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Do we have the time for IRM?: service denial attacks and SDN-based defences 我们有时间进行IRM吗?:拒绝服务攻击和基于sdn的防御
Ryan Shah, Shishir Nagaraja
Distributed sensor networks such as IoT deployments generate large quantities of measurement data. Often, the analytics that runs on this data is available as a web service which can be purchased for a fee. A major concern in the analytics ecosystem is ensuring the security of the data. Often, companies offer Information Rights Management (IRM) as a solution to the problem of managing usage and access rights of the data that transits administrative boundaries. IRM enables individuals and corporations to create restricted IoT data, which can have its flow from organisation to individual control - disabling copying, forwarding, and allowing timed expiry. We describe our investigations into this functionality and uncover a weak-spot in the architecture - its dependence upon the accurate global availability of time. We present an amplified denial-of-service attack which attacks time synchronisation and could prevent all the users in an organisation from reading any sort of restricted data until their software has been re-installed and re-configured. We argue that IRM systems built on current technology will be too fragile for businesses to risk widespread use. We also present defences that leverage the capabilities of Software-Defined Networks to apply a simple filter-based approach to detect and isolate attack traffic.
物联网部署等分布式传感器网络会产生大量测量数据。通常,运行在这些数据上的分析可以作为一种web服务提供,可以付费购买。分析生态系统中的一个主要关注点是确保数据的安全性。通常,公司提供信息权限管理(Information Rights Management, IRM)作为管理跨管理边界的数据的使用和访问权限问题的解决方案。IRM使个人和企业能够创建受限制的物联网数据,这些数据可以从组织流向个人控制-禁止复制,转发和允许定时过期。我们描述了我们对该功能的调查,并揭示了架构中的一个弱点——它依赖于准确的全局可用性时间。我们提出了一种放大的拒绝服务攻击,它攻击时间同步,可以阻止组织中的所有用户读取任何类型的受限数据,直到他们的软件被重新安装和配置。我们认为,建立在当前技术基础上的IRM系统过于脆弱,企业无法冒险广泛使用。我们还提出了利用软件定义网络的功能来应用简单的基于过滤器的方法来检测和隔离攻击流量的防御措施。
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引用次数: 0
Building an emulation environment for cyber security analyses of complex networked systems 构建复杂网络系统网络安全仿真分析环境
F. D. Tanasache, Mara Sorella, Silvia Bonomi, Raniero Rapone, Davide Meacci
Computer networks are undergoing a phenomenal growth, driven by the rapidly increasing number of nodes constituting the networks. At the same time, the number of security threats on Internet and intranet networks is constantly growing, and the testing and experimentation of cyber defense solutions requires the availability of separate, test environments that best emulate the complexity of a real system. Such environments support the deployment and monitoring of complex mission-driven network scenarios, thus enabling the study of cyber defense strategies under real and controllable traffic and attack scenarios. In this paper, we propose a methodology that makes use of a combination of techniques of network and security assessment, and the use of cloud technologies to build an emulation environment with adjustable degree of affinity with respect to actual reference networks or planned systems. As a byproduct, starting from a specific study case, we collected a dataset consisting of complete network traces comprising benign and malicious traffic, which is feature-rich and publicly available.
由于构成网络的节点数量迅速增加,计算机网络正经历着惊人的增长。与此同时,Internet和intranet网络上的安全威胁数量不断增长,网络防御解决方案的测试和实验需要可用的独立测试环境,以最好地模拟真实系统的复杂性。这些环境支持复杂任务驱动网络场景的部署和监控,从而研究真实可控的流量和攻击场景下的网络防御策略。在本文中,我们提出了一种方法,该方法利用网络和安全评估技术的组合,并使用云技术来构建相对于实际参考网络或计划系统具有可调亲和度的仿真环境。作为副产品,从一个特定的研究案例开始,我们收集了一个由完整的网络痕迹组成的数据集,包括良性和恶意流量,该数据集功能丰富且公开可用。
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引用次数: 4
On the hardness of the strongly dependent decision problem 强相关决策问题的硬度
M. Biely, Peter Robinson
We present necessary and sufficient conditions for solving the strongly dependent decision (SDD) problem in various distributed systems. Our main contribution is a novel characterization of the SDD problem based on point-set topology. For partially synchronous systems, we show that any algorithm that solves the SDD problem induces a set of executions that is closed with respect to the point-set topology. We also show that the SDD problem is not solvable in the asynchronous system augmented with any arbitrarily strong failure detectors.
给出了解决各种分布式系统中强依赖决策问题的充分必要条件。我们的主要贡献是基于点集拓扑的SDD问题的新颖表征。对于部分同步系统,我们证明了任何解决SDD问题的算法都会引起一组执行,这些执行相对于点集拓扑是封闭的。我们还表明,在具有任意强故障检测器的异步系统中,SDD问题是不可解决的。
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引用次数: 3
Entitling concurrency to smart contracts using optimistic transactional memory 使用乐观事务内存赋予智能合约并发性
Parwat Singh Anjana, S. Kumari, Sathya Peri, Sachin Rathor, Archit Somani
It is commonly believed that blockchain is a revolutionary technology for doing business on the Internet. Blockchain is a decentralized, distributed database or ledger of records. It ensures that the records are tamper-proof but publicly readable. Blockchain platforms such as Ethereum [3] and several others execute complex transactions in blocks through user-defined scripts known as smart contracts. Normally, a block of the chain consists of multiple transactions of smart contracts which are added by a miner. To append a correct block into the blockchain, miners execute these transactions of smart contracts sequentially. Later the validators serially re-execute the smart contract transactions of the block. If the validators agree with final state of the blocks as recorded by the miner, then the block is said to be valid and added to the blockchain using a consensus protocol.
人们普遍认为区块链是在互联网上开展业务的革命性技术。区块链是一种分散的分布式数据库或记录分类账。它确保记录是防篡改的,但公开可读。以太坊等区块链平台[3]和其他几个区块链平台通过用户定义的脚本(称为智能合约)在块中执行复杂的交易。通常,一个区块链由矿工添加的多个智能合约交易组成。为了将正确的区块添加到区块链中,矿工按顺序执行这些智能合约交易。之后,验证者依次重新执行区块的智能合约交易。如果验证者同意矿工记录的区块的最终状态,那么该区块就被认为是有效的,并使用共识协议添加到区块链中。
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引用次数: 3
Session guarantees with raft and hybrid logical clocks 会话保证与筏和混合逻辑时钟
Mohammad Roohitavaf, Jung-Sang Ahn, Woon-Hak Kang, Kun Ren, Gene Zhang, S. Ben-Romdhane, S. Kulkarni
Eventual consistency is a popular consistency model for geo-replicated data stores. Although eventual consistency provides high performance and availability, it can cause anomalies that make programming complex for application developers. Session guarantees can remove some of these anomalies while causing much lower overhead compared with stronger consistency models. In this paper, we provide a protocol for providing session guarantees for NuKV, a key-value store developed for services with very high availability and performance requirements at eBay. NuKV relies on the Raft protocol for replication inside datacenters, and uses eventual consistency for replication among datacenters. We provide modified versions of conventional session guarantees to avoid the problem of slowdown cascades in systems with large numbers of partitions. We also use Hybrid Logical Clocks to eliminate the need for delaying write operations to satisfy session guarantees. Our experiments show that our protocol provides session guarantees with a negligible overhead when compared with eventual consistency.
最终一致性是一种流行的地理复制数据存储一致性模型。尽管最终的一致性提供了高性能和可用性,但它可能导致异常,使应用程序开发人员的编程变得复杂。与更强的一致性模型相比,会话保证可以消除其中的一些异常,同时带来更低的开销。在本文中,我们提供了一个为NuKV提供会话保证的协议,NuKV是为eBay具有非常高可用性和性能要求的服务开发的键值存储。NuKV依赖于Raft协议在数据中心内部进行复制,并使用最终一致性在数据中心之间进行复制。我们提供了常规会话保证的修改版本,以避免在具有大量分区的系统中出现减速级联问题。我们还使用混合逻辑时钟来消除为满足会话保证而延迟写操作的需要。我们的实验表明,与最终一致性相比,我们的协议提供的会话保证开销可以忽略不计。
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引用次数: 6
Benefit of self-stabilizing protocols in eventually consistent key-value stores: a case study 自稳定协议在最终一致的键值存储中的好处:一个案例研究
Duong N. Nguyen, S. Kulkarni, A. Datta
In this paper, we focus on the implementation of distributed programs in using a key-value store where the state of the nodes is stored in a replicated and partitioned data store to improve performance and reliability. Applications of such algorithms occur in weather monitoring, social media, etc. We argue that these applications should be designed to be stabilizing so that they recover from an arbitrary state to a legitimate state. Specifically, if we use a stabilizing algorithm then we can work with more efficient implementations that provide eventual consistency rather than sequential consistency where the data store behaves as if there is just one copy of the data. We find that, although the use of eventual consistency results in consistency violation faults (cvf) where some node executes its action incorrectly because it relies on an older version of the data, the overall performance of the resulting protocol is better. We use experimental analysis to evaluate the expected improvement. We also identify other variations of stabilization that can provide additional guarantees in the presence of eventual consistency. Finally, we note that if the underlying algorithm is not stabilizing, even a single cvf may cause the algorithm to fail completely, thereby making it impossible to benefit from this approach.
在本文中,我们着重于使用键值存储实现分布式程序,其中节点的状态存储在复制和分区的数据存储中,以提高性能和可靠性。这种算法的应用出现在天气监测、社交媒体等领域。我们认为,这些应用程序应该被设计为稳定的,以便它们从任意状态恢复到合法状态。具体来说,如果我们使用稳定算法,那么我们就可以使用更有效的实现,提供最终一致性,而不是数据存储表现为只有一个数据副本的顺序一致性。我们发现,尽管使用最终一致性会导致一致性违反错误(cvf),其中一些节点因为依赖于旧版本的数据而错误地执行其操作,但最终协议的总体性能更好。我们使用实验分析来评估预期的改进。我们还确定了稳定的其他变化,可以在最终一致性的存在下提供额外的保证。最后,我们注意到,如果底层算法不稳定,即使单个cvf也可能导致算法完全失败,从而使它无法从这种方法中受益。
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引用次数: 7
Efficient dispersion of mobile robots on graphs 移动机器人在图上的高效分散
A. Kshemkalyani, Faizan Ali
The dispersion problem on graphs requires k robots placed arbitrarily at the n nodes of an anonymous graph, where k ≤ n, to coordinate with each other to reach a final configuration in which each robot is at a distinct node of the graph. The dispersion problem is important due to its relationship to graph exploration by mobile robots, scattering on a graph, and load balancing on a graph. In addition, an intrinsic application of dispersion has been shown to be the relocation of self-driven electric cars (robots) to recharge stations (nodes). We propose five algorithms to solve dispersion on graphs. The first three algorithms require O(k log Δ) bits at each robot and O(m) steps running time, where m is the number of edges and Δ is the degree of the graph. The algorithms differ in whether they address the synchronous or the asynchronous system model, and in what, where, and how data structures are maintained. The fourth algorithm, for the asynchronous model, has a space usage of O(D log Δ) bits at each robot and uses O(ΔD) steps, where D is the graph diameter. The fifth algorithm, for the asynchronous model, has a space usage of O(max(log k, log Δ)) bits at each robot and uses O((m - n)k) steps.
图上的分散问题需要k个机器人任意放置在匿名图的n个节点上,k≤n,相互协调,以达到每个机器人在图的不同节点上的最终构型。分散问题是一个重要的问题,因为它与移动机器人的图探索、图上的分散和图上的负载平衡有关。此外,分散的一个内在应用已被证明是自动驾驶电动汽车(机器人)重新安置到充电站(节点)。我们提出了五种算法来解决图上的色散。前三种算法在每个机器人上需要O(k log Δ)位和O(m)步运行时间,其中m是边的数量,Δ是图的度。这些算法的不同之处在于它们处理的是同步系统模型还是异步系统模型,以及维护数据结构的内容、位置和方式。对于异步模型,第四种算法在每个机器人上的空间使用为O(D log Δ)位,并使用O(ΔD)步,其中D是图直径。对于异步模型,第五种算法在每个机器人上的空间使用为O(max(log k, log Δ))位,并使用O((m - n)k)步。
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引用次数: 33
Distributed symmetry-breaking with improved vertex-averaged complexity 改进顶点平均复杂度的分布式对称破坏
Leonid Barenboim, Y. Tzur
We study the distributed message-passing model in which a communication network is represented by a graph G = (V, E). Usually, the measure of complexity that is considered in this model is the worst-case complexity, which is the largest number of rounds performed by a vertex ν ∈ V. While often this is a reasonable measure, in some occasions it does not express sufficiently well the actual performance of the algorithm. For example, an execution in which one processor performs r rounds, and all the rest perform significantly less rounds than r, has the same running time as an execution in which all processors perform the same number of rounds r. On the other hand, the latter execution is less efficient in several respects, such as energy efficiency, task execution efficiency, local-neighborhood efficiency and simulation efficiency. Consequently, a more appropriate measure is required in these cases. Recently, the vertex-averaged complexity was proposed by [13]. In this measure, the running time is the worst-case average of rounds over the number of vertices. Feuilloley [13] showed that leader-election admits an algorithm with significantly better vertex-averaged complexity than worst-case complexity. On the other hand, for O(1)-coloring of rings, the worst-case and vertex-averaged complexities are the same. This complexity is Θ (log* n) [13]. It remained open whether the vertex-averaged complexity of symmetry-breaking in general graphs can be better than the worst-case complexity. In this paper we devise symmetry-breaking algorithms with significantly improved vertex-averaged complexity for both general graphs, as well as specific graph families. Some algorithms of ours have significantly better vertex-averaged complexity than the best-possible worst case complexity. In particular, for general graphs, we devise an O(a)-forests-decomposition algorithm with a vertex-averaged complexity of O(1) rounds, where the arboricity a is the minimum number of forests that the graph's edges can be partitioned into. In the worst-case, this requires Ω(log n) rounds [10]. In addition, for graphs with constant arboricity a, we compute (Δ + 1)-vertex-coloring, Maximal Independent Set, Maximal Matching and (2Δ - 1)-edge-coloring, deterministically, with O (log* n) vertex-averaged complexity. The best known deterministic algorithms for (Δ + 1)-coloring have time complexity [MATH HERE] in the worst case [3,14], and the best known Maximal Independent Set and Maximal Matching algorithms on these graphs have worst-case complexity at least [MATH HERE] [10, 18]. In addition to deterministic algorithms, we devise randomized algorithms, in which the vertex-averaged bounds hold with high probability. In particular, we show that (Δ + 1)-coloring of general graphs requires O(1) vertex-averaged complexity, with high probability. This is in contrast to the worst case complexity, which is Ω (log* n) even on rings [19].
我们研究了分布式消息传递模型,其中通信网络由图G = (V, E)表示。通常,该模型中考虑的复杂度度量是最坏情况复杂度,即顶点ν∈V执行的最大轮数。虽然这通常是一个合理的度量,但在某些情况下,它不能很好地表达算法的实际性能。例如,一个处理器执行r轮,而所有其他处理器执行的轮数明显少于r的执行,与所有处理器执行相同轮数r的执行具有相同的运行时间。另一方面,后一种执行在几个方面效率较低,例如能源效率、任务执行效率、局部邻域效率和模拟效率。因此,在这些情况下需要采取更适当的措施。最近,[13]提出了顶点平均复杂度。在这种度量中,运行时间是顶点数上轮数的最坏情况平均值。Feuilloley[13]表明,leader-election允许一个顶点平均复杂度明显优于最坏情况复杂度的算法。另一方面,对于O(1)个环着色,最坏情况和顶点平均复杂性是相同的。这个复杂度是Θ (log* n)[13]。一般图中对称破缺的顶点平均复杂度是否优于最坏情况复杂度,仍然是一个开放的问题。在本文中,我们设计了具有显著提高顶点平均复杂度的对称破坏算法,用于一般图和特定图族。我们的一些算法有明显更好的顶点平均复杂度比最佳可能的最坏情况的复杂度。特别地,对于一般图,我们设计了一个O(a)-森林分解算法,其顶点平均复杂度为O(1)轮,其中树性a是图的边可以划分成的最小森林数。在最坏情况下,这需要Ω(log n)四舍五入[10]。此外,对于具有常数树性a的图,我们确定性地计算(Δ + 1)-顶点着色、最大独立集、最大匹配和(2Δ - 1)-边着色,具有O (log* n)顶点平均复杂度。最著名的(Δ + 1)着色的确定性算法在最坏情况下具有时间复杂度[MATH HERE][3,14],而这些图上最著名的最大独立集和最大匹配算法至少具有最坏情况复杂度[MATH HERE][10,18]。除了确定性算法外,我们还设计了随机化算法,其中顶点平均边界具有高概率。特别地,我们证明了一般图的(Δ + 1)着色需要O(1)个顶点平均复杂度,具有高概率。这与最坏情况下的复杂度形成对比,即使在环[19]上也是Ω (log* n)。
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引用次数: 9
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Proceedings of the 20th International Conference on Distributed Computing and Networking
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