arXiv subjects

Tobias Bühler

Publications and source records attributed to Tobias Bühler.

4 recordsLinked to original sources

arXiv2023

Oscilloscope: Detecting BGP Hijacks in the Data Plane

The lack of security of the Internet routing protocol (BGP) has allowed attackers to divert Internet traffic and consequently perpetrate service disruptions, monetary frauds, and even citizen surveillance for decades. State-of-the-art defenses rely on geo-distributed BGP monitors to detect rogue BGP announcements. As we show, though, attackers can easily evade detection by engineering their announcements. This paper presents Oscilloscope, an approach to accurately detect BGP hijacks by relying on real-time traffic analysis. As hijacks inevitably change the characteristics of the diverted traffic, the key idea is to track these changes in real time and flag them. The main challenge is that "normal" Internet events (e.g., network reconfigurations, link failures, load balancing) also change the underlying traffic characteristics - and they are way more frequent than hijacks. Naive traffic analyses would hence lead to too many false positives. We observe that hijacks typically target a subset of the prefixes announced by Internet service providers and only divert a subset of their traffic. In contrast, normal events lead to more uniform changes across prefixes and traffic. Oscilloscope uses this observation to filter out non-hijack events by checking whether they affect multiple related prefixes or not. Our experimental evaluation demonstrates that Oscilloscope quickly and accurately detects hijacks in realistic traffic traces containing hundreds of events.

cs.NI↗

arXiv2022

pForest: In-Network Inference with Random Forests

When classifying network traffic, a key challenge is deciding when to perform the classification, i.e., after how many packets. Too early, and the decision basis is too thin to classify a flow confidently; too late, and the tardy labeling delays crucial actions (e.g., shutting down an attack) and invests computational resources for too long (e.g., tracking and storing features). Moreover, the optimal decision timing varies across flows. We present pForest, a system for "As Soon As Possible" (ASAP) in-network classification according to supervised machine learning models on top of programmable data planes. pForest automatically classifies each flow as soon as its label is sufficiently established, not sooner, not later. A key challenge behind pForest is finding a strategy for dynamically adapting the features and the classification logic during the lifetime of a flow. pForest solves this problem by: (i) training random forest models tailored to different phases of a flow; and (ii) dynamically switching between these models in real time, on a per-packet basis. pForest models are tuned to fit the constraints of programmable switches (e.g., no floating points, no loops, and limited memory) while providing a high accuracy. We implemented a prototype of pForest in Python (training) and P4 (inference). Our evaluation shows that pForest can classify traffic ASAP for hundreds of thousands of flows, with a classification score that is on-par with software-based solutions.

cs.NI↗

arXiv2020

An Open Platform to Teach How the Internet Practically Works

Each year at ETH Zurich, around 100 students collectively build and operate their very own Internet infrastructure composed of hundreds of routers and dozens of Autonomous Systems (ASes). Their goal? Enabling Internet-wide connectivity. We find this class-wide project to be invaluable in teaching our students how the Internet infrastructure practically works. Among others, our students have a much deeper understanding of Internet operations alongside their pitfalls. Besides students tend to love the project: clearly the fact that all of them need to cooperate for the entire Internet to work is empowering. In this paper, we describe the overall design of our teaching platform, how we use it, and interesting lessons we have learnt over the years. We also make our platform openly available.

cs.NI↗

arXiv2018

Challenges in Network Management of Encrypted Traffic

This paper summarizes the challenges identified at the MAMI Management and Measurement Summit (M3S) for network management with the increased deployment of encrypted traffic based on a set of use cases and deployed techniques (for network monitoring, performance enhancing proxies, firewalling as well as network-supported DDoS protection and migration), and provides recommendations for future use cases and the development of new protocols and mechanisms. In summary, network architecture and protocol design efforts should 1) provide for independent measurability when observations may be contested, 2) support different security associations at different layers, and 3) replace transparent middleboxes with middlebox transparency in order to increase visibility, rebalance control and enable cooperation.

cs.NI↗