IPv4 Access Control Lists (ACLs)

Overview

Overview

Types of IPv4 ACLs

A permit or deny policy for IPv4 traffic you want to filter can be based on source address alone, or on source address plus other factors.

Standard ACL: Use a standard ACL when you need to permit or deny IPv4 traffic based on source address only. Standard ACLs are also useful when you need to quickly control a performance problem by limiting IPv4 traffic from a subnet, group of devices, or a single device. (This can block all IPv4 traffic from the configured source, but does not hamper IPv4 traffic from other sources within the network.) A standard ACL uses an alphanumeric ID string or a numeric ID of 1 through 99. You can specify a single host, a finite group of hosts, or any host.

Extended ACL: Use an extended ACL when simple IPv4 source address restrictions do not provide the sufficient traffic selection criteria needed on an interface. Extended ACLs allow use of the following criteria:

source and destination IPv4 address combinations

IP protocol options

Extended, named ACLs also offer an option to permit or deny IPv4 connec­ tions using TCP for applications such as Telnet, http, ftp, and others.

ACL Applications

ACL filtering is applied to IPv4 traffic as follows:

Static port ACL: any inbound IPv4 traffic on that port.

Dynamic port ACL: on a port having an ACL assigned by a RADIUS server to filter an authenticated client’s traffic, filters inbound IPv4 traffic from that client

(For information on RADIUS-assigned ACLs, refer to chapter 6 “Configuring RADIUS Server Support for Switch Services”.)

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