Access Control List Overview - Cisco Catalyst 2960 series Configuration Manual

Access Control List Overview

Access lists filter network traffic by controlling the forwarding or blocking of routed packets at the interface
of a device. A device examines each packet to determine whether to forward or drop that packet, based on
the criteria specified in access lists.
The criteria that can be specified in an access list include the source address of the traffic, the destination
address of the traffic, and the upper-layer protocol.
Some users might successfully evade basic access lists because these lists require no authentication.
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Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and
feature information, see Bug Search Tool and the release notes for your platform and software release. To
find information about the features documented in this module, and to see a list of the releases in which each
feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not
required.
Information About Access Control Lists
Definition of an Access List
An access list is a sequential list consisting of at least one permit statement and possibly one or more deny
statements. In the case of IP access lists, the statements can apply to IP addresses, upper-layer IP protocols,
or other fields in IP packets. The access list is identified and referenced by a name or a number. Access list
acts as a packet filter, filtering packets based on the criteria defined in the access list.
Finding Feature Information, page 1161
Information About Access Control Lists, page 1161
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