Access Control Lists (ACLs) on Cisco Routers

Name: Access Control Lists (ACLs) on Cisco Routers
Rating: 4.7 (124 reviews)

Understand, Configure, and Troubleshoot ACLs on Cisco Devices

Created byEd Harmoush

Last updated 6/2021

English

English [Auto],

What you'll learn

Configuring and Troubleshooting access lists on Cisco devices

Course content

1 section • 8 lectures • 1h 15m total length

What are Access Control Lists?8:22
Identify traffic with access control lists and apply them to an interface, distinguishing standard ACLs that use source IP from extended ACLs that also filter destination IP, ports, and protocol.
Numbered ACL Syntax8:48
Learn the syntax of numbered ACLs on Cisco routers, covering standard and extended lists, aces, permit/deny actions, and ip/tcp/udp/icmp matching.
Numbered ACL Configuration Demonstration14:23
Demonstrate configuring a numbered extended ACL on Cisco routers, matching IP, ICMP, and TCP traffic with specific sources, destinations, and ports. Explain first-match processing and the implicit deny.
Named ACL Syntax and Features4:59
Explore the named ACL syntax and features on Cisco routers, compare them with numbered ACLs, and learn how standard or extended types, ID names or numbers, and sequence control work.
Named ACL Configuration Demonstration13:27
Learn to configure named access-lists on Cisco routers, converting from numbered ACLs, managing sequence numbers, inserting and deleting entries, and resequencing for flexible control.
IPv6 ACLs11:33
Explore configuring IPv6 access control lists on a Cisco router using named IPv6 ACLs, including syntax differences, extended IPv6 ACLs, and crafting entries for specific hosts, subnets, and ports.
Applying ACLs to Interfaces3:42
Apply access control lists to interfaces on Cisco routers, since ACLs take effect only when applied, using ip access-group for ipv4 and ipv6 traffic filter with in or out direction.
ACL Placement: Closer to Source or Destination?10:11
Place standard access lists closest to the destination to avoid blocking unintended traffic; apply extended lists closest to the source for granular, early traffic dropping.

Requirements

Basic familiarity with Cisco IOS

Description

Access Control Lists, or ACLs, are a tool that is used to define traffic on Cisco routers.

By themselves, they merely identify a particular set of traffic. How you apply the ACL then determines what occurs to that traffic.

For instance, if you apply an ACL to…

… an interface? Matched traffic is allowed through
… a Crypto map? Matched traffic is secured and sent through a VPN
… a NAT configuration? Matched traffic is translated
… a NAT Exemption configuration? Matched traffic is not translated
… a Route Map? Matched routing advertisement are accepted
… a QoS Classification? Matched traffic is prioritized (or de-prioritized)

The core of doing any of these successfully is understanding how to configure access lists on Cisco routers. And that is what this video series will teach you.

Of all the ways to apply an ACL listed above, the most common is to applying and ACL to an Interface. The purpose of such an ACL is to filter the “bad packets” from the “good packets”. In fact, when you apply an ACL to an interface, it is sometimes referred to as a Packet Filter.

To that end, Packet Filter ACLs are the focus of this video series. But, watching this video series will teach you how to configure ACLs for any other application listed above.

Who this course is for:

CCNA students
Network Engineers / Admins