Computer Network Security

Ali Sadiqui

• Publisher: Wiley-ISTE
• Year: 2020
• Print ISBN: 9781786305275
• eBook ISBN: 9781119706724
• Edition: 1
• Topic: Computer Science
• Subtopic: Computer Engineering
• Index: Computer Science

Developed in collaboration with a training and certification team from Cisco, Computer Network Security is an exploration of the state-of-the-art and good practices in setting up a secure computer system. Concrete examples are offered in each chapter, to help the reader to master the concept and apply the security configuration.

This book is intended for students preparing for the CCNA Security Exam (210-260 IINS)? whether at professional training centers, technical faculties, or training centers associated with the Cisco Academy program. It is also relevant to anyone interested in computer security, be they professionals in this field or users who want to identify the threats and vulnerabilities of a network to ensure better security.

1
Fundamentals of Network Security

This chapter studies the following subjects:

• – the chief objectives of securing a network;
• – information security terminology:
  • - general terminology,
  • - types of hackers,
  • - malicious codes;
• – the types of network security:
  • - physical security,
  • - logical security,
  • - administrative security;
• – the chief risks related to the logical security of a network:
  • - the different kinds of network attacks,
  • - measures for network security,
  • - vulnerability audit measures

1.1. Introduction

Network security is the branch of computer science that consists of protecting all components of a computer network in order to prevent unauthorized access, data stealing, misuse of a network connection, modification of data, etc. The aim of network security is to provide proactive defense methods and mechanisms to protect a network against internal and external threats.

1.1.1. The main objectives of securing a network

The three main objectives in securing a network are to ensure:

• – confidentiality: this consists of protecting data stored on or traveling over a computer network from unauthorized persons;
• – integrity: this maintains or ensures the reliability of data. The data received by a recipient must be identical to the data transmitted by the sender;
• – availability: this ensures that network data or services are constantly accessible to users.

1.1.2. Information security terminology

1.1.2.1. General terminology

• – A resource: any object that has value for an organization and must be protected.
• – A vulnerability: a weakness in a system, which may be exploited by a threat.
• – A threat: a potential danger to a resource or to the functioning of a network.
• – An attack: this is an action carried out to harm a resource.
• – A risk: the possibility of an organization’s resource being lost, modified, destroyed or suffering other negative consequences. The risk may arise from a single threat or several threats or the exploitation of a vulnerability:
  A risk = a resource + a threat + a vulnerability
• – A countermeasure: protection that mitigates a potential threat or a risk.

1.1.2.2. Types of hackers

There are different kinds of hackers in the field of information technology:

• – “hackers”: this group is defined as people who are “network maniacs” and only wish to understand the working of computer systems, while also testing their own knowledge and tools;
• – “white hat hackers”: these are individuals who carry out safety audits in order to test that an organization’s computer networks are well-protected;
• – “black hat hackers”: these are experienced individuals who work towards illegal ends by carrying out data theft, hacking accounts, infiltrating systems etc.;
• – “gray hat hackers”: individuals who are a mix of a “white hat” and “black hat” hackers;
• – “blue hat hackers”: these are individuals who test bugs in order to ensure that applications work smoothly;
• – “script-kiddies”: these are individuals with very basic IT security management skills and who try to infiltrate systems using scripts and programs developed by others;
• – “hacktivists”: these are individuals who are chiefly driven by ideological motives;
• – “phreakers”: these are individuals who are specialized in attacking telephonic systems. In general, they work towards placing free calls;
• – “carders”: these are individuals who specialize in attacking smart card systems.

1.1.2.3. Malicious codes

The most common types of malicious codes or malware that may be used by hackers are:

• – virus: this is a program that attaches itself to a software to carry out a specific, undesirable function on a computer. Most viruses need to be activated by the user. However, they can also be set to “idle mode” for prolonged periods as they can also be programmed to avoid detection;
• – worms: these are independent programs that exploit known vulnerabilities with the aim of slowing down a network. They do not need to be activated by the user, and they can duplicate themselves and attempt to infect other hosts in the network;
• – spyware: these are spy software that are generally used in order to influence the user, to buy certain products or services. Spyware is not usually aut...

Table of contents

• Cover
• Table of Contents
• Preface
• Introduction
• 1 Fundamentals of Network Security
• 2 Securing Network Devices
• 3 Supervising a Computer Network
• 4 Securing Access Using AAA
• 5 Using Firewalls
• 6 Putting in Place an Intrusion Prevention System (IPS)
• 7 Securing a Local Network
• 8 Cryptography
• 9 IPsec VPNs
• 10 Studying Advanced Firewalls
• References
• Index
• End User License Agreement