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Understanding the Network: A Practical Guide to Internetworking by Martin J. Michael

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Access Control Lists

Originally, access control lists (ACLs) were used for their packet-filtering capabilities, most commonly for IP security filtering. As the IOS software has evolved, the usefulness of ACLs has also grown (depending on the protocols and features supported by IOS) to allow filtering capabilities for all the IOS-supported Layer 3 protocols (and MAC addresses), and traffic TOS and QOS identity services for traffic control tools.

The ABCs of Access Control Lists

An ACL (or access-list) is a series of action statements used for examining network protocol traffic. There are two possible action statements:

  • permit

  • deny

ACLs perform different tasks, depending on how they are applied. After the list is applied, the router's network ...

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