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Institute
BTU
Virtual Private Components
(2002)
The increasing use of wireless networks has raised the desire to have not only a stable and good quality access to the network, but also to seamlessly change the network when moving. Various handover algorithms have been proposed to handle this situation. Unfortunately, many of these handover algorithms have only been evaluated by simulations. They do not take the wide range of mobile devices with varying system parameters into account. For the practical deployment, handover algorithms are required that adapt to various device parameters and network characteristics. In this paper we present a fuzzy-based vertical handover decision algorithm which adjusts itself to the given device and network capabilities. Starting with a discussion of handover requirements we present the algorithm and describe how it is activated in the handover process. Finally we present several experiments which evaluate the accuracy of the handover decision, the quality of service guarantees for the application, and the resource consumption.
This book constitutes the refereed proceedings of the 38th Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2012, held in Špindlerův Mlýn, Czech Republic, in January 2012.
The 43 revised papers presented in this volume were carefully reviewed and selected from 121 submissions. The book also contains 11 invited talks, 10 of which are in full-paper length. The contributions are organized in topical sections named: foundations of computer science; software and Web engineering; cryptography, security, and verification; and artificial intelligence.
The increasing mobility of Internet users and the growing need to collaborate with staff travelling on business belong to the key characteristics of the future Internet. Mobile collaborative applications require novel schemes for group communication that actively support collaborations in wireless scenarios. An intrinsic problem of collaborations in wireless scenarios is the temporary connection loss with the group due to user mobility and network issues. Existing group communication protocols do not sufficiently support this situation. In this paper, we present a new peer-to-peer group communication protocol, called Moversight, that was specifically designed to support closed group cooperation in mobile environments with varying churn rates. It applies a new group communication paradigm, called mobile optimistic virtual synchrony, to handle churn-related peer failures. It enhances the virtual synchrony paradigm for mobile scenarios. The paper introduces the paradigm and describes the main protocol features of Moversight. Finally we present simulation results to demonstrate the applicability of the protocol.
In this paper we propose a novel software-defined networking architecture for enterprise wireless local area networks (WLANs). The goal is to build a framework that exposes tools and methods for a centralized processing of IEEE 802.11 frames. In our architecture all management tasks, including beaconing, client authentication and association, are performed by the central controller instead of the distributed wireless access points as in traditional networks. The generated frames are tunneled to lightweight wireless access points (APs) or thin APs that perform the media access and radio frequency (RF) conversion. Agents executed on thin APs allow scheduling of simple tasks like traffic filtering for local execution. Additionally, the agents provide functions found in modern WLAN chipsets, such as precise frame transmit timings or RF spectrum analysis to the controller. Our architecture allows to delegate computationally intensive tasks to a central instance with enough processing power. Thus, it is best suited for devices with limited resources that we use as thin APs. We present applications that can be built using our framework, e.g., client geolocalization or energy consumption optimization. Finally we evaluate the performance of our architecture in a testbed using COTS devices with open-source software.
Firewalls for the Web 2.0
(2016)
The widespread use of Web 2.0 technologies yields an increasing threat potential for users and related systems. Modern web applications and online services are nowadays based on Web 2.0 technologies, such as JavaScript and AJAX, and thus on the execution of active content in the browsers of the users. Firewalls are a common practice to securely connecting to the internet. In this paper, we propose a novel perimeter firewall architecture for web applications that addresses the entire process chain starting from the data transfer with HTTP via the analysis of manipulated web documents to the extraction and analysis of active contents. The basic idea is to allow only a restricted set of web applications to pass the firewall based on a model of their HTML and JavaScript structure. We evaluate the capability of the resulting models for identifying the underlying web applications and their ability to ward off additional malicious inputs.
This report documents the program and the outcomes of Dagstuhl Seminar 16361 "Network Attack Detection and Defense: Security Challenges and Opportunities of Software-Defined Networking". Software-defined networking (SDN) has attracted a great attention both in industry and academia since the beginning of the decade. This attention keeps undiminished. Security-related aspects of software-defined networking have only been considered more recently. Opinions differ widely. The main objective of the seminar was to discuss the various contrary facets of SDN security. The seminar continued the series of Dagstuhl events Network Attack Detection and Defense held in 2008, 2012, and 2014. The objectives of the seminar were threefold, namely (1) to discuss the security challenges of SDN, (2) to debate strategies to monitor and protect SDN-enabled networks, and (3) to propose methods and strategies to leverage on the flexibility brought by SDN for designing new security mechanisms. At the seminar, which brought together participants from academia and industry, we discussed the advantages and disadvantages of using software-defined networks from the security point of view. We agreed that SDN provides new possibilities to better secure networks, but also offers a number of serious security problems which require further research. The outcome of these discussions and the proposed research directions are presented in this report.
Nowadays, collaborative applications play an increasing role in mobile communications in order to enable cooperation among mobile and/or stationary participants – often using the peer-to-peer (P2P) group communication paradigm. The probability of communication failures increases in mobile environments. As a consequence, frequent leaving and joining of partners can be observed resulting in unstable group topologies. A widely used approach is to divide the group into peer clusters that are fully meshed among each other. In this paper, we propose an application-independent approach for a periodic maintenance of distributed cluster-based group topologies for mobile collaborative applications. The proposed approach also dynamically adapts the overlay structure to changing network conditions. The maintenance strategy can be parametrized by several metrics. It outperforms simple overlay maintenance strategies, such as round-robin, by respecting the resource and computation limitations of mobile devices. The run-time is increased by 10% in the best case compared to LEACH, and by 3 — 5% on average. We describe the approach and evaluate its performance w.r.t. different metrics.
Die zunehmende Digitalisierung auch in Kraftwerken erfordert entsprechend auf diesen Bereich zugeschnittene IT-Sicherheitsverfahren und -technologien. Aktuell stellt die obligatorische Implementierung eines angemessenen Sicherheitsprozesses, wie eines Informationssicherheitsmanagementsystems (ISMS), Betreiber von Erzeugungsanlagen, Energienetzen und anderen kritischen Infrastrukturen vor eine große Herausforderung, denn es gilt, zahlreiche Anforderungen bei der Implementierung zu erfüllen, ohne dass konkrete Methoden zur Umsetzung verfügbar sind. Gleichzeitig ist derEinsatz von IT-Sicherheitstechnologien aus der Bürowelt aufgrund gänzlich anderer Eigenschaften und Anforderungen industrieller Netze kaum möglich. Zur Adressierung dieser Problematik wurden von der Brandenburgischen Technischen Universität Cottbus-Senftenberg (BTU) und der Lausitz Energie Kraftwerke AG (LEAG) innovative Verfahren zur (1) systematischen Bewertung sowie (2) Verbesserung der IT-Sicherheit in hochsensiblen Netzen konzipiert und prototypisch implementiert, die
ein diesem Beitrag mit den zugehörigen Forschungsprojekten vorgestellt werden. Um eine Beeinflussung empfindlicher Kraftwerksanlagen auszuschließen, wurde für alle Methoden ein nichtintrusiver Entwicklungsansatz verfolgt, der sich durch eine passive und vom jeweiligen industriellen Prozess vollständig entkoppelte Analyse auszeichnet und sich daher für einen breiten Einsatz in Netzen mit hohen Verfügbarkeitsanforderungen eignet.
Attack detection in enterprise networks is increasingly faced with large data volumes, in part high data bursts, and heavily fluctuating data flows that often cause arbitrary discarding of data packets in overload situations which can be used by attackers to hide attack activities. Attack detection systems usually configure a comprehensive set of signatures for known vulnerabilities in different operating systems, protocols, and applications. Many of these signatures, however, are not relevant in each context, since certain vulnerabilities have already been eliminated, or the vulnerable applications or operating system versions, respectively, are not installed on the involved systems. In this paper, we present an approach for clustering data flows to assign them to dedicated analysis units that contain only signature sets relevant for the analysis of these flows. We discuss the performance of this clustering and show how it can be used in practice to improve the efficiency of an analysis pipeline.
Attack and Fault Detection in Process Control Communication Using Unsupervised Machine Learning
(2018)
This report documents the program and the outcomes of Dagstuhl Seminar 14292 “Network Attack Detection and Defense: Securing Industrial Control Systems for Critical Infrastructures”. The main objective of the seminar was to discuss new approaches and ideas for securing
industrial control systems. It is the sequel of several previous Dagstuhl seminars: (1) the series “Network Attack Detection and Defense” held in 2008 and 2012, and (2) the Dagstuhl seminar “Securing Critical Infrastructures from Targeted Attacks”, held in 2012. At the seminar, which
brought together members from academia an industry, appropriate methods for detecting attacks on industrial control systems (ICSs) and for limiting the impact on the physical components were considered. A central question was whether and how reactive security mechanisms can be
made more ICS- and process-aware. To some extent it seems possible to adopt existing security approaches from other areas (e. g., conventional networks, embedded systems, or sensor networks). The main question is whether adopting these approaches is sufficient to reach the desired level
of security for ICSs. Detecting attacks to the physical components and appropriate reactions to attacks are new aspects that need to be considered as well. The main result of the seminar is a list of recommendations for future directions in ICS security that is presented in this report.
Cooperation and interactions of mobile users is a characteristic feature of mobile collaborative applications. The users are located in different mobile communication networks or move in or among them, respectively. This requires horizontal and vertical handovers. The latter is required when the networks use different network technologies. Usually each mobile device independently chooses the most appropriate network for its purposes to switch to. In group-oriented applications this may lead to an uncoordinated network selection and as consequence to increased energy consumption. In this paper, we present a distributed vertical handover decision algorithm that coordinates the selection of the network among the mobile devices in order to ensure an optimal quality of service for the collaborative application and a low energy consumption of the involved mobile devices. The network selection is based on the calculation of a group benefit for each alternative network using the Simple Additive Weighting (SAW) algorithm. The feasibility of the algorithm is evaluated regarding varying group sizes and resource requirements.
Due to demographic changes in developed industrial countries and a better medical care system, the number of elderly people who still live in their home environment is rapidly growing because there they feel more comfortable and independent as in a clinical environment or in a residential care home. The elderly often live alone and receive only irregular visits. Due to impaired physical skills the probability of falls significantly increases. The detection of falls is a crucial aspect in the care of elderly. Falls are often detected very late with severe consequential damages. There are existing approaches for automatic fall detection. They usually deploy special external devices. Elderly people often do not accept these devices because they expose their frailty. In this paper, we present a location-independent fall detection method implemented as a smartphone application for an inconspicuous use in nearly every situation of the daily life. The difficulty of our approach is in the low resolution range of integrated acceleration sensors and the limited energy supply of the smartphone. As solution, we apply a modular threshold-based algorithm which uses the acceleration sensor with moderate energy consumption. Its fall detection rate is in the average of current relevant research.
Potentials of Using One-class SVM for Detecting Protocol-specific Anomalies in Industrial Networks
(2015)
Modern automation is measured in terms of interoperability and easy administration. Introducing technology focussing on these criteria, however, induce new security risks to existing and future automation installations. Current security approaches in automation do not keep pace with the rising security challenges. Prevalent in automation is the use of access control to protect the system from malicious activity, such as extern attacks. Means to inspect the automation traffic to identify attacks that already have overcome access control or are initiated from inside the automation system are not available, yet. For filling this gap, we investigate in the application of intrusion detection techniques on industrial automation. In this paper, we present the current state of an intrusion detection system tailored to the analysis of operation down to traffic between automation devices on field layer.
Current developments in digitization and industry 4.0 bear new challenges for automation systems. In order to enable interoperability and vertical integration of corporate management systems, these networks have evolved from formerly proprietary solutions to the application of Ethernet-based communication and internet standards. This development is accompanied by an increase in the number of threats. Although the most critical IT protection objective for automation systems is availability, usually no security mechanisms have been integrated into automation protocols. Also Ethernet offers no protection by design for these protocols. One of the most popular real-time protocols for industrial applications is Profinet IO. In this paper, we describe a Denial-of-Service attack on Profinet IO that exploits a vulnerability in the Discovery and Basic Configuration Protocol (DCP) which interrupts the Application Relationship between an IO Controller and an IO Device, and thus prevents the system from being repaired by the operator. The attack combines port stealing with the sending of forged DCP packets and causes a system downtime, which in affected production networks probably lead to a serious financial damage and, in case of critical infrastructures, even represents a high risk for the supply of society. We demonstrate the practical feasibility of the attack using realistic hardware and scenarios and discuss its significance for also other setups.
Low-rate and low-power wireless communications are still the main drivers for innovative industrial automation and the Internet of Things (IoT). Physical mobility is one of the most important challenges for them. Common wireless technologies and protocols, e.g., WirelessHART and ISA100.11a Wireless for industrial process plants, ZigBee for building automation, or 6LoWPAN and 6TiSCH in context of the IoT, are based on the IEEE 802.15.4 standard. Event-based simulation is the method of choice for analyzing network protocols and algorithmic applications of such distributed sensor applications. Performance measurements and holistic evaluations, however, are greatly influenced by the underlying hardware resources, physical layer protocols, and radio channel conditions, which are usually not considered or highly abstracted in network simulations. In this paper we present SEmulate, a hybrid system for seamless (network) simulation and hardware-based emulation for wireless sensor networks based on the IEEE 802.15.4 protocol standard, which takes the hardware aspects into account by applying an Hardware-in-the-Loop (HIL) approach.
Consistency Support for a Decentralized Management in Closed Multiparty Conferences Using SIP
(2003)
Evaluation of Well-Known Protocol Implementation Techniques for Application in Wireless Networks
(2001)
Protocol Engineering
(2012)