Anti-passback vs Anti-tailgating

Introduction

In physical access control (PAC), there are two terms that are similar and often misunderstood: anti-passback and anti-tailgating. This post aims to clear the misunderstanding with explanations and examples.

Anti-passback

This term refers to the PAC system's ability to track the locations of all credential holders and deny access when credentials are used at locations that are inconsistent with their holders' past access records.

The term's word choice "passback" was due to the original need for preventing illegitimate access grants enabled by the act of physically passing back access card by the person in front to the person following.

See the following examples for real life scenarios.

Example #1:

1. John presents his access card at the main entrance's access reader.

2. John enters office but accidentally drops his access card.

3. Sam picks up the dropped card and presents it to the same reader.

4. The PAC system denies access.

What happened? The system denies access because the credential owner is supposedly inside the office.

Example #2:

1. Mary enters the office in the morning by following her co-worker.

2. At lunch time, Mary presents her access card for egress at the main entrance.

3. The PAC system denies access.

What happened? The system denies access because the credential owner is supposedly outside the office.

In order for anti-passback to function, all ingress and egress must be controlled by credentials. Also, when an anti-passback violation is detected, many PAC system allows flexibility such as quotas for violations per day or enforcement on specific access points.

Anti-tailgating

This term refers to the PAC system's ability to ensure only one person shall pass an acess point for each acces grant. The following examples covers three categories of measures: physical, system, and operation.

Example #1 (physical):

• Full height revolving turnstile with metal comb feature

• Mantrap vestibule with weight sensor

Example #2 (system):

• Turnstile with optical sensors to detect tailgating

• Overhead optical sensors to detect the number of heat source nearby

Example #3 (operation):

• Security staff at access point to ensure only one person passes per credential check

• Interlocked room* equipped with video surveillance that requires security staff confirmation before allowing ingress or egress

*interlocked room means an enclosed area with more than one access controlled point, and only one access point is allowed to be open at any given time.

Summary

Both anti-passback and anti-tailgating are useful concept to enhance security. A competent security professional would help the business to striking a balance between security and convenience by facilitating collaboration amongst relevant stakeholders.