Описание тега whitelist
A whitelist is a list of entities that have been authorized for some access or action.
A whitelist is a list of entities that are being authorized for some access or action (entities not in the whitelist are not authorized).
Whitelists are used for software (authorized to run or not), E-mail senders, file types (authorized to upload, etc), IP addresses (authorized to connect), network ports (opened) and the like.
Whitelist is more secure but also more restricted approach than blacklist that only lists banned entities, authorizing all others.