There are so many devices that make our life serene and comfortable. The Internet of things (IoT) is one of the most popular technologies. Today IoT applies to all devices. When there are a lot of advantages, there is an equal number of disadvantages. Hackers are the main threats to IoT devices, and they steal data through hacking and leaked it. So, to avoid this there is a usage of so many security protocols and authentication protocols. Here we present the different defence mechanisms based on three categories: physical unclonable function (PUF), algorithm-based, and also, we compare the performance by using some metrics like data anonymity, data privacy, methodology, and threats overcome. The main motivation of this paper is to come up with a clear context about the different methods that provide data anonymity, privacy, and most importantly threats that are overcome. Finally, several methodologies are discussed as also the different types of taxonomy.