DOS攻击技术及其防范

DoS,即拒绝服务攻击,是一种常见而有效的网络攻击技术,它通过利用协议或系统的缺陷,采取欺骗或伪装的策略来进行网络攻击,最终使受害者因为资源耗尽或无法作出正确响应而导致瘫痪,从而无法向合法用户提供正常服务。DoS的最新发展趋势是DDoS。本文介绍了DoS攻击的原理,所利用的相关协议及其漏洞特点,常见的DoS攻击手段或程序,以及如何防范DoS攻击。     

速查Apache最新漏洞

在六月份 Oracle 公司易损性检测过程中,工程师 Mark Litchfield 发现了对 Apache 在 Windows 平台上的拒绝服务攻击,后经Apache 软件基地测试发现,Apache 在处理以分块(chunked)方式传输数据的 HTTP 请求时存在设计漏洞,远程攻击者可能利用此漏洞在某些 Apache 服务器上以 Web 服务器进程的权限执行任意指令或进行拒绝服务攻击。对于1.3到1.3.24(含1.3.24)版本的 Apache,现在已经证实在 Win32系统下,远程攻击者可能利用这一漏洞执行任意代码。在 UNIX 系统下,利用这一漏洞执行代码可能是非常     

基于包标记的DoS(DDoS)攻击源追踪技术

网络协议的固有缺陷以及操作系统的漏洞，使得网络的安全性能很差．即使是一个几岁的小孩，通过网络上下载的一些工具．进行简单的操作就可以发起攻击。其中，拒绝服务攻击DoS(Denial of Service)和分布式拒绝服务攻击DDoS(Distributed Denial of Service)攻击，利用了TCP协议的三次握手机制，易于实现。一个典型的例子．在2000年和2002年，几大著名网站yahoo、eBay和Amazon等遭到了黑客的DDoS攻击，     

基于协议转变的拒绝服务攻击技术的研究

提出了协议转变的概念,分析这种转变潜在的缺陷;在此基础上,着重阐述如何通过这种协议转换进行拒绝服务攻击,分析这种拒绝服务攻击手段的特点。最后,针对这种攻击手段提出了一些防御措施,并预测这种攻击手段的发展前景。     

捷普WEB安全建设方案

0前言 近年来．网站安全问题越来越复杂．Web服务器以其强大的计算能力、处理性能及所蕴含的高价值逐渐成为主要攻击的目标．特别是涉及到支付交易等平台．更容易成为攻击的目标。针对网站的各类安全威胁正在飞速增长．如DDoS攻击（分布式拒绝服务攻击）、缓冲区溢出攻击,恶意远程文件执行、目录遍历攻击以及当前新兴的SQL注入和跨站脚本攻击。本质上,这些攻击手段都是充分利用了各类安全漏洞,如TCP／IP协议设计存在的安全隐患．系统漏洞以及Web应用程序漏洞以及配置错误。采用这些攻击手段,攻击者可以实现拒绝服务网页篡改或是网页挂马．网站将蒙受巨大的经济损失或政治影响。     

RFID分布式密钥阵列认证协议的安全性分析

RFID技术已广泛地应用在诸如访问控制、支付系统、票务系统以及供应链管理等领域,但同时安全和隐私问题变得越来越严重。安全认证协议的设计与完善对于保护信息安全和用户隐私变得更加重要。2011年H.Ning等人提出分布式可扩展密钥阵列认证协议（KAAP）,该协议采用分布式密钥阵列架构、访问列表机制和动态随机数机制来抵御系统外部攻击和内部假冒攻击。针对KAAP建立两种有效的攻击模型,在此基础上分析得出该认证协议不能有效地抵御来自外部的重放攻击和拒绝服务攻击。KAAP安全性存在漏洞,不能达到设计的预期目标。     

拒绝服务攻击的分析和防范

由于现有网络体系结构和网络协议中的缺陷和弱点,以及多年来网络系统累积下了无数的漏洞,使得网络安全越来越成为人们关注的焦点。拒绝服务攻击是黑客攻击系统时经常用到的一种方法,黑客们正醉心于对它的研究,而无数的网络用户将成为这种攻击的受害者。拒绝服务攻击的手段很多,给研究者的分析、判定、防御和恢复造成了很大困难。该文从多个方面对拒绝服务攻击进行了剖析,预测了发展趋势,提出了系统的防御解决方案。同时还给不负责任或缺乏经验的网络管理员敲响了警钟,必须加强安全意识,不断提高和强化网络安全设施,维护网络安全是大家共同的职责。     

企业网站常见攻击及其应对策略

企业网站会经常受到黑客的攻击，主要讨论常见的脚本漏洞、旁注、缓冲区溢出、分布式拒绝服务、解码攻击等五种攻击方式及其应对策略。     

基于802.15.4的低速率拒绝休眠攻击及其防御机制研究

拒绝休眠攻击是一类致力于快速耗尽节点能量的特殊拒绝服务攻击,无线传感器网络如何防御恶意节点的低速率拒绝服务攻击,保障节点正常生命周期是一个重要的问题.IEEE 802.15.4作为目前无线传感器网络较常使用的一种MAC协议,存在着信标广播漏洞.本文首次提出了一种针对该漏洞的拒绝休眠攻击方法及其防御机制,并通过仿真实验验证了攻击的危害性和防御机制的有效性.     

基于IEEE 802.11认证协议的DoS攻击

对IEEE802. 11认证协议的漏洞和无线网络受到的拒绝服务 (DoS)攻击进行了深入的剖析。捕获并分析IEEE802. 11MAC帧,利用序列号分析的方法,对授权的合法客户受到的DoS攻击进行检测;利用统计分析方法,对访问接入点AP受到的DoS攻击进行检测。     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.