Whitelist

A whitelist is a computer security tool used to distinguish safe data and activities from potentially dangerous ones. It is specifically used to identify which users, content, and application processes are trusted and allowed to run on a certain system.

A whitelist functions by allowing only those items specifically listed, often through a variety of filters. It is the opposite of a blacklist, where only items which are specifically listed are blocked. Whitelists are used in a variety of security contexts, including email, web and network security.

When an application is whitelisted, it means that it was specifically selected as a trusted application. This selection process is usually done by a system administrator or someone with similar security responsibilities. Additionally, whitelists can contain other kinds of entries, such as domains, IP addresses, URLs, and even entire networks.

Whitelists can be used to ensure that only certain types of content and data are allowed to enter a system, or that malicious activities are not permitted. For example, an email whitelist might allow only emails from an organization’s own domain to enter while blocking external emails from being sent or received. Similarly, a network whitelist might block external access to sensitive databases and prevent programs which could cause damage to the system from running.

Whitelists are also widely used in combination with other security measures to increase the level of security on the system. When used properly, they help to protect a system from malicious actors and software, as well as protect users from malicious websites. By requiring trusted activities and data sources, they can also help ensure that data is not leaked or used in malicious ways.