arXiv subjects

Georg Carle

Publications and source records attributed to Georg Carle.

At least 55 records · Page 3Linked to original sources

arXiv2020

Me Love (SYN-)Cookies: SYN Flood Mitigation in Programmable Data Planes

The SYN flood attack is a common attack strategy on the Internet, which tries to overload services with requests leading to a Denial-of-Service (DoS). Highly asymmetric costs for connection setup - putting the main burden on the attackee - make SYN flooding an efficient and popular DoS attack strategy. Abusing the widely used TCP as an attack vector complicates the detection of malicious traffic and its prevention utilizing naive connection blocking strategies. Modern programmable data plane devices are capable of handling traffic in the 10 Gbit/s range without overloading. We discuss how we can harness their performance to defend entire networks against SYN flood attacks. Therefore, we analyze different defense strategies, SYN authentication and SYN cookie, and discuss implementation difficulties when ported to different target data planes: software, network processors, and FPGAs. We provide prototype implementations and performance figures for all three platforms. Further, we fully disclose the artifacts leading to the experiments described in this work.

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arXiv2020

On the Necessity and Design of Coordination Mechanism for Cognitive Autonomous Networks

Cognitive Autonomous Networks (CAN) are promoted to advance Self Organizing Network (SON), replacing rule-based SON Functions (SFs) with Cognitive Functions (CFs), which learn optimal behavior by interacting with the network. As in SON, CFs do encounter conflicts due to overlap in parameters or objectives. However, owing to the non-deterministic behavior of CFs, these conflicts cannot be resolved using rulebased methods and new solutions are required. This paper investigates the CF deployments with and without a coordination mechanism, and proves both heuristically and mathematically that a coordination mechanism is required. Using a two-CF Multi-Agent-System model with the possible types of conflicts, we show that the challenge is a typical bargaining problem, for which the optimal response is the Nash bargaining Solution (NBS). We use NBS to propose a coordination mechanism design that is capable of resolving the conflicts and show via simulations how implementation of the proposed solution is feasible in real life scenario.

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arXiv2020

A Generalized TDoA/ToA Model for ToF Positioning

Many applications require positioning. Time of Flight (ToF) methods calculate distances by measuring the propagation time of signals. We present a novel ToF localization method. Our new approach works infrastructure-less, without pre-defined roles like Anchors or Tags. It generalizes existing synchronization-less Time Difference of Arrival (TDoA) and Time of Arrival (ToA) algorithms. We show how known algorithms can be derived from our new method. A major advantage of our approach is that it provides a comparable or better clock error robustness, i.e. the typical errors of crystal oscillators have negligible impact for TDoA and ToA measurements. We show that our channel usage is for most cases superior compared to the state-of-the art.

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arXiv2020

Clock Error Analysis of Common Time of Flight based Positioning Methods

Today, many applications such as production or rescue settings rely on highly accurate entity positioning. Advanced Time of Flight (ToF) based positioning methods provide highaccuracy localization of entities. A key challenge for ToF based positioning is to synchronize the clocks between the participating entities. This paper summarizes and analyzes ToA and TDoA methods with respect to clock error robustness. The focus is on synchronization-less methods, i.e. methods which reduce the infrastructure requirement significantly. We introduce a unified notation to survey and compare the relevant work from literature. Then we apply a clock error model and compute worst case location-accuracy errors. Our analysis reveals a superior error robustness against clock errors for so called Double-Pulse methods when applied to radio based ToF positioning

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arXiv2019

Next Generation Resilient Cyber-Physical Systems

Cyber-Physical Systems (CPS) consist of distributed engineered environments where the monitoring and surveillance tasks are governed by tightly integrated computing, communication and control technologies. CPS are omnipresent in our everyday life. Hacking and failures of such systems have impact on critical services with potentially significant and lasting consequences. In this paper, we review which requirements a CPS must meet to address the challenges of tomorrow. Two key challenges are understanding and reinforcing the resilience of CPS.

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arXiv2019

5G QoS: Impact of Security Functions on Latency

Network slicing is considered a key enabler to 5th Generation (5G) communication networks. Mobile network operators may deploy network slices -- complete logical networks customized for specific services expecting a certain Quality of Service (QoS). New business models like Network Slice-as-a-Service offerings to customers from vertical industries require negotiated Service Level Agreement (SLA) contracts, and network providers need automated enforcement mechanisms to assure QoS during instantiation and operation of slices. In this paper, we focus on ultra-reliable low-latency communication (URLLC). We propose a software architecture for security functions based on off-the-shelf hardware and open-source software and demonstrate, through a series of measurements, that the strict requirements of URLLC services can be achieved. As a real-world example, we perform our experiments using the intrusion prevention system (IPS) Snort to demonstrate the impact of security functions on latency. Our findings lead to the creation of a model predicting the system load that still meets the URLLC latency requirement. We fully disclose the artifacts presented in this paper including pcap traces, measurement tools, and plotting scripts at https://gallenmu.github.io/low-latency.

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arXiv2019

The Case for Writing Network Drivers in High-Level Programming Languages

Drivers are written in C or restricted subsets of C++ on all production-grade server, desktop, and mobile operating systems. They account for 66% of the code in Linux, but 39 out of 40 security bugs related to memory safety found in Linux in 2017 are located in drivers. These bugs could have been prevented by using high-level languages for drivers. We present user space drivers for the Intel ixgbe 10 Gbit/s network cards implemented in Rust, Go, C#, Java, OCaml, Haskell, Swift, JavaScript, and Python written from scratch in idiomatic style for the respective languages. We quantify costs and benefits of using these languages: High-level languages are safer (fewer bugs, more safety checks), but run-time safety checks reduce throughput and garbage collection leads to latency spikes. Out-of-order CPUs mitigate the cost of safety checks: Our Rust driver executes 63% more instructions per packet but is only 4% slower than a reference C implementation. Go's garbage collector keeps latencies below 100 $μ$s even under heavy load. Other languages fare worse, but their unique properties make for an interesting case study. All implementations are available as free and open source at https://github.com/ixy-languages/ixy-languages.

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arXiv2019

User Space Network Drivers

The rise of user space packet processing frameworks like DPDK and netmap makes low-level code more accessible to developers and researchers. Previously, driver code was hidden in the kernel and rarely modified, or even looked at, by developers working at higher layers. These barriers are gone nowadays, yet developers still treat user space drivers as black-boxes magically accelerating applications. We want to change this: every researcher building high-speed network applications should understand the intricacies of the underlying drivers, especially if they impact performance. We present ixy, a user space network driver designed for simplicity and educational purposes to show that fast packet IO is not black magic but careful engineering. ixy focuses on the bare essentials of user space packet processing: a packet forwarder including the whole NIC driver uses less than 1,000 lines of C code. This paper is partially written in tutorial style on the case study of our implementations of drivers for both the Intel 82599 family and for virtual VirtIO NICs. The former allows us to reason about driver and framework performance on a stripped-down implementation to assess individual optimizations in isolation. VirtIO support ensures that everyone can run it in a virtual machine. Our code is available as free and open source under the BSD license at https://github.com/emmericp/ixy

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arXiv2019

Galois Field Arithmetics for Linear Network Coding using AVX512 Instruction Set Extensions

Linear network coding requires arithmetic operations over Galois fields, more specifically over finite extension fields. While coding over GF(2) reduces to simple XOR operations, this field is less preferred for practical applications of random linear network coding due to high chances of linear dependencies and therefore redundant coded packets. Coding over larger fields such as GF(16) and GF(256) does not have that issue, but is significantly slower. SIMD vector extensions of processors such as AVX2 on x86-based systems or NEON on ARM-based devices offer the potential to increase performance by orders of magnitude. In this paper we present an implementation of different algorithms and Galois fields based on the AVX512 instruction set extension and integrate it into the finite field library libmoepgf. We compare the performance of the new implementation to the reference implementation based on AVX2, showing a significant increase in throughput. In addition, we provide a survey of the best possible coding performance offered by a variety of different platforms.

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arXiv2019

Optimally Self-Healing IoT Choreographies

In the industrial Internet of Things domain, applications are moving from the Cloud into the edge, closer to the devices producing and consuming data. This means applications move from the scalable and homogeneous cloud environment into a constrained heterogeneous edge network. Making edge applications reliable enough to fulfill Industrie 4.0 use cases is still an open research challenge. Maintaining operation of an edge system requires advanced management techniques to mitigate the failure of devices. This paper tackles this challenge with a twofold approach: (1) a policy-enabled failure detector that enables adaptable failure detection and (2) an allocation component for the efficient selection of failure mitigation actions. We evaluate the parameters and performance of our failure detection approach and the performance of an energy-efficient allocation technique, and present a vision for a complete system as well as an example use case.

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arXiv2019

Design of a Networked Controller for a Two-Wheeled Inverted Pendulum Robot

The topic of this paper is to use an intuitive model-based approach to design a networked controller for a recent benchmark scenario. The benchmark problem is to remotely control a two-wheeled inverted pendulum robot via W-LAN communication. The robot has to keep a vertical upright position. Incorporating wireless communication in the control loop introduces multiple uncertainties and affects system performance and stability. The proposed networked control scheme employs model predictive techniques and deliberately extends delays in order to make them constant and deterministic. The performance of the resulting networked control system is evaluated experimentally with a predefined benchmarking experiment and is compared to local control involving no delays.

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arXiv2019

DTLS Performance - How Expensive is Security?

Secure communication is an integral feature of many Internet services. The widely deployed TLS protects reliable transport protocols. DTLS extends TLS security services to protocols relying on plain UDP packet transport, such as VoIP or IoT applications. In this paper, we construct a model to determine the performance of generic DTLS-enabled applications. Our model considers basic network characteristics, e.g., number of connections, and the chosen security parameters, e.g., the encryption algorithm in use. Measurements are presented demonstrating the applicability of our model. These experiments are performed using a high-performance DTLS-enabled VPN gateway built on top of the well-established libraries DPDK and OpenSSL. This VPN solution represents the most essential parts of DTLS, creating a DTLS performance baseline. Using this baseline the model can be extended to predict even more complex DTLS protocols besides the measured VPN. Code and measured data used in this paper are publicly available at https://git.io/MoonSec and https://git.io/Sdata.

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arXiv2019

Multi-party authorization and conflict mediation for decentralized configuration management processes

Configuration management in networks with highest security demands must not depend on just one administrator and her device. Otherwise, problems can be caused by mistakes or malicious behavior of this admin, or when her computer got compromised, which allows an attacker to abuse the administrator's far-reaching permissions. Instead, we propose to use a reliable and resilient configuration management process orchestrated by a configuration management system (CMS). This can be achieved by separation of concerns (proposing a configuration vs. authorizing it), employing multi-party authorization (MPA), and enforcing that only authorized configurations can be deployed. This results in a configuration management process that is decentralized on a human, decision-making level, and a technical, device level. However, due to different opinions or adversarial interference, the result of an MPA process can end in a conflict. This raises the question how such conflicts can be mediated in a better way than just employing majority voting, which is insufficient in certain situations. As an alternative, this paper introduces building blocks of customizable conflict mediation strategies which we integrated into our CMS TANCS . The conflict mediation functionality as well as the initial TANCS implementation run on top of the distributed ledger and smart contract framework Hyperledger Fabric which makes all processes resilient and tamper-resistant.

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arXiv2019

Agile Network Access Control in the Container Age

Linux Containers, such as those managed by Docker, are an increasingly popular way to package and deploy complex applications. However, the fundamental security primitive of network access control for a distributed microservice deployment is often ignored or left to the network operations team. High-level application-specific security requirements are not appropriately enforced by low-level network access control lists. Apart from coarse-grained separation of virtual networks, Docker neither supports the application developer to specify nor the network operators to enforce fine-grained network access control between containers. In a fictional story, we follow DevOp engineer Alice through the lifecycle of a web application. From the initial design and software engineering through network operations and automation, we show the task expected of Alice and propose tool-support to help. As a full-stack DevOp, Alice is involved in high-level design decisions as well as low-level network troubleshooting. Focusing on network access control, we demonstrate shortcomings in today's policy management and sketch a tool-supported solution. We survey related academic work and show that many existing tools fail to bridge between the different levels of abstractions a full-stack engineer is operating on. Our toolset is formally verified using Isabell/HOL and is available as Open Source.

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arXiv2019

Data Querying and Access Control for Secure Multiparty Computation

In the Internet of Things and smart environments data, collected from distributed sensors, is typically stored and processed by a central middleware. This allows applications to query the data they need for providing further services. However, centralization of data causes several privacy threats: The middleware becomes a third party which has to be trusted, linkage and correlation of data from different context becomes possible and data subject lose control over their data. Hence, other approaches than centralized processing should be considered. Here, Secure Multiparty Computation is a promising candidate for secure and privacy-preserving computation happening close to the sources of the data. In order to make SMC fit for application in these contexts, we extend SMC to act as a service: We provide elements which allow third parties to query computed data from a group of peers performing SMC. Furthermore, we establish fine-granular access control on the level of individual data queries, yielding data protection of the computed results. By adding measures to inform data sources about requests and the usage of their data, we show how a fully privacy-preserving service can be built on the foundation of SMC.

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arXiv2018

Clusters in the Expanse: Understanding and Unbiasing IPv6 Hitlists

Network measurements are an important tool in understanding the Internet. Due to the expanse of the IPv6 address space, exhaustive scans as in IPv4 are not possible for IPv6. In recent years, several studies have proposed the use of target lists of IPv6 addresses, called IPv6 hitlists. In this paper, we show that addresses in IPv6 hitlists are heavily clustered. We present novel techniques that allow IPv6 hitlists to be pushed from quantity to quality. We perform a longitudinal active measurement study over 6 months, targeting more than 50 M addresses. We develop a rigorous method to detect aliased prefixes, which identifies 1.5 % of our prefixes as aliased, pertaining to about half of our target addresses. Using entropy clustering, we group the entire hitlist into just 6 distinct addressing schemes. Furthermore, we perform client measurements by leveraging crowdsourcing. To encourage reproducibility in network measurement research and to serve as a starting point for future IPv6 studies, we publish source code, analysis tools, and data.

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arXiv2018

The Rise of Certificate Transparency and Its Implications on the Internet Ecosystem

In this paper, we analyze the evolution of Certificate Transparency (CT) over time and explore the implications of exposing certificate DNS names from the perspective of security and privacy. We find that certificates in CT logs have seen exponential growth. Website support for CT has also constantly increased, with now 33% of established connections supporting CT. With the increasing deployment of CT, there are also concerns of information leakage due to all certificates being visible in CT logs. To understand this threat, we introduce a CT honeypot and show that data from CT logs is being used to identify targets for scanning campaigns only minutes after certificate issuance. We present and evaluate a methodology to learn and validate new subdomains from the vast number of domains extracted from CT logged certificates.

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arXiv2018

Leveraging Secure Multiparty Computation in the Internet of Things

Centralized systems in the Internet of Things---be it local middleware or cloud-based services---fail to fundamentally address privacy of the collected data. We propose an architecture featuring secure multiparty computation at its core in order to realize data processing systems which already incorporate support for privacy protection in the architecture.

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