Detection of emergent behavior for internet filtering systems

Network filtering has become an important security issue worldwide. Network filters are designed and put in place to enforce restrictions for a variety of different motives, such as political, social, economical or merely security reasons. Although network filters can be applied to different networks, their main use is for the Internet. However, as is the case with most network security measures, many network filters are bypassed by users and thus are not completely adequate to perform their tasks. This paper approaches the network filtering concepts from a software engineering perspective. The general purpose of this approach is to utilize automated methodologies to analyze the correctness of the requirements of the filtering mechanisms, and to reduce their vulnerability. In order to achieve this, requirements are expressed using scenario-based specifications. The resulting scenarios are then analyzed for unwanted behavior using automated methodology. To demonstrate the effectiveness of this approach, it is applied to the case study of a real-life Internet-filtering system.