What is the function of Access Control Lists (ACLs) in networking?

Access Control Lists (ACLs) play a critical role in networking by filtering traffic based on specified rules. This allows network administrators to define precisely which types of traffic are permitted or denied to pass through a network interface. By setting up an ACL, you can control access to resources based on various criteria, such as IP addresses, protocols, or ports. For example, an ACL can be configured to allow web traffic (HTTP) from certain IP addresses while denying all other traffic, providing a way to enhance security and ensure that only authorized users can access certain resources.

Using ACLs effectively helps to manage and protect network resources, prevent unauthorized access, and mitigate potential security threats. This function is crucial in both enterprise networks and the management of network devices. ACLs do not intrinsically enhance network speed, encrypt data, or provide physical security; instead, their primary role revolves around establishing rules that dictate how data packets are handled as they traverse the network.