A mantrap is a physical security system designed to control access to a secure area through a small space that can only fit one person at a time. This space typically has two sets of interlocking doors. The first set of doors must close before the second set opens, preventing tailgating or piggybacking, where an unauthorized person follows an authorized person into a restricted area. Mantraps can be equipped with biometric verification systems to ensure that the person in the mantrap is authorized to enter the secure area.

References: The concept of a mantrap as a security measure aligns with the Certified Network Defender (CND) objectives which include understanding and implementing physical security controls for network security. The use of mantraps is a recognized method to prevent unauthorized access and is mentioned in various security frameworks and guidelines as an effective physical security measure123.