## 3 Related Work
Additionally, while the authors present an example policy and discuss the use of additional options, no real specification is given, while the Rule Packages in this approach are formally specified using the JSON schema, and so is the provider interface. Similar to the approaches in [17; 60], they divide the home network into segments for trusted and untrusted devices that might, however, hinder the local device discovery or communication. In [43], [PERSON] et al. present their idea of restricting network communication inside as well as leaving the local network to the minimum that is needed to preserve the functionality of a device. Similar to [24; 25] they also provide an example of rules that could be fetched from an external provider but do not provide a formal definition of the rule format. However, while they emphasise the importance of communication control inside the local network, they miss the opportunity to detail this concept, and the authors also did not implement their approach. [PERSON] et al. propose novel network filtering-based approach _Bark_[26]. The approach offers fine-grained access control policies, which are formulated using a format that is inspired by natural language constructs. While those rules make it possible to control both remote and local communication according to the user's needs, formulating them can still be too hard for a non-technician. For example, it still requires the user to know what interactions a device really needs in order to work properly. In addition to considering different approaches to applying filtering to the Smart Home, we also see the need to add filtering mechanisms that are used in smart cars to this section, as they are inherently a special case of IoT devices. Today's cars, self-driving or not, exchange information with the outside at least over a standardised interface: the On-Board Diagnosis interface (ODB-II, or ODB for short). This interface enables reading a car's speed, revolutions per minute, and other data. The USA mandated this interface for all new cars starting in 1996, and EU regulations [61] required it for gasoline cars from 2001 and diesel cars from 2004. For information transfer outside the smart car, a small portable device called a _Dongle_, is usually facilitated and connected using the OBD interface. This information comes from so-called Electronic Control Units (ECUs). An ECU is a computerised system within the vehicle dedicated to a function which communicates via a network called CAN (Controller Area Network), or CAN-BUS [62; 63]. Dongles' security is analysed by [PERSON] et al. in [64], in order to provide a comprehensive vulnerability analysis of 77 On-Board-Diagnosis (OBD-II) dongles. In the paper, the authors propose an automated tool called DongleScope to perform an analysis and test the dongles. Moreover, the authors identify and define different types of possible vulnerabilities. In [65], [PERSON] et al. give an overview of various security vulnerabilities and points of entry for malicious entities in vehicular systems. Several works are dedicated to researching information that can be gained from a car and how it can influence privacy [66; 67; 68; 69]. All works describe how to monitor cars, predict the condition of the internal hardware, detect driving habits, and discover different anomalies. [PERSON] et al. define and explain eight security requirements and five safety requirements for vehicle systems [70]. They also describe how existing systems and solutions can be used to fulfil these requirements. Furthermore, the authors explain in detail what safety concepts are to be pursued in vehicle systems and possible problems or limitations that may arise. In [71], [PERSON] et al. show the need to examine and modify already existing security vehicle systems. The authors prove that the Intrusion Detection System does not fully protect cars from intruders, even though this system is one of the newer ones in vehicle safety. They conclude that improvements need to be made to minimise the risk of attacks.