# Defense and Security Mechanisms in the Internet of Things: A Review
## 1 Introduction
### Motivations and Contributions  
Technology is a part of our life. We utilise a range of sophisticated technologies that primarily enhance our daily lives while facilitating the transfer of substantial volumes of data. Frequently, the transmitted communications include confidential information about users' devices. Thus, data protection is an essential part of intelligent systems' functioning. Users require the endorsement of safety while using technical facilities, thereby ensuring the protection of human life in the real and virtual world.  
Malicious users in IoT environments expose several stages of the communication process to security vulnerabilities. For instance, these users attempt to intercept data and subsequently exploit it. As IoT technology moves forward, so do the methods used to attack it. We must keep reviewing and updating our defense and security measures regularly. Appropriately chosen methods will undoubtedly enhance the security level of connected devices. Thus, this review provides an overview of existing defense and security mechanisms in IoT environments, including Intrusion Detection Systems and Intrusion Prevention Systems and security protocols ensuring data security.  
How defense and security systems work in IoT can give readers insight into the latest theory and real-world application developments. In this section, we will shed light on the security problems and weak points IoT devices face when they are part of these networks. We will also discuss the security levels of IDSs, IPSs, and security protocols used in IoTs. We will also focus on the challenges and needs of the newly developed defense mechanisms. The main points of this article are as follows:  
* This paper provides a detailed analysis of the current state of defense and security of the IoT, focusing on protocols and systems such as IDSs, IPSs, and secure communication protocols.
* This paper also outlines the vulnerabilities of the IoT communication mechanisms and the risks of data interception and misuse by adversaries. It highlights the stages where such vulnerabilities are most likely to occur.
* This paper also seeks to explain how cyber-attacks have advanced with the advancement in technology in the area of IoT. Therefore, there is a need to develop and look at the security measures in light of the current technology.
* This paper analyses the efficiency of IDS, IPS, and security protocols to understand the efforts made towards enhancing data protection and the IoT system.
* This article aims at discussing the challenges that would be encountered when implementing security in IoT. The article addresses the practical challenges and requirements for implementing modern defense systems, considering the limitations and prerequisites of recently developed IoT security solutions.
* The article provides a balanced perspective for academic researchers and practitioners in the field by bridging the gap between theoretical insights and practical applications of IoT security.
* The article emphasises the need for regular updates on defense mechanisms and points out future research opportunities, encouraging ongoing advancements in IoT security.  
This research paper presents a deep and thorough survey of IoT security and defensive mechanisms by providing an integrated taxonomy of how security protocols integrate with anomaly detection systems. In contrast to all earlier reviews, this library-focused work gives pertinent detail about the functionality of such mechanisms in real-world IoT scenarios, including strengths and weaknesses.  
This study innovatively contributes a detailed analysis of interdependencies among various attacks and defense approaches. This topic has not been previously covered in reviews. Another aspect of this paper is the emerging concerns in IoT security, like scalability, energy efficiency, and privacy, with possible actionable solutions, such as lightweight protocols and AI-based anomaly detection.