数据包标记技术综述

拒绝服务攻击（DoS）和分布式拒绝服务攻击（DDoS）一直是网络上使用频率最高的攻击方式。数据包标记技术作为一种重要应对攻击措施,是当前研究的一大热点。本文系统介绍了当前各种IP追踪中的数据包标记技术的研究成果,并对该技术的发展趋势做了简单的分析。     

常见网络攻击方法及其对策研究

综合叙述了常见的网络攻击方法,对探针、拒绝服务、R2L、U2R、数据5大类攻击方法进行了分析，并对SYN Floogding、DDoS、IP spofing 、Trojan、缓冲区溢出（Buffer-overflows）、TCP劫持等重要的攻击方法进行了具体的分析研究，最后，提出了“基于审计记录的入侵检测模型”作为网络安全攻击的对策。     

伪装IP追踪技术综述

1 引言网络协议和操作系统的缺陷导致了网络的安全问题。有关IP协议最重要的问题是IP地址的伪装。IP协议本身无法验证源地址段中的IP地址是发送者的IP地址。一台机器可以在一段时间内将自己伪装成另一台机器甚至路由器。对网络攻击各种各样的解决办法中IP追踪(traceback)是一种重在威慑的方法,一旦攻击者知道攻击能被追溯,进行攻击时会更慎重。在美国、日本等发达国家伪装IP追踪技术已成为学术界、企业界和政府部门普遍关心的重要问题之一。     

计算机网络系统攻击及防护方法

综合叙述了常见的网络攻击方法,对探测、拒绝服务、IP spoofing、缓冲区溢出(Buffer-overflow)、特洛伊木马攻击及TCP劫持等重要的攻击方法进行了具体的分析研究;最后提出了几种有效的计算机防护技术作为网络安全攻击的对策。     

DDoS攻击的检测与溯源探析

分布式拒绝服务攻击是当前流行的网络攻击手段之一,影响力巨大。本文主要探讨了DDoS攻击的检测方法和IP溯源技术,重点分析3种DDoS检测方法:流量、日志、数据包分析法,提出了运用数据包切片标记实现对伪造IP攻击溯源的方法。通过搭建分布式DDoS攻击实验环境,综合应用流量监控、日志分析和数据包切片标记的方法实现了对DDoS的IP溯源。通过反复实验测试,证明方法的可行性、准确率可达90%。     

一种基于IP签密在拒绝服务攻击中的设计与应用

针对拒绝服务攻击及分布式拒绝服务攻击的问题,设计和实现基于IP签密方案来抵抗此种入侵检测。提出一种利用椭圆曲线密码系统（ECC）的基于身份签名技术在可疑IP包经过的边界路由时进行签名验证的方案。与其他方案相比,基于ECC的IP回溯方案有较好的特性。     

防范DDOS的IP TraceBack技术

分布式拒绝服务攻击是当前网络发展面临的重大隐患之一。而防御分布式拒绝服务攻击的难点在于攻击者通常会使用虚假源IP地址的手段来欺骗受害者。IP TraceBack技术有效的解决了这个问题,即使攻击者任意地篡改源IP地址,IP TraceBack技术仍然可以找到攻击者所在的位置。本文对当前比较成熟的几种IP TraceBack技术做了详细介绍,并在此基础之上对这几种技术的优缺点做了比较和分析,最后进一步指出了IP TraceBack技术未来研究的方向。     

正态分布与分布式拒绝服务攻击的主动预防

随着信息技术的发展和应用的普及，网络安全问题已经成为人们关注的焦点问题。目前分布式拒绝服务（DDos，Distributed Denial of Service）攻击已经成为影响Internet正常运行的一个比较严重的问题，并影响合法用户获得正常的服务。文中首先阐述了DDoS形成的原理，然后分析了预防瞄攻击的措施和机制。随后借助于SSFNet（Scalable Simulation Framework Net）仿真软件构建相应的网络环境，模拟了一种分布式拒绝服务攻击。针对在实验中发现的攻击特征，即攻击发生时通过路由器的新IP数量呈现正态分布的变化趋势，结合统计学中正态分布的概率理论知识，提出了一种通过正态分布模型结合网络中新IP数量变化趋势应对分布式拒绝服务攻击的主动防御方案。然后利用实验中采集的数据，对所提出的应对分布式拒绝服务攻击的防御方案进行了验证。     

DDoS攻击下的IP追踪技术

DDoS（分布式拒绝服务）攻击正在对整个互联网产生巨大的危害和严重的经济损失，且不断增大。IP追踪技术用于反向追踪数据包到攻击源．在查找到攻击源之后可以对攻击源采取隔离或者其他方法从根本上阻止DDoS攻击。针对DDoS攻击，从实用性和可行性的观点出发，深入分析和探究了这些技术的优缺点，并重点突出了每个技术的改进方法。     

基于边采样包标记的IP源回溯系统

分析了一个基于边采样包标记的IP源回溯系统方案,给出了该方案的软件实现流程图和模拟程序,以确定网络攻击的真正来源,防范分布式拒绝服务攻击。     

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.