What is an access control list (ACL)?

An access control list (ACL) is fundamentally a list of permissions that is associated with a particular resource, such as files, directories, or network devices. This list explicitly defines which users or system processes have access to that resource and what actions they are permitted to perform, such as read, write, or execute. This fine-grained control over access allows for enhanced security, ensuring that only authorized individuals can interact with sensitive data or resources, thereby helping organizations maintain confidentiality and integrity.

In the context of network security, ACLs are often utilized in firewalls and routers to regulate traffic, specifying which packets are allowed to enter or exit a network based on predefined criteria. By defining permissions in this manner, ACLs serve as a critical component in access management and security protocols, enabling organizations to enforce their security policies effectively.