Canary

A canary in the field of information security is a hardware or software solution that is deployed as a decoy within the network. Upon access of a canary, an alert or event will be sent to a predefined location like an email address or application.

The name canary refers to the caged canaries that were in coal mines. Miners would take them with them as an early warning signal against dangerous gases like carbon monoxide. If the canary suddenly died, the miners would know about the presence of the gas and exit the tunnels.