The Internet of Things or "IoT" defines a highly interconnected network of heterogeneous devices where all kinds of communications seem to be possible, even unauthorized ones. As a result, the security requirement for such network becomes critical whilst common standard Internet security protocols are recognized as unusable in this type of networks, particularly due to some classes of IoT devices with constrained resources. The document discusses the applicability and limitations of existing IP-based Internet security protocols and other security protocols used in wireless sensor networks, which are potentially suitable in the context of IoT. The analysis of these protocols is discussed based on a taxonomy focusing on the key distribution mechanism