What security feature allows only one person inside and requests their identity?

A mantrap is a physical security feature designed to control access to secure areas by allowing only one person to enter at a time while verifying their identity. It typically consists of two sets of doors with a small space in between. When someone enters the first door, it closes, creating a secure environment before they can be granted access to the second door, which leads into a more secure area. This ensures that unauthorized individuals cannot follow someone in, enhancing security.

The use of a mantrap is effective in environments where high security is required because it can also include identification systems such as card readers or biometric scanners to ensure that the person trying to gain access has the proper permissions. Thus, the primary function of a mantrap is to manage and control individual access to sensitive areas, which aligns perfectly with the requirement of allowing only one person inside while confirming their identity.