Tracking Middleboxes in the Mobile World with TraceboxAndroid

peer reviewedMiddleboxes are largely deployed over cellular networks. It is known that they might disrupt network performance, expose users to security issues, and harm protocols deployability. Further, hardly any network measurements tools for smartphones are able to infer middlebox behaviors, specially if one cannot control both ends of a path. In this paper, we present TraceboxAndroid a proof-of-concept measurement application for Android mobile devices implementing the tracebox algorithm. It aims at diagnosing middlebox-impaired paths by detecting and locating rewriting middleboxes. We analyze a dataset sample to highlight the range of opportunities offered by TraceboxAndroid. We show that TraceboxAndroid can be useful for mobile users as well as for the research community

MUST, SHOULD, DON'T CARE: TCP Conformance in the Wild

Standards govern the SHOULD and MUST requirements for protocol implementers for interoperability. In case of TCP that carries the bulk of the Internets' traffic, these requirements are defined in RFCs. While it is known that not all optional features are implemented and nonconformance exists, one would assume that TCP implementations at least conform to the minimum set of MUST requirements. In this paper, we use Internet-wide scans to show how Internet hosts and paths conform to these basic requirements. We uncover a non-negligible set of hosts and paths that do not adhere to even basic requirements. For example, we observe hosts that do not correctly handle checksums and cases of middlebox interference for TCP options. We identify hosts that drop packets when the urgent pointer is set or simply crash. Our publicly available results highlight that conformance to even fundamental protocol requirements should not be taken for granted but instead checked regularly

Report from the IAB COVID-19 network impacts workshop 2020

The Coronavirus disease (COVID-19) pandemic caused changes in Internet user behavior, particularly during the introduction of initial quarantine and work-from-home arrangements. These behavior changes drove changes in Internet traffic. The Internet Architecture Board (IAB) held a workshop to discuss network impacts of the pandemic on November 9-13, 2020. The workshop was held to convene interested researchers, network operators, network management experts, and Internet technologists to share their experiences. The meeting was held online given the ongoing travel and contact restrictions at that time. Note that this document is a report on the proceedings of the workshop. The views and positions documented in this report are those of the workshop participants and do not necessarily reflect IAB views and positions

Report from the IAB workshop on analyzing IETF data (aid) 2021

The "Show me the numbers: Workshop on Analyzing IETF Data (AID)" workshop was convened by the Internet Architecture Board (IAB) from November 29 to December 2, 2021 and hosted by the IN-SIGHT.it project at the University of Amsterdam; however, it was converted to an onlineonly event. The workshop was organized into two discussion parts with a hackathon activity in between. This report summarizes the workshop's discussion and identifes topics that warrant future work and consideration. Note that this document is a report on the proceedings of the workshop. The views and positions documented in this report are those of the workshop participants and do not necessarily refect IAB views and positions

Impact of small promoter amounts on coke structure in dry reforming of methane over Ni/ZrO2

Coke deposition is one of the main challenges in the commercialisation of dry reforming of methane oversupported Ni catalysts. Besides the coke quantity, the structure of the deposits is also essential for thecatalyst lifetime. Accordingly, in this study, we analysed the effect of Na, K, and Cs promoters on boththese variables over Ni/ZrO2catalysts. Besides blocking the most active coke-forming sites already at lowloading, the promoting effect of the alkali metals is also contributed to by their coke gasification activity.To evaluate the additional impact of the latter, the behaviour of alkali-doped catalysts was compared tothat for Mn-doped catalysts, exclusively featuring the site-blocking promotion mechanism. While theconversion is barely affected by the type of promoter, it has a profound effect on the amount and thecomposition of carbon deposits formed during the reaction. Promoting with K or Mn reduces the cokecontent to a similar degree but with less carbon fibres observed in the case of K. The promotion by Cs andNa results in the lowest coke content. The superior performance of Cs and Na-doped Ni/ZrO2catalysts isattributed to the enhanced coke gasificationviacarbonate species on top of the site blocking effects.ChemE/Inorganic Systems EngineeringChemE/Catalysis EngineeringChemE/Algemee

Le role des forces à longues distances dans la determination de la libération d'énergie cinétique translationnelle. La formation de cations C4H4+ à partir du Benzène et de la Pyridine.

Kinetic energy release distributions (KERDs) for the benzene ion fragmenting into C4H4+ and C2H2 have been recorded by double-focussing mass spectrometry in the metastable energy window and by a retarding field experiment up to an energy of 5 eV above the fragmentation threshold. They are compared with those resulting from the HCN loss reaction from the pyridine ion. Both reactions display a similar variation of the kinetic energy release as a function of the internal energy: the average release is smaller than statistically expected, with a further restriction of the phase-space sampling for the C5H5N+ dissociation. Ab initio calculations of the potential-energy profile have been carried out. They reveal a complicated reaction mechanism, the last step of which consists in the dissociation of a weakly bound ion-quadrupole or ion-dipole complex. The KERDs have been analyzed by the maximum entropy method. The fraction of phase-space effectively sampled by the pair of fragments has been determined and is similar for both dissociations. Both reactions are constrained by the square root of the released kinetic energy, epsilon1/2. This indicates that in the latter stage of the dissociation process, the reaction coordinate is adiabatically decoupled from the bath of the bound degrees of freedom. For the C6H6+ fragmentation, the analysis of the experimental results strongly suggests that, just as for the symmetric interaction potential, the translational motion is confined to a two-dimensional subspace. This dimensionality reduction of the translational phase space is due to the fact that the Hamiltonian of both weakly bound complexes contains a cyclic coordinate