Abstract- With the rapid development of computer network technology, the security of computer network becomes increasingly important. Three main threats facing computer network security include: hackers, computer virus and denial of service attack. Things leading to the safety of the network are mainly: resources sharing, data communication, computer virus and TCP/IP protocol security flaws. A safety network system should include at least three kinds of measures: legal measures, technical measures and review and management measures. The paper analyzes the main threat facing computer network security, discusses network security technology and advances some effective countermeasures in view of the hidden danger of current common network security.
Keywords-network security; computer network; information security; security strategy; prevention strategy
I. INTRODUCTION
With the development of Internet technology, computer network gradually changes people's life and way of work. In the process of rapid popularization of computer network, hidden dangers of computer security become increasingly prominent. This requires us take strong measures to ensure the safety of the network. The computer network security refers to the use of network management to control and technical measures to ensure data privacy in a network environment. But as computer network is open, sharing and international, it makes computer network more vulnerable. In order to
solve this problem, now people mainly research in the field of data encryption technology, identity authentication, firewall, network management and that sort of things[ l].
AI. CONCEPT OF COMPUTER NETWORK SECURITY
The computer network security refers to the use of network management to control and technical measures to ensure that in a network environment, the data privacy, integrity and availability can be protected. The computer network security includes two aspects: physical security and logic security. The physical security system means that equipment and related facilities are protected from destruction, loss, etc. Logic security includes the integrity of information, secrecy and availability. The meaning of computer network security varies from users to users. Different users have different understanding of network safety requirements. To general users who may just want
individual privacy or confidential information on the network transmission to be protected and to avoid being eavesdropping, tampering and forge. But for network providers, they not only care about the network information safety, but also consider how to cope with sudden natural disasters, such as a military strike to network hardware damage, as well as how to restore network communication and maintain the continuity of network communication in abnormal situations.
Essentially, network security include hardware that compose network system, software and its transfer over a network information safety, which protected it from accidental or malicious attack, network security concerns both technical problems and management issues, which are in complement with each other.
BI. MAJOR THREATS OF COMPUTER NETWORK
A. Internal interception and Destruction
The people inside of network system may become the following possible threats: internal confidential personnel's intentionally or unintentionally leaks, the change of the record information; internal unauthorized personnel's intentionally or not, stealing confidential information, change the network configuration and record information; network system damage from Internal personnel.
B. Unauthorized Access
Unauthorized access refers to the unauthorized use of network resources or unauthorized ways to use the network resources. It includes illegal users' hacking into the network or illegal operation system, and legitimate users' unauthorized way of operation.
C. Damage the Integrity of Information
Attackers may damage the information integrity from three aspects: changing the order of the information flow, timing, changing the content, the form of information; Deleting news or some of the news; and Inserting some information in the news, making the receiver not able to read or receive the wrong information[2].
D. Interception
Through the wiretapping or the electromagnetic wave radiation within the scope of the installation, the attacker may intercept confidential information, or through to the information flow, communication frequency and length of
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the parameters find out useful information. It does not damage the transfer information, and it is not easy examinable.
E. Pretending
The attacker may pretend to do the following: pretend to be leadership issue orders and read the documents; Pretend to be host deceive legitimate hosts and legitimate users. Pretend to be network control program to show or modify the access to key information, passwords, etc, excessive use of network equipment and resources: take over a legitimate user, cheat the system, take up the resources of the legitimate users.
F. Destroy System Availability.
The attacker may damage from the following aspects of network system availability: making a legitimate user not able to have normal access to the network resources; Making a strict time required service not able to get the timely response and destroy system.
G. Repeat Itself
Repeat itself refers that the attacker intercepted and record information, and then send these information repeatedly when necessary.
H. Denial
Possible denials are the sender's later denial of sending a piece of news content; the receiver later denied that he had received a message earlier.
1. Other Threats
The threats of network system also include computer virus, electromagnetic leakage, all kinds of disasters, and the operating error, etc.
IV. PROTECTIVE MEASURES OF COMPUTER NETWORK
SECURITY
A. Technical Level Countermeasures
From technical level computer network security technology mainly include real-time scanning technology, real-time monitoring technology, firewall, completeness inspection protection technology, virus situation analysis report technology and system security management technology. The technical level can take the following measures:
1) Establish a system of safety management
Improve the quality of stuff including system administrators and technical personnel professional and users. To the important department and information, strictly inspect virus in computer boot, backup data in time, which is a simple and effective method.
2) Network access control
Access control is the main strategy of network security and protection. Its main task is to guarantee that the network resources are protected from illegal use and access. It is one of the most important strategies of network security. The technology of access control involves many things such as
network access control, directory level control and attributes control[3].
3) Database backup and recovery.
Database backup and recovery is the important operation of database administrators to maintain data security and integrity. Restore database backup is the easiest and can prevent most accident. Recovery refers to the operation of using backup to restore data after accident. There are three main backup strategies: only backing up the database, backing up the database and affairs log and incremental backup.
4) Application code technology
Application code technology is the core technology of information security. Information security password is to provide a reliable guarantee. Based on code of digital signatures and identity authentication to guarantee that the main method of information integrity, one of which include classical code techniques, single key code system, public key code system, digital signature and key management.
5) Cuting off the transmission way
Carry on a thorough antivirus examination on affected hard disk and the computer, don't use the unexplained USB disk and the program, don't download SUSpICIOUS information.
6) Improve anti-virus technology of network
By installing virus firewall, real-time filtering IS conducted. The files server on the network should be frequently scanned and monitored, using anti-virus software in the work site, strengthening the network directory and file access settings[4].
7) Conduct research and development to improve the operation of the high quality security system.
Research and develop high security operating system, and don't give the virus hotbed to live, which would make computer network safer.
B. Management Level Countermeasures
The computer network security management not only depends on the security technology and preventive measures, but also depends on the management measures it takes and the protection laws and regulations it implements. Only by linking them closely can we make the computer network security really effective.
The computer network security management includes educating users of computer safety, and setting up corresponding security management institution, continuous improvement and strengthening the management function, strengthen works on computer and network of the legislation and law enforcement, etc. Strengthen computer security management and enhance the user of the laws, regulations and moral concepts, improve computer users' awareness of safety, to prevent the computer crime and resistance to the hacker attacks and prevent computer virus interference, are all very important measures.
This means the ongoing legal education on computer users, including computer security law, code, data and so on, make the right and obligation clearly to computer users and systems management personnel, consciously abide by the legal information system principle, legal principle, the
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principle of public information, information use principle and resource constraints principle. Consciously fight against all the behavior of the illegal crime, maintain the safety of the computer and network system, and the safety of the information system. In addition, we still should educate computer users and the staff, and obey all the rules and regulations set up for maintenance system safety, including personnel management system, operation maintenance and management system, computer processing control and management system, all kinds of material management system, computer room management system, special plane to defend the special division of work and strict management system.
C. Physical Security Level Countermeasures
To ensure the safety of computer network system's reliability we must ensure that there is a security system entity of the physical environment conditions. The safe environment refers to computer room and its facilities, mainly include the following content:
1) Computer system environment conditions
The computer system security environment conditions include temperature, humidity, air cleanliness, corrosion degrees, insect, vibration and impact, electrical disturbance and so on, which all have specific requirement and strict standards.
2)Computer room environment selection
control to identifY users' identity, and to verifY its validity; Secondly, visitors must define the scope of activities; Thirdly, multilayer safe protection should be set in the center of computer system to prevent illegal invasion of violence; Fourthly, buildings where equipment is located shall have equipment to protect against all kinds of natural disasters.
V. CONCLUSION
The computer network security is a complicated system of engineering, involving technology, equipment, management, system and so on, and security solutions should be set and understood from the whole. Network security solution is a combination of various security technologies in computer network information system, one that combines safe operating system technology, firewall technology, virus protection technology, intrusion detection technology, and security scanning technology, which forms a complete set of network safety protection system. We must make sure that management and technology, safety technology be integrated with safety measures, and strengthen the computer legislation and enforcement of law, establish backup and recovery mechanism, make corresponding safety standards, and strengthen the network security management measures. Only in this way can we ensure the security of the computer network.
REFERENCES
The choosing of a suitable installation place for computer system is very important which directly affect the reliability and safety of the system. When choosing a computer room, we should pay attention to its external environment safety, reliability, avoid strong vibration sources and strong noise source, and avoid high buildings and water in the lower equipment or the next door. The management of the entrance should also be noted[5].
3) Computer room safety protection
The computer room security protection is designed for the physical environment and to prevent disaster from unauthorized individuals or group damage, tampering or theft of network facilities, important data and take security measures and countermeasures. In order to manage regional security, first of all, we should consider the physical access
摘要——随着计算机网络技术的快速发展,计算机网络的安全变得越来越重要。计算机网络安全所面临的三个主要威胁包括:黑客、计算机病毒和分布式拒绝服务攻击（也称为洪水攻击）。导致网络安全的主要因素是:资源共享、数据通信、计算机病毒和TCP / IP协议的安全缺陷。一个安全的网络系统至少应该包括三种安全措施:法律措施、技术措施和审查管理措施。本文主要分析了计算机网络安全所面临的主要威胁,探讨了网络安全技术并针对当前常见的网络安全隐患提出了有效的对策。
关键词-网络安全;计算机网络;信息安全;安全战略;预防策略
Ⅰ.引言
随着互联网技术的发展,计算机网络逐渐改变人们的生活和工作方式。当然，伴随着计算机网络的迅速普及,计算机网络的安全隐患也日益突显。这就需要我们采取有力的措施来确保网络的安全。计算机网络安全是指利用网络管理控制和技术措施,确保个人数据在网络环境中的安全系数。但是计算机网络具有开放性,共享性和国际性,这使得计算机网络更容易受到攻击。为了解决这个问题,现在人们在这个领域研究的主要项目是数据加密技术、身份认证、防火墙、网络管理和诸如此类的技术[l]。
Ⅱ.计算机网络安全的概念
计算机网络安全是指利用网络管理控制和技术措施,保证在网络环境中,个人数据和数据的完整性和可用性可以受到保护。计算机网络安全包括两个方面:物理安全和逻辑安全。物理系统安全是指设备和相关设施免受破坏损失等方面。逻辑安全是指信息的完整性、保密性和可用性。计算机网络安全对不同的用户有不同的含义，对安全程度的要求也不尽相同。一般用户可能只是希望个人隐私或机密信息在网络上受到保护,避免被窃听、篡改和伪造。但是对于网络提供商来说,他们不仅仅关心网络信息安全,而且要考虑如何应对突发性自然灾害,比如军事打击网络硬件损坏,以及如何在异常情况下恢复网络通
信和维护网络通信的连续性。
归根结底，网络安全包括组成网络系统的硬件、软件及信息在网络中传输的安全,要防止它们意外损坏或恶意攻击,需要网络技术和管理措施相辅相成，共同作用。
Ⅲ.计算机网络的主要威胁
A .内部窃听和破坏
网络系统内部工作人员可能存在如下安全威胁:内部机密人员的故意或无意泄漏,记录信息的变化,内部未经授权人员的故意或无意窃取机密信息,更改网络配置和记录信息; 内部人员对网络系统的破坏。
B .未经授权的访问
网络资源的未经授权的访问是指未经授权使用网络资源或使用未经授权的方式使用网络资源。它包括非法用户的入侵网络或非法操作系统以及合法用户的非法操作的方式。
C .破坏信息的完整性
攻击者可能从三个方面损坏信息的完整性:改变信息流的顺序、时间、更改内容；更改信息的形式；删除全部信息或部分信息,和插入部分信息,使接收机无法接收或接收到错误的信息。
D .信息拦截
攻击者通过在信息通过的范围内安装窃听器或电磁波辐射装置来获取重要信息,他们可能会直接获取机密信息,或者通过信息流,通信的频率和长度等参数找出有用的信息。这种方式不损害传输的信息,不容易被发现。
E .骗取信息
攻击者可能会假装做以下的事情来获取信息:假装上级发号施令来读取有用文件;假装合法主机通过主机欺骗合法用户。假装网络控制程序来显示或修改关键信息,密码等,通过过度使用网络设备和资源，接管一个合法用户,干扰用户系统来获取合法用户的资源。
F .破坏系统可用性。
攻击者可能从以下方面损坏网络系统的可用性:破坏系统
使合法用户不能正常访问网络资源,使进程不能得到及时的响应并且破坏系统。
G .复制信息
复制信息是指攻击者截获并记录信息,然后在必要的时候运用这些信息。
H .否认
可能的否认是发送方稍后将否认发送一则消息内容;或者接收者后来否认他收到过一个消息。
I .其他威胁
网络系统隐患还包括计算机病毒的威胁,电磁波泄漏,各种各样的灾难和操作错误等。
Ⅳ.计算机网络的安全保护措施
安全
A .技术层面的措施
从技术水平方面来讲，计算机网络安全技术主要有实时扫描技术、实时监控技术,防火墙,完整性检查保护技术、病毒情况分析报告技术和系统安全管理技术。技术层面可以采取以下措施:
1)建立安全管理制度
提高系统管理员和专业技术人员和用户的素质。计算机的重要部件和信息,在每次电脑启动时严格进行病毒扫描,及时备份数据,这是一个简单而有效的方法。
2)网络访问控制
访问控制是网络安全的主要策略和保护方法。其主要任务是保证网络资源免受非法使用和访问。这是网络安全最重要的战略之一。访问控制涉及网络访问控制、目录级别控制和属性控制等多项技术。
3)数据库备份和恢复
数据库备份和恢复是数据库管理员为了维护数据的安全性和完整性所采取的重要举措。恢复数据库备份是最简单也是最能防止错误发生的方法。恢复是指发生错误后使用备份来恢复数据。主要有三种备份策略:只备份数据库,数据库和事务日志
备份和增量备份。
4)应用程序代码技术
应用程序代码技术是信息安全的核心技术。信息安全密码是给安全提供可靠的保证一种方法。基于代码的数字签名和身份认证等技术,保证信息完整性的主要方法有经典代码技术,单一关键代码系统,公钥密码系统,数字签名和密钥管理等。
5)切断传播途径
对硬盘和电脑进行全面检查并进行杀毒，不使用原因不明的USB、磁盘，不要下载可疑的信息。
6)改善网络反病毒技术
通过安装病毒防火墙,实时进行过滤。文件服务器在网络上应该经常扫描和监控, 在工作网站使用杀毒软件,加强网络目录和文件访问设置。
7)研究和开发高质量保障体系
研究和开发高安全操作系统,不给病毒制造温床,这将会使计算机网络更加安全。
B .管理水平的对策
计算机网络安全管理不仅取决于安全技术和预防措施,它的实现还取决于所需的管理措施和法律法规的保护。只有两者紧密结合,才能使计算机网络安全真正有效。
计算机网络安全管理包括用户的计算机安全教育,并建立相应的安全管理机构,不断改进和加强管理职能,加强计算机及网络工作的立法和执法等。加强计算机安全管理,增强用户的法律、法规和道德观念,提高计算机用户的安全意识,防止黑客攻击，防止计算机犯罪，防止计算机病毒干扰,都是非常重要的措施。
这意味着计算机安全法律、代码、数据等法律教育在计算机用户中应当持续进行 ,使计算机用户和系统管理人员的权利和义务更加明确，使其自觉遵守法律信息系统原则、法律原则,公共信息的原则,信息使用原则和资源约束原则。有意识地打击违法犯罪的行为,维护计算机和网络系统的安全，以及信息系统的安全。此外,我们还应当教育计算机用户和员工遵守
所有的规则和规定，为维护系统安全,包括人事管理系统,操作维护和管理系统,计算机处理控制和管理系统,各种各样的材料管理系统,机房管理系统, 设置专机保护的特殊分工和严格的管理系统。
C .物理安全层面的措施
为确保计算机网络系统的安全,我们必须确保有一个安全系统实体的物理环境条件。安全的环境是指计算机机房及其设施,主要包括以下内容:
1） 计算机系统环境条件
计算机系统安全环境条件包括温度、湿度、空气清洁度、腐蚀度,昆虫,振动和冲击,电子干扰等等,每项都有具体的要求和严格的标准。
2)机房环境的选择
对计算机系统来说，选择合适的安装位置是非常重要的，这直接影响到系统的可靠性和安全性。选择机房时,我们应该注意它的外部环境的安全性和可靠性,避免强烈的振动源和强噪声源,并避免高层建筑和隔壁或地面潮湿的地方。入口的管理也应该明确说明。
3)机房安全保护
机房安全保护要根据实际情况设计，防止未经授权的个人或组织损伤,篡改或窃取网络设施、重要数据，当有此类事情发生时，采取相应的安全措施和对策。为了管理地区安全,首先,我们应该考虑通过物理访问控制来识别用户的身份,并验证其有效性;其次,必须给游客定义活动范围;第三,多层安全防护，应设置中心计算机系统来防止非法暴力入侵;第四,建筑设备所在地必须有设备来防止各种各样的自然灾害。
Ⅴ.结论
计算机网络安全是一项复杂的系统工程,涉及技术、设备、管理、系统等方面，安全解决方案应该考虑整个系统而设计。网络安全解决方案综合了各种计算机网络信息系统安全技术,将安全操作系统技术、防火墙技术、病毒防护技术、入侵检测技术、安全扫描技术相结合,形成的一套完整的网络安全