What does the term 'Whitelist' indicate in the context of ACLs?

In the context of Access Control Lists (ACLs), the term 'whitelist' typically means to allow traffic that is specifically identified as safe or trusted while blocking all other traffic. This practice enables stricter network control by permitting only a defined set of sources, destinations, or services while denying anything else that does not meet these criteria.

In a whitelisting approach, only those entries that are explicitly allowed in the list can access the resources, while all other traffic is automatically denied. This is particularly useful for enhancing security in a network environment because it reduces the attack surface by preventing any connections that are not prescreened and approved.

By defining an explicit list of allowed network traffic, organizations can implement fine-grained security measures, ensuring that only the most trusted sources can interact with their network resources. The use of whitelists is common in environments where security is a paramount concern, allowing for tighter control over what can access network segments and applications.