provide security and privacy to the users. This paper aims to analyses security challenges resulted from the characteristics of IoT systems. It also discusses the attacks and open problems in different layers. Finally, it analyses the impact of IoT security in smart home appliances.