Piggybacking

Piggybacking is a term used across domains to describe gaining access to a resource or benefit by riding on someone else’s existing access or activity. The concept is applied in physical security, information technology, and transportation, among other contexts.

In physical security, piggybacking (also called tailgating) occurs when an individual gains entry to a restricted area by following someone with legitimate access. Common situations include an unauthorized person slipping behind an employee through a door or turnstile. Preventive measures include strict access control systems, turnstiles or mantraps, authentication requirements, and security awareness training. Policies generally discourage assisted entry and require verification of each person’s credentials.

In information technology, piggybacking describes unauthorized use of another user’s network connection or session. This can involve connecting to an unsecured or weakly secured wireless network or exploiting a valid session to access resources. Preventive measures emphasize strong encryption (such as WPA3 for wireless networks), robust authentication, network segmentation, regular monitoring, and clear usage policies. Legitimate forms of piggybacking can occur when users knowingly share connectivity or services within authorized boundaries, such as tethering or shared access with consent.

In transportation, piggybacking refers to intermodal transport where trucking trailers or containers are carried on railcars or barges. This approach, often known as trailer-on-flatcar or intermodal shipping, can improve efficiency and reduce highway congestion by combining road flexibility with rail capacity.

In computing, piggybacking can describe delaying an acknowledgment until data can be sent in the same packet. This optimization improves efficiency but can introduce latency or synchronization challenges.

Overall, piggybacking raises security, privacy, and efficiency considerations that require appropriate controls and clear policies.