Business Data Communications, Fourth Edition Chapter 10: Network Security

Learning Objectives Describe the security duties of a network administrator List the types of physical security used on a computer network Describe a device that can be used for physical security List three types of software security Describe two types of encryption Chapter 10: Network Security2

Learning Objectives List three encryption standards Describe digital signatures and digital certificates Define the Secure Sockets Layer List the differences between a virus and a worm Describe firewalls Chapter 10: Network Security3

Introduction Security is extremely important in today’s network environment Hackers can be a serious problem for both corporate and private computers Physical and software security are used Network administrator develops and implements security systems Chapter 10: Network Security4

Physical Security Can use a locked room for computers Remote clients not as easily locked up Today’s open environment with PCs everywhere presents a problem Handhelds and laptops connected to corporate networks are of particular concern Chapter 10: Network Security5

Physical Security Measures to Control Physical Access to Networks –Fingerprint device –Video camera –Movement detection devices –Medium Wires are more secure than wireless Fiber optic most secure of wired systems –Encryption used to encode data –Dial-in access is a problem Chapter 10: Network Security6

Physical Security Data/Network Security Equipment –Fingerprint/voiceprint devices to prevent access –Callback unit Blocks unauthorized network access Used with dial-up lines Computer calls user back at predetermined number Will not work with mobile computer that uses different phone number Chapter 10: Network Security7

Software Security IDs and Passwords –Assigned to users, must be protected –Need to use password that is not obvious –Should be changed periodically Some systems force users to change them –Network software monitors use and reports on attempted unauthorized access –Applications can require IDs as well Chapter 10: Network Security8

Software Security Encryption –Scrambling data before transmission –Uses encryption key –Plaintext versus cipher text Chapter 10: Network Security9

Software Security Encryption –Symmetric key encryption One key used by both ends of transmission Data Encryption Standard (DES) (56 bits) Triple DES – more secure (112 bits) Blowfish (32 to 448 bits) International Data Encryption Algorithm (128 bit) Clipper Chip Chapter 10: Network Security10

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Software Security Encryption –Public Key Encryption Two keys are used (public & private keys) RSA is most common form Pretty Good Privacy (shareware) –Elliptic Curve Cryptography (ECC) Uses logarithm to create key Chapter 10: Network Security12

Digital Signatures Used for verification of files transmitted over a network Impossible to counterfeit Digital Certification –E-Signature – Actual handwritten signature attached to a document Makes a document legal Chapter 10: Network Security13

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Digital Signatures Digital Certification –Digital Certificates – Verifies a persons identity using multiple forms of identification Combined with digital signature –Wireless networks use encryption, digital signatures and digital certificates to secure data Chapter 10: Network Security16

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Secure Sockets Layer (SSL) Allows security of credit card numbers for e-commerce URL starts with Software is on the server and client PC (included with most browsers now) Many sites also encrypt information before it is sent over the Internet Chapter 10: Network Security18

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Security Issues Forms of Computer Attacks –Virus –Worm Internet Worm – 1988 –Antivirus software needed, with updates –Denial of Service (DoS) attacks Chapter 10: Network Security20

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Security Issues Firewalls –Software program –Determines if user/software can access a system –Used in corporate networks and home computers –Trojan Horse – hidden program that executes by a trigger Chapter 10: Network Security22

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Security Issues Firewalls –Packet-level firewall Determines if packets should pass to the network IP Spoofing – intruder appears to be from a valid address on the network –Application-level firewall Prevents unauthorized access to applications –Proxy Server Creates artificial addresses so to the outside, it looks like only one server exists on the corporate network, rather than several Chapter 10: Network Security25

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Summary Network security is high priority issue Physical security is one level of defense Software security is used extensively –Several types of encryption are used Digital signatures and digital certificates are used to verify a user’s identity Chapter 10: Network Security28

Summary Viruses and worms are a threat Denial of service attacks have become a problem Firewalls protect a network from outside access Chapter 10: Network Security29

Chapter 10 Complete