Computer and Information Security Handbook, 2nd Edition

Chapter 29

Firewalls

Errin W. Fulp Dr. ,    Wake Forest University

Note: This chapter is available in its entirety online at store.elsevier.com/product.jsp?isbn=9780123943972 (click the Resources tab at the bottom of the page). It is also available in print in Managing Information Security.

1 Abstract

The purpose of the firewall and its location is to have network connections traverse the firewall, which can then stop any unauthorized packets. A simple firewall will filter packets based on IP addresses and ports. A useful analogy is filtering your postal mail based only on the information on the envelope. You typically accept any letter addressed to you and return any letter addressed to someone else. This act of filtering is essentially the same ...