Computer Security Handbook, Fifth Edition

CHAPTER 31

WEB MONITORING AND CONTENT FILTERING

Steven Lovaas

31.1 INTRODUCTION

31.2 SOME TERMINOLOGY

31.3 MOTIVATION

31.3.1 Prevention of Dissent

31.3.2 Protection of Children

31.3.3 Supporting Organizational Human Resources Policy

31.3.4 Enforcement of Laws

31.4 GENERAL TECHNIQUES

31.4.1 Matching the Request

31.4.2 Matching the Host

31.4.3 Matching the Domain

31.4.4 Matching the Content

31.5 IMPLEMENTATION

31.5.1 Manual “Bad URL” Lists

31.5.2 Third-Party Block Lists

31.6 ENFORCEMENT

31.6.1 Proxies

31.6.2 Firewalls

31.6.3 Parental Tools

31.7 VULNERABILITIES

31.7.1 Spoofing

31.7.2 Tunneling

31.7.3 Encryption

31.7.4 Anonymity

31.7.5 Translation Sites

31.7.6 Caching Services

31.8 THE FUTURE

31.9 SUMMARY

31.10 FURTHER READING

31.11 NOTES

31.1 INTRODUCTION.

The Internet has been called a cesspool, sometimes in reference to the number of virus-infected and hacker-controlled machines, but more often in reference to the amount of objectionable content available at a click of the mouse. This chapter deals with efforts to monitor and control access to some of this content. Applications that perform this kind of activity are controversial: Privacy and free-speech advocates regularly refer to “censorware,” while the writers of such software tend to use the term “content filtering.” This chapter uses “content filtering,” without meaning to take a side in the argument by so doing. For more on the policy and legal issues surrounding Web monitoring and content filtering, see Chapters 48 and ...