Abstract

Abstract
With continuous technological advancement, multihomed devices are becoming common. They can connect simultaneously to multiple networks through different interfaces. However, since TCP sessions are bound to one interface per device, it hampers applications from taking advantage of all the available connected networks. This has been solved by MPTCP, introduced as a seamless extension to TCP, allowing more reliable sessions and enhanced throughput. However, MPTCP comes with an inherent risk, as it becomes easier to fragment attacks towards evading NIDS. This paper presents a study of how MPTCP can be used to evade NIDS through simple cross-path attacks. It also introduces tools to facilitate assessing MPTCP-based services in diverse network topologies using an emulation environment. Finally, a new solution is proposed to prevent cross-path attacks through uncoordinated networks. This solution consists of a hostlevel plugin that allows MPTCP sessions only through trusted networks, even in the presence of a NAT.

Abstract

Abstract
Physically-based synthesis of high quality imagery, including global illumination light transport phenomena, results in a significant workload, which makes interactive rendering a very challenging task. We propose a VPL-based ray tracing approach that runs entirely in the GPU and achieves interactive frame rates while handling global illumination light transport phenomena. This approach is based on clustering both shading points and VPLs and computing visibility only among clusters' representatives. A new massively parallel K-means clustering algorithm, enables efficient execution in the GPU. Rendering artifacts, that could result from the piecewise constant approximation of the VPLs/shading points visibility function introduced by the clustering, are smoothed away by resorting to an innovative approach based on fuzzy clustering and weighted interpolation of the visibility function. The effectiveness of the proposed approach is experimentally verified for a collection of scenes, with frame rates larger than 3 fps and up to 25 fps being demonstrated.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract

Abstract
This article proposes a Markov Chain Monte Carlo (MCMC) rendering algorithm based on a family of guided transition kernels. The kernels exploit properties of ensembles of light transport paths, which are distributed according to the lighting in the scene, and utilize this information to make informed decisions for guiding local path sampling. Critically, our approach does not require caching distributions in world space, saving time and memory, yet it is able to make guided sampling decisions based on whole paths. We show how this can be implemented efficiently by organizing the paths in each ensemble and designing transition kernels for MCMC rendering based on a carefully chosen subset of paths from the ensemble. This algorithm is easy to parallelize and leads to improvements in variance when rendering a variety of scenes.