网络蠕虫扩散策略研究

蠕虫在传播时所采取的扫描策略直接决定了蠕虫的感染速度和程度.论文对蠕虫传播时采用的不同扫描策略进行了深度分析,并建模比较.针对各种扩散策略的不足,提出了随机均匀扫描、基于路由扫描和预定义目标地址列表相结合的扫描策略,简称RRH-1扫描策略.经验证,和已有单一扩散策略相比,采用RRH-1扫描策略的蠕虫传播时具有快速、准确和流量小的优点.     

基于双层扫描策略的IPv6蠕虫研究*

由于IPv6网络地址空间巨大,传统的基于随机扫描、顺序扫描等网络层扫描策略的IPv4蠕虫难以在IPv6网络中传播。构建了一种新型IPv6网络蠕虫——V6-Worm,该蠕虫运用双层扫描策略,在子网内和子网间分别采用基于组播和基于域间路由协议路由前缀的扫描策略,并在此基础上建立了一种双层蠕虫传播模型(double layer model,DLM)来仿真V6-Worm的传播趋势。仿真结果表明,V6-Worm可在大规模IPv6网络中传播,与采用随机扫描策略的CodeRed相比,V6-Worm具有更快的传播速度。     

基于非均匀扫描的蠕虫传播策略研究

蠕虫在因特网上的传播速度对网络安全有着严重的影响。对蠕虫传播方式的深入研究有利于找到更有效的手段防卫蠕虫的快速传播。本文主要围绕蠕虫的传播方式进行研究,提出了一种基于因特网应用非均匀分布的蠕虫扫描策略。对于该蠕虫扫描策略;在模拟平台NS2上实现了蠕虫模型的模拟。结果表明,非均匀扫描的蠕虫传播速度比起随机均匀扫描的蠕虫显著加快。     

IPv6网络中DNS蠕虫的研究

基于IPv6网络环境分析了网络蠕虫的扫描策略,构建了一种新型网络蠕虫--DNSWorm-V6,该蠕虫应用两层不同的扫描策略,即在本地应用子网内扫描策略,在子网间应用DNS扫描策略.由此两层扫描策略,提出一种双层蠕虫传播模型TLM.仿真实验结果表明,DNSWorm-V6是一种可以在IPv6网络中大范围快速传播的蠕虫.可以预测IPv6网络中新型蠕虫可能带来的威胁.     

网络蠕虫的扫描策略分析

网络蠕虫已经严重威胁了网络的安全.为了有效防治网络蠕虫,首要任务必须清楚有什么扫描方法,以及这些扫描方法对蠕虫传播的影响.为此,本文构建了一个基于离散时间的简单蠕虫传播模型,通过对Code Red蠕虫传播的真实数据比较,验证了此模型的有效性.以此模型为基础,详细分析了蠕虫的不同扫描策略,如均匀扫描、目标列表扫描、路由扫描、分治扫描、本地子网、顺序扫描、置换扫描,并给出了相应的模型.     

IPv6网络中蠕虫传播模型及分析

IPv6网络由于其巨大的地址空间，通常被认为对随机扫描蠕虫有天然的抵御能力，该文研究了一种可以在IPv6网络中迅速传播的新型网络蠕虫（V6-Worm）．基于对V6-Worm扫描策略的分析，分别建立简单传染病模型和双因素蠕虫模型来仿真V6-Worm的传播趋势．简单传染病模型的仿真结果证明，V6-Worm拥有比随机扫描蠕虫更快的传播速度；双因素蠕虫模型的仿真结果证明，V6-Worm拥有更强的对抗蠕虫控制措施的能力，同时在研究中发现主机中存在漏洞的比例是V6-Worm传播性能的主要影响因素．最后，文中从防止地址信息泄漏和降低主机存在漏洞比例两个角度，讨论了V6-Worm的防御策略．     

良性蠕虫SRF扩散模型研究

良性蠕虫是一种智能化、自动化的,综合了网络攻击、密码学和计算机病毒技术,无需计算机使用者干预即可运行的攻击程序或代码。良性蠕虫的应用前景广阔,但它传播时对网络造成的冲击使得这一技术的应用减缓,而良性蠕虫流量产生的主要环节是扫描探测阶段和繁殖阶段。本文针对这一特点提出了SRF扩散模型,该模型在扫描探测阶段可采用有序化、分级化和RRH-l传播策略,在繁殖阶段结合有限繁殖算法和频度自适应的动态副本控制机制。经验证,和已有策略相比,SRF扩散模型在扫描探测阶段可减少扫描探测流量近40%,在繁殖阶段可精确控制蠕虫副本的数量,从而使其流量达到一个可控制的水平。     

基于平衡树的良性蠕虫扩散策略

网络蠕虫已对网络系统安全造成重要威胁，传统防范措施已不再适用．使用良性蠕虫来对抗蠕虫正成为一种新的应急响应技术．提出了良性蠕虫基于网络拓扑信息的扩散技术，并重点研究了基于平衡树的良性蠕虫扩散算法、平衡树的动态生成规则和稳定性增强策略．最后给出一个蠕虫对抗模拟实验，结果表明，和已有的传播策略相比，采用扩散平衡树策略的良性蠕虫扩散速度更快，产生流量影响更小．     

IPV6网络中搜索引擎蠕虫的传播研究

针对传统蠕虫传播模型无法准确预测基于搜索引擎的蠕虫的传播问题,在IPv6网络环境下构建了一种基于搜索引擎的蠕虫-V6.MAMWorm,并在分层扫描策略的基础上提出了一种混合智能算法.在本地应用子网内扫描策略,在子网间应用搜索引擎扫描策略,从而建立了一种新型的蠕虫传播模型(multi-tierarchitecturemodel,MAM).仿真结果表明,V6-MAM-Worm在IPv6网络中具有更快的传播速度,其将对IPv6网络的安全性带来巨大的威胁.     

分层叠加网的良性蠕虫低耗扩散策略

为降低良性蠕虫网络带宽消耗和提高传播速度,提出基于分层叠加网的良性蠕虫扩散模型—HOPM（Hierarchy Over-lay Propagation Model）和基于周期性反馈策略的自适应良性蠕虫传播控制算法—FBSP（Feed Back Self-adapting Propagation Algorithm）.分层叠加网模型具有逼近物理网结构、自适应网络变化的特点;FBSP算法跟踪蠕虫与良性蠕虫的交互过程,根据周期性反馈信息实时调整良性蠕虫的传播范围和策略来控制其网络带宽消耗.仿真实验表明在宏观网络环境下,基于分层叠加网的良性蠕虫扩散的通信负荷为基于Landmark叠加网模型的30%-50%.     

Strategies and tactics in fault diagnosis

Large individual differences in the ability to diagnose novel system failures are often noted in the research literature. Recent evidence suggests that measures of reflective cognitive styles may be good predictors of fault diagnosis performance.

In Experiment 1 the styles or strategies developed by novice problem solvers for context independent fault diagnosis tasks were examined in detail. Two different strategies, similar to focusing and scanning strategies described by previous researchers, were found to be consistently adopted by subjects. Experiment 2 showed that a measure of focusing and scanning strategies predicted diagnosis performance better than a measure of reflectivity. In addition it was found that the amount of between subjects' variation that could be accounted for increased as subjects became more practiced at fault-finding.     

Strategies in Programming Languages Today

This paper provides a brief account of motivation, themes, and research directions leading to the round table on Strategies in Programming Languages Today organized as part of the 4th International Workshop on Reduction Strategies in Rewriting and Programming (WRS'04).     

概率模型检测在动态能耗管理中的应用

如何平衡嵌入式设备的能耗和性能表现,成为了一个热门话题。动态能耗管理是一种在保证系统性能的基础上降低其能耗的有效方法,其关键点是如何生成有效的动态能耗管理策略。在概率模型检测技术的基础上,提出了一种生成和验证动态能耗管理策略的方法。首先对目标系统和能耗管理目标建模,然后利用PRISM-games工具进行动态能耗管理策略的合成,同时利用模型检测工具PRISM对合成的动态能耗管理策略进行验证。实验表明,该方法具备可行性和有效性。     

一种具有隐蔽性的网络扫描器的设计与实现

本文由整体到局部对网络扫描中的隐蔽性要求和各类技术的隐蔽性现状作了较为详细地分析和论述。依据实际要求,综合考量隐蔽性、可靠性和扫描效率等多个方面,设计并实现了一种具有隐蔽性的网络扫描器。     

端口扫描与反扫描技术

本文首先分析网络端口扫描的技术基础,然后从实现的角度分析了各种端口扫描的实现方法,最后给出了一个反端口扫描的实用解决方案。     

应用职业生涯规划理论促进高校辅导员队伍建设

本文运用职业生涯规划相关理论,分析职业生涯规划对高校辅导员的重要性,研究高校辅导员生涯规划策略,为高校加强辅导员队伍建设提供方法和途径。     

计算机网络应用中的安全性评价及对策研究

在现代社会中,信息技术的发展给人们带来了以前所不可想象的方便与便捷.计算机网络技术作为信息技术的重要方面之一,也得到了前所未有的进步,从而使得信息资源得到充分的分享和高效的利用.然而,人们在享受计算机网络应用的便利的同时,在计算机网络应用过程中所出现的安全性问题也不可忽视.本文在介绍了部分计算机网络应用现状的基础上,分析了计算机网络应用中所出现的一些安全性问题,并在此基础之上探讨和研究了几点解决计算机网络应用安全问题的对策.     

Performance and human factors: considerations about cognition and attention for self-paced and externally-paced events

The cognitive psychology school of thought has spawned models of sequential stages or phases of information processing associated with various tasks. It has encouraged the study of cognitions and attention as related to learning, performance and high levels of achievement in goal-directed complex activities in which movement is the medium of expression. Although more recently proposed dynamical systems models challenge the simplicity of this approach, there is little doubt that the ability to learn as well as to excel in performing movement skills depends to a great degree on the effective self-regulation of cognitive processes in a variety of situations. What to think about (or not think about) prior to, during and even after an event can have great consequences on present and subsequent performance. Relevant externally-provided and selfgenerated strategies should enable these processes to function at an optimal level, and are the subject of an increasing amount of research. For such purposes, it is convenient to categorize events as self-paced (closed) and externally-paced (open). Examples of both types of events exist in sport as well as in various occupations and recreational activities, with different information processing demands associated with each one. Any breakdown in a particular stage of processing will potentially lead to poorer performance. Special training techniques and strategies are evolving from the cognitive and psychophysiological research literature that might improve the level of functioning at each stage for either self-paced or externally-paced skills.     

Improving children’s reading comprehension and use of strategies through computer-based strategy training

In this study, the attention–selection–organization–integration–monitoring (ASOIM) model, revised from Mayer’s [Mayer, R. E. (1996). Learning strategies for making sense out of expository text: The SOI model for guiding three cognitive processes in knowledge construction. Educational Psychology Review, 8, 357–371] SOI model of text comprehension, was used as a foundation to design a multi-strategy based system, which was named Computer Assisted Strategy Teaching and Learning Environment (CASTLE). CASTLE aims to enhance learners’ abilities of using reading strategies and text comprehension. The effects of CASTLE on students with different reading abilities were empirically evaluated. 130 sixth graders took part in an 11-week computer-based reading strategies course. The results show that CASTLE helps to enhance the students’ use of strategies and text comprehension at all ability levels.