计算机专业英语论文(关于网络安全-入侵检测)_英文版

Abstract—With the development of computer network

technology,the risk of network intrusion also has greatly increased.But the traditional Encryption and firewall technology can’t meet the security need today. So the intrusion detection technology is being developed quickly in recent years,which is a new dynamic security mechanism in a set of detecting, preventing the behavior of system intrusion.Unlike the traditional security mechanism,intrusion detection has many features such as intelligent surveillance,real-time detection,dynamic response and so on.And in a sense,intrusion detection technology is a reasonable supplement of firewall technology.

Index Terms—network security,intrusion detection

I.THE N ECESSITY OF I NTRUSION D ETECTION

With the development of computer network technology,the destructive effects and losses of network attacks also have greatly increased.

The network security is becoming more and more complicated,the traditional and passive Encryption and firewall technology can’t against the diverse and complex attacks. Recently,intrusion is very easy to many computer competent,and there are many intrusion courses and tools.

So it’s of great significance and necessity to develop the Intrusion Detection System.

II.T HE DEVELOPMENT OF I NTRUSION D ETECTION S YSTEM In 1980,James P.Anderson wrote a book named “Computer Security Threat Monitoring and Surveillance”,which explained the concept of Intrusion Detection in detail ,the threat classifications of computer system and the idea of monitoring intrusion activities using auditing tracking data.

From 1984 to 1986,Dorothy Denning and Peter Neumann worked out a real-time Intrusion Detection System model--IDES.

In 1990,L.Heberiein and some other people developed NSM(Network Security Monitor),which made a great development of IDS and has formed IDS based on network and IDS based on host computer.

After 1988,America began to study DIDS(Distributed Intrusion Detection System),which became a milestone-product of the history of IDS.

From 1990s to now,the research and development of Intrusion Detection System has made great process in intelligence and distribution.

III.DEFINITION AND WORK-FLOW

A.Definition

Intrusion Detection is the discovery of intrusion behaviors.It collects and analyses the data from some key points in computer networks or computer systems,and checks up whether there exists behaviors violating security policies or attacking signs in networks or systems.Then,it can sound the alarm or make corresponding response in time to ensure the confidentiality and availability of system resource.

B.Work-flow

1)Information Gathering

The first step of intrusion detection is information gathering.And the information include the contents of network traffic,the states and behaviors of the the connection of users and activities.

2)Signal Analysis

For the information gathered above,there are three technologies to analyze them:pattern matching,statistical analysis and integrity analysis.

3)Real-time Recording,Alarming and Limited Counterattack The fundamental goal of IDS is to make corresponding response to the intrusion behaviors,which includes detailed logging,real-time alarm and limited counterattack resource.

IV.G ENERIC M ODEL AND F RAMEWORK

A.The Generic Model

In 1987,Denning proposed a abstract generic model of intrusion detection. In figure 1 below,the model mainly consists of six parts:subjects, objects, audit records,activity profiles,exception records and activity rules.

Intrusion Detection in Network Security

Zhang San 201221xxxx

Master of Computing, xxx xx xx University,Wuhan,China

xxxxxxx@https://www.wendangku.net/doc/4314639224.html,

figure 1

B.The Framework

In recent years,the market of intrusion detection systems develops very quickly,but the lack of the universality of different systems hinders the development of intrusion detection ,because there is no corresponding general standard. In order to solve the universality and coexistence problem between different IDS,America Defense Advanced Research Projects Agency(DARPA) started to make CIDF (Common Intrusion Detection framework ,the common intrusion detection framework) standard,and they tried to provide a fundamental structure which allows intrusion detection,analysis and response system.Finally the security laboratory in the University of California at Davis completed CIDF standard.

The main purpose of the framework is:

1)

IDS component sharing, that is a component of the IDS can be used by another IDS.

2)

Data sharing,that is,all kinds of data in IDS can be shared and transferred between different systems by the standard data format provided.

3)

To improve the universality standards and establish a set of development interface and support tools.

The CIDF expounds the generic model of a intrusion detection system,it will classify a IDS into the components below:

a)Event Generators

Getting events from the whole computing environment and providing them to the other parts of the system.

b)Event Analyzers

Analyzing the data obtained and producing the analytic results.

c)Response Units

It is the functional unit which responses to the analytic results.It can make a strong reaction such as cutting off the connection or changing the attribute of files,or just a simple alarm.

d)Event Databases

It is a collective name of the place where all kinds of data is stored.It can be a complex database or a simple text file.

V.T HE CLASSIFICATION OF INTRUSION.

A.Intrusion Base on the Host

Usually,it makes use of the operating system audit, track log as a data sources,for detecting intrusion,some will also interact with the host system to get the information that doesn’t exist in the system log.This type of detection system does not need additional hardware.It's insensitive to network traffic and have high efficiency,and it can accurately locate the invasion and respond in a timely manner.However,it will occupy the host resources and rely on the reliability of the host.At the same time it can only detect limited types of attacks.Also,it can't detect network attacks.

B.Intrusion Base on the Network

By passively listening to the transmission of the original traffic on the network,it processes the network data and draws useful information from it,and then recognizes attacks by matching with the known attack signatures or being compared with the normal network behavior prototype.Such detection system does not rely on the operating system as detection resources,and can be used to different operating system platforms. It equips with simple configurations and does not need any special auditing and logging mechanism.And it also can detect protocol attacks, the attacks of specific environment and so on.But it only can monitor the activities after the network ,and cannot get the real-time status of the host system which shows its poor accuracy.Most of the intrusion detection tools are based on the network intrusion detection system. C.Di stributed Intrusion

This kind of intrusion detection systems are generally distributed structure, composed of multiple components,which using intrusion detection based on the host on the key hosts while using intrusion detection based on the network on the network key point.At the same time,it analyses the audit log from the host system and the data traffic from network to detect whether a protected system is attacked.

Thees three kinds of intrusion detection systems above have their own advantages and disadvantages,they can complement each other.A complete intrusion detection system (IDS) must be a distributed system based on the host and the network,but at present there is no perfect IDS system as a model.As a matter of fact,the commercial products is rarely based on only a kind of intrusion detection model.The intrusion detection system implemented in different structure and different technique have different advantages and disadvantage ,and each of them can be only used to a particular environment.

VI.THE METHODS OF I NTRUSION D ETECTION

At present,there are many methods of intrusion detection in IDS.There are some common methods below:

A.Statistical Method

The statistical method is a commonly used method of intrusion detection system in production.And it is normally used to Anomaly Detection.The statistical method is a relatively mature intrusion detection method ,it makes the intrusion detection system identify the abnormal activities which are different from the normal activities by learn their main daily behaviors.

B.Expert System

Using the expert system to detect the intrusion is usually aimed at the diagnostic intrusion.The so-called rules,that is

knowledge.the establishment of expert system depends on the Completeness of the knowledge base,and the Completeness of the knowledge base depends on the completeness and real - time of the audit.

C.Keystroke Monitor

Keystroke Monitor is a simple method to detect intrusion by analyzing the pattern of users' keystroke sequence.It can be used to the intrusion detection based on the host.The disadvantages of this technique is very obvious.To begin with,the batch processing or the shell program can directly call attack command sequence instead of keystroke.Secondly,the operating systems generally do not provide keystroke detection interface,so it need extra hook function to monitor the keystrokes.

D.Model-based Method

The attackers often use a certain behavioral sequence in attacking a system such as guessing the password,this kind of behavioral sequence forms a model with a certain behavior syndrome.According to this,it can detect harmless attack attempts.The advantage of this method lies in its sound uncertainty reasoning.Model-based intrusion detection method can monitor only some of the major audit event, after these events,it will start to record detailed audit, so as to reduce the processing load of audit events.

E.Pattern Matching

The intrusion detection method base on pattern matching encodes the known intrusion feature into the pattern which coincides with the audit records.When the new audit event occurs,this method will find the matched intrusion pattern.

VII.I NTRUSION D ETECTION T ECHNOLOGY Intrusion Detection Technology is one of the kernel technologies in security auditing,which is also an important component of the network security protection.There are two main techniques of intrusion Detection--Anomaly Detection and Misuse Detection.

A.Anomaly Detection

Anomaly Detection can be classified into static Anomaly Detection and dynamic Anomaly Detection. Static Anomaly Detection retains a character representation or backup of the static part of the system.When the static part of the system is different from former character representation or backup during a detection, it turns out that the system was attacked.What the dynamic Anomaly Detection aims at is the behavior.A kind of the files which describe the normal behaviors of systems and users should be established before the detection. When the difference between the current behavior and the normal behavior recorded in the files exceeds the predefined standard,it turns out that the system was attacked.

B.Misuse Detection

The following list outlines the different types of graphics published in IEEE journals. They are categorized based on their construction, and use of color / shades of gray:

Misuse Detection is mainly used to detect known measures of attack,which can judge whether the user’s behavior matches with the measure of attacks in the character lib.Obviously,Misuse Detection is of high accuracy.And its shortcomings also because of this feature.With the fast development of attack models,only if we add new models into the character lib can it make the system detect new measures of attack.

VIII.T HE ARCHITECTURE OF INTRUSION DETECTION Throughout the history of the development of intrusion detection technology, the architecture mainly consists of the following several forms:

A.Integrative Structure

In the early development of intrusion detection system,IDS uses mostly single architecture.That is,all the work,including the collection and analysis of the data,are completed on a single host by a single program.The advantage of this technique is that the centralized processing of data makes it more accurate to analyze possible intrusions.The disadvantages is that the centralized processing of data makes the host a bottleneck of network security.When it fails or is attacked,there will be no guarantee for the whole security of network.In addition,this way of data gathering is very difficult to achieve for large network.

The drawbacks of concentrated Intrusion detection system mainly lie in:

1)

Poor expansibility.Processing all the information on a single host limits the scale of monitored network

2)

Hard to reconfigure and add new features.The IDS usually needs to be restarted when it needs to give effect to the new settings and functions .

3)

Central analyzer is a single fail-point.If it is destroyed by invaders,then the whole network will lose the protection.

B.Distributed Structure

With the development of intrusion detection products applied to the enterprises day by day,distributed technology also integrates into the intrusion detection products.This kind of distributed structure uses the method that multiple agents separately detect intrusion in various parts of the network,and process the possible intrusions.Its advantage is that it can monitor data well and detect the internal and external intrusion behavior.But this technology cannot completely solve the shortcomings of the centralized intrusion detection.Since the current network is generally hierarchical structure,but the pure distributed detection requires that the agent distribution should be in the same layer.If the layer is too low,it cannot detect the intrusion aimed at the upper layer.If the layer is too high,it cannot detect the intrusion aimed at the lower layer.At the same time ,since each agent doesn't have the whole cognition of network data,so it cannot accurately judge some certain attacks and is easy to be attacked by attacks aimed at IDS,such as IP

segmentation .

C. L ayered Structure

Because the restriction of single host resources and the distribution of attack information,many detection units should be processed together in high-layer attacks.But the detection unit is generally intelligent agent.Therefore the architecture of recent intrusion detection begins to think about using layered hierarchical to detect intrusion which is becoming more and

more complex,as shown in Figure 2.

Figure 2

In this kind of system,the lowest layer agent is responsible for the collection of all the basic information,and then it simply processes these information and complete simple judgment and processing.Its characteristics are fast speed, high efficiency and large data volume,but it can only detect some simple attacks.The middle layer agent is a link between the one before it and the one after it. On the one hand,it can accept and process the data processed by the lower nodes.On the other hand,it can contact with upper layer,judge and output the results to the upper nodes which enhances the scalability of the system.The top node is mainly responsible for the management and coordination on the whole.In addition,it can dynamically adjust the node layer figure according to the requirement of environment in order to implement the dynamic configuration of the system.

IX. THE DEVELOPMENT DIRECTION OF INTRUSION DETECTION With the rapid development of network technology, intrusion technology also has developed day by day.The switching technology and the data communication through encrypted channels make the methods of network data gathering defective.Moreover the huge traffic brings new requirement for data analysis the development direction of intrusion detection technology mainly include the following: A. Distributed Intrusion Detection Architecture

The traditional IDS is limited to a single host or network

architecture,but for the heterogeneous system and large scale network detection is obviously insufficient,and different IDS systems cannot work together.Therefore, it is necessary to develop distributed intrusion detection architecture.

B. Application Layer Intrusion Detection

Many semantics of intrusion detection only can be understood by the application, but the current IDS can only detect the general protocol such as Web,it can not deal with other application systems such as Lotus Notes, the database system.

C. Intelligent Intrusion Detection

Intrusion methods become more and more diversified and comprehensive,although there are the intelligent body,neural network and genetic algorithm which applied in intrusion detection technology now,but these are just some tentative research work,we still need further research on the Intelligent IDS to improve its abilities.

D. The Auto-protection of Intrusion Detection System

Once the intrusion detection system is controlled by invaders,the security of the whole system will face the danger of collapse.So how to prevent invaders from undermining the functions of intrusion detection system will continue for a long time.

E. The Evaluating Method of Intrusion Detection

The user needs to evaluate many IDSs, the evaluation indexes include the IDS detection range,the occupation of the system resources and the the reliability of itself.Designing the stage for evaluating or testing the IDS to implement the detection of various IDS systems has been called another important research and development field of the current IDS.

X. C ONCLUSION

With the network security issues have become increasingly salient,the development of intrusion detection has greatly increased ,and it has already begun to play a key role in various environments. Predictably, the development of intrusion detection technology has important significance and profound influence for network application.And the future development direction of IDS will be intelligent distributed intrusion detection system.How to develop self - owned intellectual property IDS will become an important task in the field of information security for China.

R EFERENCES

Journal Article:

[1] YanHua Wang,ZhiQiang Ma and Lu Zang,”The Application and

Research of the Intrusion Detection Technologies in Network Security ”. [2] Ran Zhang,”The Research of the Intrusion Detection Technologies ”. [3] Fei Feng,”The Network Security and Intrusion Detection ”.

Reference Website:

https://www.wendangku.net/doc/4314639224.html,/view/20936.htm?adapt=1

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A Preliminary Analysis of the Scienti?c Production of Latin American Computer Science Research Groups Juan F.Delgado-Garcia,Alberto https://www.wendangku.net/doc/4314639224.html,ender and Wagner Meira Jr. Computer Science Department,Federal University of Minas Gerais 31270-901-Belo Horizonte-Brazil {jfdgarcia,laender,meira}@dcc.ufmg.br Abstract.In this paper,we present a preliminary analysis of the sci- enti?c production of Latin American Computer Science research groups. Our analysis is based on data over a period of20years collected from DBLP,and addresses24groups from academic institutions in Argentina, Chile,Colombia,Cuba,Mexico,Peru,Uruguay and Venezuela.Our re- sults show a clear improvement in the publication output of these groups in the last10years,particularly in Argentina,Chile and Mexico. Keywords:Latin America,Computer Science,Scienti?c Production, Coauthorship Analysis,Bibliometrics 1Introduction According to SCIMago Journal and Country Rank(JCR)1,recent years have witnessed a tremendous increase in the scienti?c production in Computer Sci-ence(CS)all over the world.Considering data from2002to2012,for instance,in North America(Canada and USA)the number of publications increased59.73%, in Western Europe(considering only the top-5countries,UK,Germany,France, Italy and Spain)184%,and in Latin American(also considering only the top-5 countries,Brazil,Mexico,Argentina,Chile and Colombia)319%.In other re-gions,countries like Australia,China,Korea,India and Poland have achieved ?gures even higher.Although SCIMago numbers re?ect only publications that appeared in selected journals,they show that CS is a very productive research area with many active research groups spread around the world. In view of this scenario,in this paper we present a preliminary analysis of the scienti?c production of Latin American CS research groups.Our analysis is based on data over a period of20years collected from DBLP2,and addresses 24groups from academic institutions in Argentina,Chile,Colombia,Cuba,Mex-ico,Peru,Uruguay and Venezuela.Despite being the country in Latin America with the highest productivity in the area[4],we have not included Brazil in our analysis for two reasons.First,Brazil is by far the Latin American country 1https://www.wendangku.net/doc/4314639224.html,/countryrank.php 2https://www.wendangku.net/doc/4314639224.html,rmatik.uni-trier.de/~ley/db

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全的脆弱性、计算机病毒等。目前人为攻击和网络本身的缺陷是导致网络不安全的主要因素。 2\计算机网络防范的主要措施 2.1计算机网络安全的防火墙技术 计算机网络安全是指利用网络管理控制和技术措施，保证在一个网络环境里，信息数据的保密性、完整性和可用性受到保护。网络安全防护的根本目的，就是防止计算机网络存储和传输的信息被非法使用、破坏和篡改。 目前主要的网络安全技术有：网络安全技术研究加密、防火墙、入侵检测与防御、和系统隔离等技术。其中防火墙技术是一种行之有效的，对网络攻击进行主动防御和防范，保障计算机网络安全的常用技术和重要手段。 2.2访问与控制策略 对合法用户进行认证可以防止非法用户获得对公司信息系统的访问，使用认证机制可以防止合法用户访问他们无权查看的信息。访问控制策略其任务是保证网络资源不被非法使用和非法访问。各种网络安全策略必须相互配合才能真正起到保护作用，它也是维护网络系统安全、保护网络资源的重要手段，访问控制是保证网络安全最重要的核心策略之一。 (1)入网访问控制。入网访问控制是网络访问的第一层安全机制。控制哪些用户能够登录到服务器并获准使用网络资源，控制用户登录入网的位置、限制用户登录入网的时间、限制用户入网的主机数量。

网络安全现场检测表---入侵检测

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中央广播电视大学 毕业设计（论文） 题目：计算机网络安全分析及防范措施 姓名教育层次 学号专业 指导教师分校

摘要 计算机网络技术是计算机技术与通信技术高度发展、紧密结合的产物，计算机网络对社会生活的方方面面以及社会经济的发展产生了不可估量的影响。当前，世界经济正在从工业经济向知识经济转变，而知识经济的两个重要特点就是信息化和全球化。进入21世纪，网络已成为信息社会的命脉和发展知识经济的重要基础。从其形成和发展的历史来看，计算机网络是伴随着人类社会对信息传递和共享的日益增长的需求而不断进步的。 关键词：计算机技术、网络安全、防范措施

目录 摘要 (2) 目录 (3) 引言 (4) 第一章计算机网络简介 (5) （一）数字语音多媒体三网合一 (5) （二）IPv6协议 (5) 第二章计算机网络安全 (7) （一）网络硬件设施方面 (7) （二）操作系统方面 (7) （三）软件方面 (8) 第三章计算机网络安全以及防范措施 (10) （一）影响安全的主要因素 (10) （二）计算机网络安全防范策略 (11) 第四章结论 (13) 第五章致辞 (14) 第六章参考文献 (15)

引言 计算机网络就是计算机之间通过连接介质互联起来，按照网络协议进行数据通信，实现资源共享的一种组织形式。在如今社会，计算机网络技术日新月异，飞速发展着，计算机网络遍及世界各个角落，应用到各个行业，普及到千家万户；他给我们带来了很多便利，但同时计算机网络故障也让我们烦恼，本此课题主要探讨计算机网络安全。

第一章计算机网络简介 计算机网络技术涉及计算和通信两个领域，计算机网络正是计算机强大的计算能力和通信系统的远距离传输能力相结合的产物。从20世纪70年代以主机为中心的主机——终端模式，到20世纪80年代客户机/服务器、基于多种协议的局域网方式，再到现在以Internet TCP/IP 协议为基础的网络计算模式，短短的30多年间，计算机网络技术得到了迅猛的发展，全世界的计算机都连接在一起，任何人在任何地方、任何时间都可以共享全人类所共有的资源。20世纪90年代后，Internet的广泛应用和各种热点技术的研究与不断发展，使计算机网络发展到了一个新的阶段。 （一）数字语音多媒体三网合一 目前，计算机网络与通信技术应用发展的突出特点之一是要实现三网合一。所谓三网合一就是将计算机网、有线电视网和电信网有机融合起来，以降低成本，方便使用，提高效率，增加经济效益和社会效益。 三网合一是网络发展的必然趋势。Internet的出现造就了一个庞大的产业，同时推动了其它相关产业的发展。一些新兴业务如电子商务、电子政务、电子科学、远程教学、远程医疗、视频会议和在线咨询等，使人们能突破时间和空间的限制，坐在家中就可以工作、学习和娱乐。 （二）IPv6协议 IP协议开发于上个世纪70年代，并逐步发展成为今天广泛使用的IPv4。不可置疑，它是一个巨大的成功，在过去的20多年中，被认为是一项伟大的创举。但是日益增长的对多种服务质量业务的要求——尤其是安全性和实时性的要求，已经使得Internet不堪重负，而IPv4的不足也日益明显地显现出来。具体表现在以下几个方面：

计算机专业毕业设计论文(C++)外文文献中英文翻译(Object)[1]

外文资料 Object landscapes and lifetimes Technically, OOP is just about abstract data typing, inheritance, and polymorphism, but other issues can be at least as important. The remainder of this section will cover these issues. One of the most important factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object controlled? There are different philosophies at work here. C++ takes the approach that control of efficiency is the most important issue, so it gives the programmer a choice. For maximum run-time speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocation and release, and control of these can be very valuable in some situations. However, you sacrifice flexibility because you must know the exact quantity, lifetime, and type of objects while you're writing the program. If you are trying to solve a more general problem such as computer-aided design, warehouse management, or air-traffic control, this is too restrictive. The second approach is to create objects dynamically in a pool of memory called the heap. In this approach, you don't know until run-time how many objects you need, what their lifetime is, or what their exact type is. Those are determined at the spur of the moment while the program is running. If you need a new object, you simply make it on the heap at the point that you need it. Because the storage is managed dynamically, at run-time, the amount of time required to allocate storage on the heap is significantly longer than the time to create storage on the stack. (Creating storage on the stack is often a single assembly instruction to move the stack pointer down, and another to move it back up.) The dynamic approach makes the generally logical assumption that objects tend to be complicated, so the extra overhead of finding storage and releasing that storage will not have an important impact on the creation of an object. In addition, the greater flexibility is essential to solve the general

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第9卷第2期浙江工贸职业技术学院学报V ol.9 No.2 2009年6月JOURNAL OF ZHEJIANG INDUSTRY&TRADE VOCATIONAL COLLEGE Jun.2009 【安全生产】入侵检测技术和防火墙结合的网络安全探讨 xxxx年xx月xx日 xxxxxxxx集团企业有限公司 Please enter your company's name and contentv

入侵检测技术和防火墙结合的网络安全探讨 陈珊陈哲* （浙江工贸职业技术学院，温州科技职业学院，浙江温州325000） 摘要：本文指出了目前校园网络安全屏障技术存在的问题，重点分析了IDS与防火墙结合互动构建校园网络安全体系的技术优势，并对IDS与防火墙的接口设计进行了分析研究。 关键词：防火墙；网络安全；入侵检测 中图文分号：TP309 文献标识码：A文章编号：1672－0105（2009）02－0061－05 The Discussion of Security Defence Based on IDS and Firewall Chen Shan, Chen Zhe (Zhejiang Industrial＆Trade Polytechnic, Wenzhou Science and Technology Vocaitional College，Wenzhou Zhejiang 325000) Abstract: This essay points out the problem in current security defence technology of campus network, which focuses on the technology advantages of combine and interaction of firewall and IDS (Intrusion Detection System) to build 120 campus network security system, and it also analyses and studies the interface design of firewall and IDS. Key Words: Firewall; Network Security; IDS (Intrusion Detection Systems) 随着国际互联网技术的迅速发展，校园网络在我们的校园管理、日常教学等方面正扮演着越来越重要的角色，为了保护学校内部的机密信息(如人事安排、档案、在研课题、专利、纪检报告等)，保证用户正常访问，不受网络黑客的攻击，病毒的传播，校园网必须加筑安全屏障，因此，在现有的技术条件下，如何构建相对可靠的校园网络安全体系，就成了校园网络管理人员的一个重要课题。 一、目前校园网络安全屏障技术存在的问题 一）防火墙技术的的缺陷 防火墙技术是建立在现代通信网络技术和信息安全技术基础上的应用性安全技术，它越来越多被地应用于校园网的互联环境中。是位于两个信任程度不同的网络之间(如校园网与Internet之间)的软件或硬件设备的组合，它对网络之间的通信进行控制，通过强制实施统一的安全策略，防止对重要信息资源的非法存取和访问以达到保护系统安全的目的。但也必须看到，作为一种周边安全机制，防火墙无法监控内部网络，仅能在应用层或网络层进行访问控制，无法保证信息(即通信内容)安全，有些安全威胁是 *收稿日期：2009-3-9 作者简介：陈珊（1975- ），女，讲师，研究方向：计算机科学。

计算机网络安全论文

一、绪论 计算机诞生之初功能较为单一，数据处理相对简单，而随着计算机网络技术的发展，计算机功能的多样化与信息处理的复杂程度显著提高。网络的出现，将过去时间与空间相对独立和分散的信息集成起来，构成庞大的数据信息资源系统，为人们提供更加便捷化的信息处理与使用方式，极大的推动了信息化时代的发展进程。然而，随之而来的是这些信息数据的安全问题，公开化的网络平台为非法入侵者提供了可乘之机，不但会对重要的信息资源造成损坏，同时也会给整个网络带来相当大的安全隐患。因此，计算机网络安全问题成为当今最为热门的焦点之一，随着网络技术的发展，安全防范措施也在不断更新。 二、计算机安全的定义 国际标准化组织（ISO）将“计算机安全”定义为：“为数据处理系统建立和采取的技术和管理的安全保护，保护计算机硬件、软件数据不因偶然和恶意的原因而遭到破坏、更改和泄漏”。上述计算机安全的定义包含物理安全和逻辑安全两方面的内容，其逻辑安全的内容可理解为我们常说的信息安全，是指对信息的保密性、完整性和可用性的保护，而网络安全性的含义是信息安全的引申，即网络安全是对网络信息保密性、完整性和可用性的保护。 三、影响计算机网络安全的主要因素 1、网络系统本身的问题 目前流行的许多操作系统均存在网络安全漏洞，如UNIX,MS NT 和Windows。黑客往往就是利用这些操作系统本身所存在的安全漏洞侵入系统。具体包括以下几个方面：稳定性和可扩充性；网络硬件的配置不协调；缺乏安全策略；许多站点在防火墙配置上无意识地扩大了访问权限，忽视了这些权限可能会被其他人员滥用；访问控制配置的复杂性，容易导致配置错误，从而给他人以可乘之机； 2、来自内部网用户的安全威胁 来自内部用户的安全威胁远大于外部网用户的安全威胁，使用者缺乏安全意识，许多应用服务系统在访问控制及安全通信方面考虑较少，并且，如果系统设置错误，很容易造成损失，管理制度不健全，网络管理、维护任在一个安全设计充分的网络中，人为因素造成的安全漏洞无疑是整个网络安全性的最大隐患。网络管理员或网络用户都拥有相应的权限,利用这些权限破坏网络安全的隐患也是存在的。如操作口令的泄漏,磁盘上的机密文件被人利用，临时文件未及时删除而被窃取，内部人员有意无意的泄漏给黑客带来可乘之机等，都可能使网络安全机制形同虚设。其自然。特别是一些安装了防火墙的网络系统，对内部网用户来说一点作用也不起。 3、缺乏有效的手段监视、硬件设备的正确使用及评估网络系统的安全性 完整准确的安全评估是黑客入侵防范体系的基础。它对现有或将要构建的整个网络的安全防护性能作出科学、准确的分析评估，并保障将要实施的安全策略技术上的可实现性、经济上的可行性和组织上的可执行性。网络安全评估分析就是对网络进行检查，查找其中是否有可被黑客利用的漏洞，对系统安全状况进行评估、分析，并对发现的问题提出建议从而提高网络系统安全性能的过程。评估分析技术是一种非常行之有效的安全技术