Specific intrusion detection systems (IDSs) are needed to secure modern supervisory control and data acquisition (SCADA) systems due to their architecture, stringent real-time requirements, network traffic features and specific application layer protocols. This lecture aims to contribute to assess the state-of-the-art, identify the open issues and provide an insight for future study areas. To achieve these objectives, we start from the factors that impact the design of dedicated intrusion detection systems in SCADA networks and focus on network-based IDS solutions. We propose a structured evaluation methodology that encompasses detection techniques, protected protocols, implementation tools, test environments and IDS performance. Special attention is focused on assessing implementation maturity as well as the applicability of each surveyed solution in the Future Internet environment. Based on that, we provide a brief description and evaluation of 26 selected research papers, published in the period 2015–2019. Results of our analysis indicate considerable progress regarding the development of machine learning-based detection methods, implementation platforms, and to some extent, sophisticated testbeds. We also identify research gaps and conclude the analysis with a list of the most important directions for further research.