What Does 'ACL (Access Control List)' Mean?

An access control list (ACL) is a list of permissions that are associated with a particular resource, such as a file, folder, or network device. The ACL specifies which users or groups are allowed to access the resource and what actions they are allowed to perform on it.

ACLs are used to implement access control in computer systems and networks and are a key component of security and privacy protocols. They help to ensure that only authorized users can access sensitive information and that they can only perform certain actions on that information.

There are two main types of ACLs: discretionary and mandatory. A discretionary ACL (DACL) is a list of permissions that is associated with a resource and that can be modified by the owner of the resource. A mandatory ACL (MACL) is a list of permissions that is associated with a resource and that cannot be modified by the owner of the resource.

ACLs can be implemented in a variety of ways, including through software applications and operating systems, network protocols, and hardware devices. For example, an ACL might be implemented through a file system on a computer, through a firewall on a network, or through a security device such as a router or switch.

In a file system, an ACL might specify that a particular user is allowed to read and write to a file, while another user is only allowed to read the file. In a network, an ACL might specify which traffic is allowed to pass through a firewall and which traffic is blocked.

ACLs are typically used in conjunction with other security measures, such as authentication and encryption, to provide a comprehensive security solution. They are an important tool for protecting against unauthorized access to sensitive information and ensuring the privacy and integrity of data.

More information

In many operating systems, including Mac OS X, ACLs can be managed through a graphical user interface (GUI). This allows users to easily view and modify the permissions associated with a particular resource, such as a file or folder.

To modify ACLs using a GUI, users typically need to have the appropriate permissions. For example, in Mac OS X, a user must have administrative privileges to modify the ACLs of certain system files and folders.

ACLs can also be modified using command-line tools and scripts. This can be useful for automating tasks, such as setting permissions on a large number of files or folders, or for integrating ACL management into custom applications.

It’s important to note that ACLs are just one aspect of access control. They are used to specify which users or groups are allowed to access a particular resource and what actions they are allowed to perform on it.

However, they do not provide any authentication or identification of users. In order to ensure that only authorized users can access a resource, ACLs must be used in conjunction with other security measures, such as authentication and encryption.