DDoS攻击方式与防御措施浅议

随着Internet互联网络带宽的增加和多种DDoS黑客工具的不断发布,DDoS拒绝服务攻击的实施越来越容易,DDoS攻击事件正在成上升趋势。论文通过对常用的各种DDoS攻击方式进行分类,对攻击的原理进行了探讨,最后在此基础上有针对性地提出了一些防御DDoS攻击的方法。     

DDoS攻击原理及其防御机制的研究

DDoS攻击是一种被黑客广泛应用的攻击方式,它以破坏计算机系统或网络的可用性为目标,危害性极大。本文首先介绍了DDoS攻击的攻击原理,接着从DDoS攻击的攻击手段和攻击方式两个方面对DoS攻击进行分类介绍,然后针对DDoS攻击的方式,提出了一种检测和防御DDoS攻击的模型,最后利用入侵检测技术和数据包过滤技术,设计了一个针对DDoS攻击的检测与防御系统,该系统具有配置简单、易于扩展、实用性较强等优点。     

DDoS防御技术综述

分布式拒绝服务攻击(DDoS)是Internet面临的最严峻的威胁之一。本文介绍了DDoS攻击原理,总结了近年来防御技术的研究成果,对DDoS防御技术进行了分析,指出了防御DDoS攻击面临的挑战。     

DDoS攻击的技术分析与防御策略

系统地分析分析了DDoS攻击的实现原理,列举了发动DDoS攻击的常用工具,针对攻击产生的机理,提出了详细可行的DDoS攻击防御策略.最后给出市场上典型DDoS攻击检测与响应系统的主要性能和防御DDoS攻击的研究方向.     

北京联通防DDoS攻击服务介绍

近年来的互联网DDoS攻击日渐增多,其攻击方式多样难于防御.越来越多的客户尤其是银行客户,提出了防DDoS攻击服务的需求以保障其网银业务的安全性.本文说明了DDoS攻击的基本原理,概括了客户在攻击前、攻击中和攻击后三个阶段对防DDoS服务的需求.介绍了北京联通防DDoS攻击服务的系统建设、服务内容和实际应用,最后进行了...     

分布式拒绝服务攻击及防御机制研究

分布式拒绝服务(DDoS)攻击是当今网络面临的最严峻的威胁之一,研究防御DDoS攻击的技术非常重要。文章分析了DDoS攻击原理,并深入介绍了当前DDoS攻击的防御技术。     

基于隐马尔可夫模型的医院通信网络DDoS攻击检测方法

常规的医院通信网络DDoS攻击检测矩阵结构一般设定为独立形式,致使攻击检测范围的扩大受到限制,进而一定程度上导致DDoS攻击检测召回率下降。针对上述问题,文章提出了一种基于隐马尔可夫模型的医院通信网络DDoS攻击检测方法。该方法根据当前的测定需求及标准对DDoS攻击进行特征提取,采用多目标的方式设计检测矩阵,解析DDoS攻击方向具体位置以及攻击的范围。在此基础上,构建隐马尔可夫医院通信网络DDoS攻击检测模型,采用多元识别+组合处理的方式来实现DDoS攻击的检测目标。测试结果表明：采用本文所设计的方法,DDoS攻击检测召回率可以达到80%以上,对于医院通信网络的攻击检测效率更高,泛化能力明显提升,具有实际的应用价值。     

一种新的DDoS攻击检测算法

为了准确及时的进行DDoS攻击检测,提出了一种新的DDoS攻击检测算法。该算法在基于传统的小波分析检测DDoS攻击的基础上融入了主成分分析法和小波分析法中DDoS检测方法,并根据该算法设计相应的模型和算法来检测 DDoS 攻击,并且引入信息论中的信息熵对源IP地址的分散程度进行度量,根据初始阶段Hurst指数及熵值的变化自适应地设定阈值以检测攻击的发生。实验结果表明,该方法大幅度的提高了DDoS检测的速度。     

ISP防御DDoS攻击机制研究

通过对DDoS攻击的原理及特征进行分析,并根据ISP在网络中的地位和作用,讨论了DDoS攻击的监测和防御方法,提出了建立分布式防御系统来应对DDoS攻击的方法。     

基于小波分析的网络低速率DDoS攻击检测方法

为减少网络DDoS（分布式拒绝服务）攻击检测误报率,实现对网络DDoS攻击的精准检测,有针对性地调节网络的运行速率,文章设计一种基于小波分析的网络低速率DDoS攻击检测方法。提取DDoS攻击特征,布设异常攻击定位节点,识别异常波段进行同步处理,构建小波分析DDoS攻击检测模型。最终的测试结果表明,对比于传统攻击检测小组,文章设计的小波分析DDoS攻击检测小组误差较小,检测效率较高,具有一定的应用价值。     

Algorithms for Dynamic Routing in All-Optical Networks

In this paper, we have studied a number of algorithms for routing in all-optical wavelength routed networks. We have considered situations where a lightpath is dynamically created in response to a request for communication and the WDM channels constituting the lightpath are reclaimed when the communication is over. We have looked at two schemes for dynamic wavelength allocation. In the first scheme we have assumed the existence of a central agent to maintain a database of existing lightpaths where the central agent attempts to generate a new lightpath in response to a request for communication. In the second scheme, we attempt to generate a new lightpath using a distributed algorithm. In the first scheme we have exploited the existence of multiple paths between any pair of nodes in a network in order to reduce the blocking probability. For the second scheme, we have proposed three distributed strategies to determine, if possible, a lightpath when there is a request for communication. Each of these strategies have their advantages and disadvantages in terms of the expected blocking probability and the set-up time. We have studied the performances of both the schemes using Monte Carlo simulation.     

语音编辑播放系统的应用研究

首先对语音系统的目前应用状况和未来的发展趋势进行详细的分析,接着对文语转换系统的结构组成和工作原理做了明确的说明和分析。最后从软件工程的角度,通过一个具体的设计案例:在VB中使用TTS技术实现语音的编辑和播放,详细地说明在高级语言中运用TTS技术实现语音的编辑和播放的过程,并说明了系统的不足和具体的改进方案。     

Change, courage, and responsibility [managing change post 9/11]

Acknowledging the sea change that has occurred in the USA following 9/11, we have to be cognizant of the fact that, as a result, our lives will most certainly change. How will our companies deal with the unexpected impact of this tragedy? And how are individuals in the companies managing the change that is inevitable in light of the present economic and political circumstances? What do individuals have to do in order to promote greater productivity within a company? We can no longer be complacent in our jobs or in our lives as a whole if we are going to continue to be the great nation that we are. We have to take responsibility and be proactive in our jobs. And this takes courage. We have to come to grips with habits and thinking that keep us bound to the past. We have to see that our fellow workers are properly trained; we have to take responsibility for that training, whether we give it or receive it. We have to be open to suggestions and take responsibility for making suggestions as well as implementing them.     

Two privacy-preserving protocols for point-curve relation

Numerous privacy-preserving issues have emerged along with the fast development of Internet, both in theory and in real-life applications. To settle the privacy-preserving problems, secure multi-party computation is essential and critical. In this paper, we have solved two problems regarding to how to determine the position relation between points and curves without revealing any private information. Two protocols have been proposed in order to solve the problems in different conditions. In addition, some building blocks have been developed, such as scalar product protocol, so that we can take advantage of them to settle the privacy-preserving computational geometry problems which are a kind of special secure multi-party computation problems. Moreover, oblivious transfer and power series expansion serve as significant parts in our protocols. Analyses and proofs have also been given to argue our conclusion.     

Comparison of RF and microwave oxidation systems for the growth of thin oxides at low temperatures

Oxides have been grown on silicon using an oxygen plasma at substrate temperatures less than 600°C in two different oxidation systems. Slices from 18 mm up to 100 mm in diameter have been oxidised and have proved to have similar growth kinetics. Oxide fixed charge levels are in the range 1010?1011/cm2 with electrical breakdown strengths up to 12 MV/cm.     

基于扩频技术的跳频扩频分析

文章简述了扩频数字通信系统相关内容。在扩频技术基础上,引入了跳频扩频系统的模型,并对系统进行了较详细地分析。特别是对扩频跳频系统的特性和实现原理进行较全面地分析,得到了扩频跳频信号的关系数学表达式。同时,通过对跳频扩频的同步过程进行了分析,验证了跳频扩频通信有极强的抗干扰能力和多址通信能力。     

乳浊液非线性光学性质研究

本文利用单光束扫描法，对乳浊液中产生非线性光学现象的两种起源进行了研究，从而确定了它们各自对折射率变化的贡献，并对油／水和水／油两种乳浊液非线性光学性质进行了比较。     

Georegistration of airborne hyperspectral image data

A suite of geometric sensor and platform modeling tools has been developed which have achieved consistent subpixel accuracy in orthorectification experiments. Aircraft platforms in turbulent atmospheric conditions present unique challenges and have required creative modeling approaches. The geometric relationship between an image point and a ground object has been modeled by rigorous photogrammetric methods. First and second order Gauss-Markov processes have been used to estimate the platform trajectory. These methods have been successfully applied to HYDICE and HyMap data sets. The most important contributors to the subpixel rectification accuracy have been the first order Gauss-Markov model with control linear features     

光学触摸技术综述

光学触摸技术最初是1970年代引入的,最新的突破带来了该技术的复苏。研发者已经能够解决成本、亮环境光下的显示性能,以及组成要素等问题,这里只提及其中的一小部分。本文详细介绍了这些问题是如何解决的;该技术的前景,包括深入了解一下光学触摸系统的几个崭新的发展。     

Metal–Organic Framework Nanosheets: Programmable 2D Materials for Catalysis,Sensing, Electronics,and Separation Applications

Metal–organic framework nanosheets (MONs) have recently emerged as a distinct class of 2D materials with programmable structures that make them useful in diverse applications. In this review, the breadth of applications that have so far been investigated are surveyed, thanks to the distinct combination of properties afforded by MONs. How: 1) The high surface areas and readily accessible active sites of MONs mean they have been exploited for a variety of heterogeneous, photo-, and electro-catalytic applications; 2) their diverse surface chemistry and wide range of optical and electronic responses have been harnessed for the sensing of small molecules, biological molecules, and ions; 3) MONs tunable optoelectronic properties and nanoscopic dimensions have enabled them to be harnessed in light harvesting and emission, energy storage, and other electronic devices; 4) the anisotropic structure and porous nature of MONs mean they have shown great promise in a variety of gas separation and water purification applications; are discussed. The aim is to draw links between the uses of MONs in these different applications in order to highlight the common opportunities and challenges presented by this promising class of nanomaterials.