## 1 Introduction  
In recent years, Internet of Things (IoT) has become an important topic amongst technology enthusiasts and industries. IoT comprises physical devices such as refrigerators, cars, buildings, health monitoring systems, and many others which are embedded with sensors, actuators, radio frequency identification (RFIDtags, and software. These things are connected to a network (Internet) that enables them to exchange and collect data. IoT has stepped out from its infancy and is on the path of transforming our current understanding of a static Internet to a fully integrated dynamic future Internet [1]. Zigbee, \(Z\)-Wave, 6 LoWPAN, Wi-Fi, GSM/3G/4G/LTE, LoRa, Neul, and Sigfox are all communication technologies used in IoT. Currently, Zigbee is the most used technology in home automation and smart lighting. Zigbee is expected to capture 34% volume share of the home automation and 29% of the smart lighting markets by 2021 with Compound Annual Growth Rate (GACR) of 26% during the period of 2016-2020 [2]. Seeing the fast growth of IoT usage, and Zigbee communication specifically, has sparked the attention of research communities to investigate the security concerns that the IoT industry faces. Securing IoT systems in communication technology has been the concern of many researchers and private companies. Symantec has reported that 52% of health apps connected to wearable devices do not have a privacy policy in place, and 20% of personal information, logins, and passwords are in clear texts [3]. In May 2014, more than 90 people from 19 different countries in connection with \"creepware\" were arrested by the FBI and the police for using internet-connected webcams to spy on people [4]. Many researchers have also found that many cars, hospitals, oil grids, and energy grids connected to an IoT system are vulnerable to cyberattacks [5]. As for Zigbee security concerns, much research and many experiments have been conducted to better understand the security threats to which it is susceptible [6; 7; 8; 9; 10; 11]. Despite the fact that Zigbee protocol could be hacked in many different ways, researchers have agreed that solving the security issues in IoT does not only depend on securing the IoT devices and their communication technology, but also on securing the IoT system as a whole and developing a full solution IoT framework that involves multiple layers of security [12; 13; 14; 15; 16; 17]. The security threats of Zigbee protocol can be divided into Attacks Requiring Key Compromise and Attacks with Unrequired Key Compromise. In order to prevent the acquisition of Zigbee keys by an attacker, the keys must be preloaded out-of-band and cannot be transmitted over the air, and Zigbee devices' physical location should be secured at all times. [PERSON] et al. [18] suggest that the Standard Security level (sending the network key unencrypted over air) should be removed altogether from the Zigbee protocol. Also, default configurations of keys or fallback default keys should not be allowed by the manufacturers. Two existing main attacks of Unrequired Key Compromise are Replay and Denial of Service (DoS). The Frame counter has been added to the frame header at the Network Layer to avoid Replay Attacks [13; 17]. [PERSON] et al. [18] suggested that Replay Attacks could be avoided by configuring the Zigbee protocol in a way to confirm that the sequence number of the newly received packet is at least one number greater than that received previously. DoS Attacks are very common in the attacks related to IoT in general. DoS Attacks can be divided into Insider DoS Attacks and Outsider DoS Attacks. Insider DoS Attacks can happen at the Application Layer (APL) by flooding the network with messages. For example, an attacker can send a load of messages without any delays, which causes the whole network to freeze. Also, Insider DoS Attacks can happen at the Network Layer (NWK) by stopping the forwarded transmission of data between devices that can alter the routing protocol.