Chapter 6. Access List Introduction

Cisco access control lists (ACLs), pronounced ackuls, are one of the most powerful features of the Cisco IOS. This chapter is an introduction to ACLs. It covers basic guidelines when dealing with ACLs, including tips, recommendations, considerations, and cautions.

This chapter is divided into three basic sections:

• Access list overview

• Basic ACL configuration

• Wildcard masks

Each section contains many examples to illustrate the use of ACLs and their components.

This chapter covers only the basic configuration of ACLs; subsequent chapters in this book cover the operation and configuration of the different types of ACLs that the Cisco IOS supports, as well as the use of ACLs to secure a perimeter router.