Unser Institut beschäftigt sich mit einem breiten Themenspektrum wie Skalierbarkeit, Zuverlässigkeit, Sicherheit und Datenschutz, Selbstorganisation und Beherrschbarkeit von Komplexität in Verteilten Systemen in einer Vielzahl von Einsatzszenarien wie Cloud-Computing oder Fahrzeug-Fahrzeug-Kommunikation.


In der Lehre decken wir das gesamte Spektrum von Rechnernetzen, über verteilte Systeme bis hin zu Sicherheit und Privacy-Schutz ab. Unsere noch offenen Abschlussarbeiten und Projektarbeiten finden Sie auf den entsprechenden Webseiten. Für Prüfungen beachten Sie bitte unsere Hinweise.

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Unsere letzten Publikationen

Köstler, J., Reiser, H.P., Hauck, F.J. and Habiger, G. 2023. Fluidity: location-awareness in replicated state machines. 38th ACM/SIGAPP Symp. on Appl. Comp. – SAC (Mar. 2023). [accepted for publication]
In planetary-scale replication systems, the overall response delay is greatly influenced by the geographical distances between client and server nodes. Current systems define the replica locations statically during startup time. However, the selected locations might be suboptimal for the clients, and the client request origin distribution may change over time, so a different replica placement may provide lower overall request latencies. In this work, we propose a locationaware replicated state machine that is able to adapt the geographic location of its replicas dynamically during runtime to locations geographically closer to client request origins. Our prototype is able to observe emerging optimization potentials and to reduce the overall request latency for the majority of clients by adapting its replica locations to the time-dependent optimum placement during real-world use case evaluations, whereby the absolute performance gain is dependent on the respective usage scenario.
Kargl, F., Erb, B. and Bösch, C. 2023. Defining Privacy. Digital Phenotyping and Mobile Sensing: New Developments in Psychoinformatics. C. Montag and H. Baumeister, eds. Springer International Publishing. 461–463.
Kleber, S. and Kargl, F. 2022. Refining Network Message Segmentation with Principal Component Analysis. Proceedings of the tenth annual IEEE Conference on Communications and Network Security (Austin, TX, USA, Oct. 2022).
Reverse engineering of undocumented protocols is a common task in security analyses of networked services. The communication itself, captured in traffic traces, contains much of the necessary information to perform such a protocol reverse engineering. The comprehension of the format of unknown messages is of particular interest for binary protocols that are not human-readable. One major challenge is to discover probable fields in a message as the basis for further analyses. Given a set of messages, split into segments of bytes by an existing segmenter, we propose a method to refine the approximation of the field inference. We use principle component analysis (PCA) to discover linearly correlated variance between sets of message segments. We relocate the boundaries of the initial coarse segmentation to more accurately match with the true fields. We perform different evaluations of our method to show its benefit for the message format inference and subsequent analysis tasks from literature that depend on the message format. We can achieve a median improvement of the message format accuracy across different real-world protocols by up to 100 %.
Kleber, S., Stute, M., Hollick, M. and Kargl, F. 2022. Network Message Field Type Classification and Recognition for Unknown Binary Protocols. Proceedings of the DSN Workshop on Data-Centric Dependability and Security (Baltimore, Maryland, USA, Jun. 2022).
Reverse engineering of unknown network protocols based on recorded traffic traces enables security analyses and debugging of undocumented network services. In particular for binary protocols, existing approaches (1) lack comprehensive methods to classify or determine the data type of a discovered segment in a message, e.,g., a number, timestamp, or network address, that would allow for a semantic interpretation and (2) have strong assumptions that prevent analysis of lower-layer protocols often found in IoT or mobile systems. In this paper, we propose the first generic method for analyzing unknown messages from binary protocols to reveal the data types in message fields. To this end, we split messages into segments of bytes and use their vector interpretation to calculate similarities. These can be used to create clusters of segments with the same type and, moreover, to recognize specific data types based on the clusters' characteristics. Our extensive evaluation shows that our method provides precise classification in most cases and a data-type-recognition precision of up to 100% at reasonable recall, improving the state-of-the-art by a factor between 1.3 and 3.7 in realistic scenarios. We open-source our implementation to facilitate follow-up works.
Bauer, A., Leznik, M., Iqbal, M.S., Seybold, D., Trubin, I., Erb, B., Domaschka, J. and Jamshidi, P. 2022. SPEC Research — Introducing the Predictive Data Analytics Working Group. Companion of the 2022 ACM/SPEC International Conference on Performance Engineering (Bejing, China, 2022), 13–14.
The research field of data analytics has grown significantly with the increase of gathered and available data. Accordingly, a large number of tools, metrics, and best practices have been proposed to make sense of this vast amount of data. To this end, benchmarking and standardization are needed to understand the proposed approaches better and continuously improve them. For this purpose, numerous associations and committees exist. One of them is SPEC (Standard Performance Evaluation Corporation), a non-profit corporation for the standardization and benchmarking of performance and energy evaluations. This paper gives an overview of the recently established SPEC RG Predictive Data Analytics Working Group. The mission of this group is to foster interaction between industry and academia by contributing research to the standardization and benchmarking of various aspects of data analytics.

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Marion Köhler
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Institut für Verteilte Systeme
Universität Ulm
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89081 Ulm


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