The ABCs of ACLs: A Beginner's Guide to Access Control

The ABCs of ACLs: A Beginner's Guide to Access Control was initially published on Tuesday January 17 2023 on the Tech Dev Blog. For the latest up-to-date content, fresh out of the oven, visit https://techdevblog.io and subscribe to our newsletter!

Welcome to the world of ACLs! ACLs, or Access Control Lists, are a fundamental concept in computer security. They allow administrators to control who has access to specific resources (such as files or network segments), and what actions they can perform on those resources. In this article, we introduce the concept of ACLs and explain the most important concepts and best practices associated with them. Read on, and you'll be an ACL pro in no time!

What is an ACL?

An ACL is a set of rules that define who has access to a particular resource and what actions they can perform on that resource. These rules are usually based on the user's identity, such as their username or group membership, and can be used to control access to both local resources, such as files and directories, and remote resources, such as network segments or cloud services.

ACLs are implemented in a variety of ways, depending on the operating system or network device in use. In most cases, they are implemented as a list of rules, with each rule specifying a user or group and the permissions they have for a specific resource.

Basic concepts of ACLs

Resources: Resource refers to any item, object or data that requires access to be controlled. These resources can be physical or digital, such as a file, folder, network segment, cloud service, printer, or database.
Permissions: The permissions associated with a resource determine what actions a user can perform on that resource. Common permissions include read, write, and execute.
Users and groups: ACLs are usually based on the identity of the user or group requesting access to a resource. Users and groups are typically defined in the operating system or network device.
Deny and allow: ACLs can include both deny and allow rules. Deny rules take precedence over allow rules. So if a user is denied access to a resource, they will not be able to access it. Even if they are included in an allow rule.

Acronyms

ACE: Access Control Entry, represents a rule in an ACL.
NACL: Network Access Control List, an ACL that controls access to network resources.
DACL: Discretionary Access Control List, an ACL that controls access to local resources.
SACL: System Access Control List, an ACL that controls access to system resources.

Best practices for using ACLs

1.Keep it simple: When creating ACLs, it's important to keep the rules as simple as possible. Complex rules can be difficult to understand and can lead to errors.

2.Use deny rules sparingly: Deny rules should be used sparingly, as they can make it difficult to understand who has access to a resource.

3.Regularly review and update: ACLs should be reviewed and updated regularly to ensure that they are still appropriate for the current environment.

4.Test: It's important to test the ACLs to ensure that they are functioning as expected.

Conclusion

In summary, an ACL is a set of rules that define who has access to a particular resource and what actions they can perform on that resource. It's important to keep the rules simple, use deny rules sparingly, regularly review and update and test them.

ACLs are an essential tool for managing access to resources and ensuring the security of your systems. By understanding the concepts and best practices associated with ACLs, you can create effective and secure access control systems.

And there you have it! Your first introduction to ACLs! You are now well on your way to becoming an ACL pro...