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Unit 3 Network Security and Authentication

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Unit 3 Network Security and Authentication Information Security UNIT 3 NETWORK SECURITY AND AUTHENTICATION Structure 3.0 Introduction 3.1 Objectives 3.2 Meaning of Network Security 3.3 Threats to Network Security 3.4 Comparison with Computer security 3.5 Security Issues for Small and Medium Sized Businesses 3.6 Tools for network Security 3.7 Elements of Network Security 3.8 Secure Network Devices 3.9 Significance of Network Layout in Network Security 3.10 Summary 3.11 Solutions/Answer 3.12 References/Further Readings 3.0INTRODUCTION The previous two units discussed about the fundamentals of information as well as network security issues which lead to different kinds of problem: attacks, theft of essential information and software vulnerabilities. In this unit, we shall learn about how to build a secure network. We shall also learn about the various parameters which must be considered for network security. There can be various security issues involved in small and medium sized businesses which require utmost attention for creating the secure network. Then we shall be covering different kind of tools available for network security, critical elements of network security like Firewall, password mechanisms, encryption, authentication & integrity etc. Lastly, we shall study about some secure network devices like secure modems. Let's first study the basics of network and network security. 3.1OBJECTIVES After going through this unit, you should be able to: • understand the scope of network security; • understand the various kind of threats to any network; • understand Denial of Service attack and its counter measures; • compare Network security with Computer security; • understand the challenges to any business environment regarding the network; • understand different security issues involved with small and medium sized businesses; • understand the application of network security tools; • understand firewall and its types; • understand the password aging and password policy enforcement?; • understand the basics of secure network devices; and 42 Information Security • understand the importance of network layout in network security; and 3.2 WHAT IS NETWORK SECURITY Let us first revisit the concept of network. A computer network is simply a system of interconnected computers. That is used every day to conduct transactions and communications among businesses, government agencies and individuals. The networks consist of "nodes", which are "client" terminals (individual user PCs), and one or more "servers" and/or "host" computers. They are linked by communication systems, some of which might be private, such as within a company and others which might be open to public access. The obvious example of a network system that is open to public access is the Internet, but many private networks also utilize publicly- accessible communications. Today, most companies© host computers which can be accessed by their employees whether in their offices over a private communications network, or from their homes or hotel rooms while on the road through normal telephone lines. Hence, security plays a crucial role in that. Now, let us understand the concept of Network Security. Network security comprises the measures a company takes to protect its computer system and it is a prime concern for every company which uses computers. Compromised network security means a hacker or competitor may gain access to critical or sensitive data, possibly resulting in data loss, or even complete destruction of the system. Network security involves all activities that organizations, enterprises, and institutions undertake to protect the value and ongoing usability of assets and the integrity and continuity of operations. An effective network security strategy requires identifying threats, risks and vulnerabilities and then choosing the most effective set of tools to combat them. 3.3THREATS TO NETWORK SECURITY There are various threats identified for network security. Let us discuss few of them in brief: Viruses: Computer programs written by devious programmers and designed to replicate themselves and infect computers when triggered by a specific event. Viruses reproduce themselves by attaching themselves to other files that the user does not realize are infected. Viruses spread today mainly through E-mail attachments. The attachment may be a file that is a legitimate file but the virus may be attached as a macro program in the file. An example is a Microsoft word file. These files can contain macro programs which can be run by Microsoft Word. A virus may infect these files as a macro and when they get on the next user©s computer, they can infect other files. These virus programs normally take advantage of a security vulnerability of the running application. Viruses can directly affect executable files or Dynamic Link Library (DLL) files that the operating systems and applications use to run. Usually the virus will spread before it will do anything that may alert the user of its presence. Unauthorized Access 43 ªUnauthorized access©º is a very high-level term that can refer to a number of different Network Security and sorts of attacks. The goal of these attacks is to access some resource that your machine Authentication should not provide the attacker. Trojan Horse Programs Trojan horse software is the software that appears to have some useful function, but some hidden purpose awaits inside. This purpose may be to send sensitive information from inside your organization to the author of the software. To prevent Trojan horse programs from infiltrating your organization is to implement the countermeasures. Allowing only approved software with proper testing to be run in the organization will minimize the threat of these programs. The organizational security policy can help ensure that all members of the organization operate in compliance with this countermeasure. Data interception: It involves eavesdropping on communications or altering data packets being transmitted. Social engineering: Social engineering is concerned with obtaining confidential network security information through no technical means, such as posing as a technical support person and asking for people©s passwords. DoS (Denial-of-Service) Attacks DoS (Denial-of-Service) attacks are probably the nastiest, and most difficult to address. These are the nastiest, because they©re very easy to launch, difficult (sometimes impossible) to track, and it isn©t easy to refuse the requests of the attacker, without also refusing legitimate requests for service. The premise of a DoS attack is simple: send more requests to the machine than it can handle. 3.4 COMPARISON WITH COMPUTER SECURITY When the term computer security is used, it specifically refers to the security of one computer, although the overall security of each individual computer is required for network security. When the term network security is used, it refers to the security of the network in general. This includes such issues as password security, network sniffing, intrusion detection, firewalls, network structure and so forth. Securing network infrastructure is like securing possible entry points of attacks on a country by deploying appropriate defense. Computer security is more like providing means to protect a single PC against outside intrusion. The former is better and practical to protect the civilians from getting exposed to the attacks. The preventive measures attempt to secure the access to individual computers--the network itself-- thereby protecting the computers and other shared resources such as printers, network- attached storage connected by the network. Attacks could be stopped at their entry points before they spread. As opposed to this, in computer security the measures taken are focused on securing individual computer hosts. A computer host whose security is compromised is likely to infect other hosts connected to a potentially unsecured network. A computer host©s security is vulnerable to users with higher access privileges to those hosts. 3.5 SECURITY ISSUES FOR SMALL AND MEDIUM- SIZED BUSINESSES 44 Information Security Small and medium-sized businesses use the Internet and networked applications to reach new customers and serve their existing ones more effectively. At the same time, new security threats and legislation puts increased pressure on business networks to be reliable and secure. Business Challenges According to recent studies, security is the biggest challenge facing small and medium-sized businesses. Ever-changing security threats from both inside and outside the business network can wreak havoc on business operations, affecting profitability and customer satisfaction. Small and medium-sized businesses must also comply with new regulations and laws created to protect consumer privacy and secure electronic information. Security issues for small and medium ± sized businesses are classified into 5 basic categories: Worms and Viruses As per research, Computer worms and viruses remain the most common security threat, with 75 percent of small and medium businesses affected by it.. Worms and viruses can have a devastating effect on business continuity and the bottom line. Smarter, more destructive strains are spreading faster than ever, infecting an entire office in seconds. Cleaning the infected computers takes much longer. The catastrophic results are lost orders, corrupted databases and angry customers. As businesses struggle to update their computers with the latest operating system patches and antivirus software, new viruses can penetrate their defenses any day
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