SDN环境下基于改进D-S理论的DDoS攻击检测

软件定义网络(software-defined networking, SDN)实现了控制层和转发层设备的分离, 但控制转发的解耦使得SDN网络中不同层次设备面临新型的DDoS攻击风险. 为了解决上述问题, 本文提出了一种SDN环境下基于改进D-S理论的DDoS攻击检测方法, 用于检测以SDN控制器和交换机为目标的DDoS攻击. 在改进的算法中, 本文使用离散因子和纯度因子衡量D-S证据源之间的冲突. 同时, 结合纯度因子和离散因子调整D-S证据理论的证据源, 调整后的证据源将通过Dempster规则融合得到DDoS攻击检测结果. 实验结果表明本文提出的方法具有较高的精度.     

基于SDN的DDoS攻击防御系统

软件定义网络（SDN）是一种新兴网络架构,通过将转发层和控制层分离,实现网络的集中管控。控制器作为SDN网络的核心,容易成为被攻击的目标,分布式拒绝服务（DDoS）攻击是SDN网络面临的最具威胁的攻击之一。针对这一问题,本文提出一种基于机器学习的DDoS攻击检测模型。首先基于信息熵监控交换机端口流量来判断是否存在异常流量,检测到异常后提取流量特征,使用SVM+K-Means的复合算法检测DDoS攻击,最后控制器下发丢弃流表处理攻击流量。实验结果表明,本文算法在误报率、检测率和准确率指标上均优于SVM算法和K-Means算法。     

SDN中交换机控制代理拒绝服务攻击研究

针对软件定义网络(SDN)交换机控制代理吞吐量有限的不足,提出一种交换机控制代理拒绝服务攻击方法。为保护SDN交换机控制代理资源,设计层次化多阈值的攻击检测方案,通过计算SDN交换机及交换机各端口所关联的Packet-In消息的速率,并将其与给定的阈值进行比较来检测攻击。实验结果表明,该方法可实时检测交换机控制代理拒绝服务攻击,与同类攻击检测方法相比,不仅能够识别攻击流量,定位攻击发生的位置,而且不需要改变网络架构。     

SDN环境下的LDoS攻击检测与防御技术

低速率拒绝服务(LDoS)攻击是一种新型的网络攻击方式,其特点是攻击成本低,隐蔽性强。作为一种新型的网络架构,软件定义网络(SDN)同样面临着LDoS攻击的威胁。但SDN网络的控制与转发分离、网络行为可编程等特点又为LDoS攻击的检测和防御提供了新的思路。提出了一种基于OpenFlow协议的LDoS攻击检测和防御方法。通过对每条OpenFlow数据流的速率单独进行统计,并利用信号检测中的双滑动窗口法实现对攻击流量的检测,一旦检测到攻击流量,控制器便可以通过下发流表的方式实现对攻击行为的实时防御。实验表明,该方法能够有效检测出LDoS攻击,并能够在较短时间内实现对攻击行为的防御。     

软件定义网络中的异常流量检测研究进展

软件定义网络(software defined networking,简称SDN)是一种新型的网络架构.SDN将控制层从数据层分离并开放网络接口,以实现网络集中控制并提高网络的可扩展性和编程性.但是SDN也面临诸多的网络安全威胁.异常流量检测技术可以保护网络安全,防御恶意流量攻击.对SDN异常流量检测进行了全面的研究,归纳了数据平面和控制平面可能遭受到的网络攻击;介绍并分析了位于应用平面、控制平面和中间平台的异常流量检测框架;探讨了异常流量识别机制、负载均衡机制、异常流量追溯机制和异常缓解机制;最后指明SDN异常流量检测在未来工作中的研究方向.     

基于SDS架构的多级DDoS防护机制

随着互联网的高速发展,网络安全的问题越来越严峻。软件定义网络（SDN）的出现为解决网络安全问题提供了全新的解决方案,如软件定义安全（SDS）。在SDS架构的基础上,针对分布式拒绝服务（DDoS）攻击的特点,提出一种新的DDoS防护机制SDS for DDoS。这种防护机制结合了以往检测方式和防护方式的优点,将安全服务原子化,并实现安全策略盒的多级防护策略。在受到DDoS攻击时,机制可以根据检测到的攻击力度进行动态决策,还能先验式地对攻击流量进行阻隔,不仅增加了决策的可信度,还解决了以往所采用的静态防护和后验式防护的不足。实验验证了机制的可行性,能有效地避免服务器受到DDoS攻击,更突出了它在决策时的灵活性和在遭受攻击时的先验性。     

SDN中基于C4.5决策树的DDoS攻击检测

SDN（Software Defined Network,软件定义网络）是一种新兴的网络架构,它的控制与转发分离架构为网络管理带来了极大的便利性和灵活性,但同时也带来新的安全威胁和挑战。攻击者通过对SDN的集中式控制器进行DDoS（Distributed Denial of Service,分布式拒绝服务）攻击,会使信息不可达,造成网络瘫痪。为了检测DDoS攻击,提出了一种基于C4.5决策树的检测方法：通过提取交换机流表项信息,使用C4.5决策树算法训练数据集生成决策树对流量进行分类,实现DDoS攻击的检测,最后通过实验证明了该方法有更高的检测成功率,更低的误警率与较少的检测时间。     

企业应用SDN的安全利弊

软件定义网络（SDN）将网络从硬件平面转移到了软件平面,受到软件控制器的管理。其好处包括自动化和简化网络管理工作以及提高应用程序性能。但同时,作为一项新的技术,SDN也很容易受到攻击。首先,根据Casaba Security公司共同创始人ChrisWeber表示,将控制集中到SDN控制器中能够模糊了防护的分层硬件的界限,例如防火墙。     

面向针对性攻击的SDVN控制层鲁棒性方案

将软件定义网络应用于车联网能显著提升其性能,但该方法也面临传统SDN要应对的安全问题.基于软件定义车联网体系架构中控制平面可能面临的针对性节点攻击问题,提出一种鲁棒的控制器放置方法.该方法结合传统的SDN控制平面部署问题,首先将控制平面鲁棒性问题建模为交换机与控制器的连通冗余性问题,提升交换机在极端情形下与控制器的连通...     

面向软件定义网络的两级DDoS攻击检测与防御

分布式拒绝服务(DDoS)攻击一直是互联网的主要威胁之一,在软件定义网络(SDN)中会导致控制器资源耗尽,影响整个网络正常运行。针对SDN网络中的DDoS攻击问题,文章设计并实现了一种两级攻击检测与防御方法。基于控制器北向接口采集交换机流表数据并提取直接特征和派生特征,采用序贯概率比检验(Sequential Probability Ratio Test,SPRT)和轻量级梯度提升机(LightGBM)设计两级攻击检测算法,快速定位攻击端口和对攻击类型进行精准划分,通过下发流表规则对攻击流量进行实时过滤。实验结果表明,攻击检测模块能够快速定位攻击端口并对攻击类型进行精准划分,分类准确率达到98%,攻击防御模块能够在攻击发生后2 s内迅速下发防御规则,对攻击流量进行过滤,有效保护SDN网络的安全。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。