The Internet of Things (IoT) is a paradigm that changes the way we should handle security, since possibilities of attack are now more extensive than ever before. IoT devices are employed more and more in various industries having important roles in the everyday life, and, for this reason, both the IoT device manufacturers and those who integrate and deliver IT projects involving IoT devices must take into account the security and confidentiality aspects. Selection of IoT devices, communication protocols, and security mechanisms must be done according to the level of confidentiality of both the data that is transmitted and the data kept on various storage media. Ensuring a higher-than-necessary security level translates into additional operational costs and/or reduced functionality, while a lower-than-necessary security level leads to customers not trusting and not using the device/system. This paper aims to present the main security requirements of an IoT infrastructure, and communication systems and protocols within Smart environments./p>