Abstract
Emerging concepts like Industrial Internet of Things (IIOT) and Industrie 4.0 require Industrial Automation and Control Systems (IACS) to be connected via networks and even to the Internet. These connections raise the importance of security for those devices enormously. Security testing for IACS aims at searching for vulnerabilities which can be utilized by attackers from the network. Once discovered, those gaps should be closed with patches before they can get exploited. Different tools utilized for this kind of security testing are dealing with network protocols. In practice, they suffer from peculiarities being present in common industrial automation protocols like OPC UA and Profinet IO. This paper tries to improve the situation by providing an extensive overview of network packet structures and network protocol behavior. Based on this analysis, an example protocol has been developed. The idea behind this artificial network protocol is that tools which are able to handle all the specialties of this protocol, are able to handle every imaginable protocol. Finally, those tools can be used to conduct exhaustive security tests for IACS.