What Is Access Control List (ACL) in Networking? Explained with Examples

What Is Access Control List (ACL) in Networking? Explained with Examples

In today's fast-changing world of cybersecurity, network control and traffic filtering are critically important for ensuring system integrity. Perhaps the most important tool employed to protect networks is the Access Control List (ACL). If you're an aspiring ethical hacker, network engineer, or seeking certifications such as CEH (Certified Ethical Hacker), you can't afford to ignore ACLs.

In this blog post, we’ll cover:

What is Access Control List (ACL)?

Types of ACL in networking

Real-world examples of ACL use

Difference between ACL and Banner MOTD

Relevance in online ethical hacking training and certification

What Is Access Control List (ACL) in Networking?

An Access Control List (ACL) is a collection of rules that is employed to regulate network traffic and restrict access to network resources or devices. ACLs are applied on switches, firewalls, and routers to allow or block traffic depending on conditions like IP address, protocol type, or port number.

Main Functions of ACLs:

Block or filter traffic based on destination/origin IP addresses

Restrict access to a certain service or devices

Improve network performance by cutting unnecessary traffic

Implement security policies

Networking Types of ACL

There are two popular types of ACLs used in Cisco networks:

1. Standard ACL

Filters traffic based only on source IP address

Less complex but not very flexible

Applied near the destination

Network Use Cases of ACL

Access Control Lists are highly essential for enterprise-level network security. Here are some real-world situations where ACLs are implemented:

Limiting Internet Access

Restrict web access for specific IPs during working hours.

Access Control to Servers

Restrict communication of only particular devices with important database servers.

Network Performance Enhancement

Stop unwanted traffic to decrease the load on particular segments.

Firewall Configurations

ACLs form the backbone of most firewall rule sets.

VLAN Access Control

Stop inter-VLAN communication in some configurations.

ACL List: Basic Configuration Checklist

To set up an ACL, refer to the following steps:

Determine the traffic to be controlled

Select standard or extended ACL

Create the ACL with access-list command

Implement it to an interface with ip access-group

ACL vs. Banner MOTD: Getting to Know the Difference

While ACLs are applied to manage network traffic, the banner motd command is applied to display warning or informational messages to users when they connect to a device such as a Cisco router or switch.

Which Is the Command to Configure a Banner to Be Displayed When Connecting to a Switch?

Use the following banner motd command in configuration mode:

bash

Copy

Edit

Switch(config)# banner motd #Unauthorized access is prohibited#

What Is the Purpose of the Banner MOTD Command?

The MOTD (Message of the Day) banner is a legal notice or user policy message prior to login. It's usually employed on corporate networks for:

Security disclaimers

Announcements

Policy reminders

It does not manage traffic like an ACL network, but it is a crucial function for security awareness and compliance.

Significance of ACL in Ethical Hacking Training

Any future ethical hacker must understand ACL in networking. It is a core idea in online ethical hacking training and a critical subject in the CEH online training and certified ethical hacker training.

This is why ACL training is crucial in security and hacking training:

Identifies weaknesses in networks

Instructs on how traffic control affects attack vectors

Allows for penetration testers to bypass or test ACL implementations

Needed to configure firewalls, routers, and switches

Top Online Ethical Hacking Courses to Master ACLs and Network Security

We at UniNets provide comprehensive online ethical hacking training with real-time labs, ACL setup, and Cisco switch administration.

Recommended Courses:

Ethical Hacking Training Course (Online)

Spend quality time learning network protocols, ACLs, and Cisco command lines.

Certified Ethical Hacker Course (CEH Training Online)

emphasizes vulnerabilities, access control systems, and perimeter defenses.

Online Ethical Hacking Certification Programs

Get certified learning real-world hacking techniques and network security principles.

Elearning Ethical Hacker Track

Best for independent learners with labs, video, and interactive assessments.

Whether you are a beginner or an IT professional, our courses are designed to make you an expert ethical hacker with the ability to secure today's networks.

Conclusion

Access Control Lists (ACLs) are perhaps the most critical piece of equipment in the toolkit of any network administrator or ethical hacker. They enable experts to block traffic, protect systems, and implement policy at the network level. Joining ACLs with banner motd Cisco commands forms a secure and compliant access environment.

At UniNets, our online hacking training and ethical hacking training courses are designed to give you hands-on experience with ACLs, banners, routing, and more. Get started with a CEH online course and take your career to the next level.