Protocol-based intrusion detection system

A protocol-based intrusion detection system (PIDS) is an intrusion detection system which is typically installed on a web server, and is used in the monitoring and analysis of the protocol in use by the computing system. A PIDS will monitor the dynamic behavior and state of the protocol and will typically consist of a system or agent that would typically sit at the front end of a server, monitoring and analyzing the communication between a connected device and the system it is protecting.

Source: Wikipedia — Protocol-based intrusion detection system (CC BY-SA 4.0)