Department of Computer Science and Engineering Department of Electronic, Electrical and Computer Engineering Huawei Huawei Fraunhofer Institute for Secure Information Technology This document describes an information model and the corresponding YANG data model for monitoring Network Security Functions (NSFs) in the Interface to Network Security Functions (I2NSF) framework. If the monitoring of NSFs is performed in a comprehensive way, it is possible to detect malicious activity, anomalous behavior, and the potential sign of denial of service attacks in a timely manner. This monitoring functionality is based on the monitoring information that is generated by NSFs. Thus, this document describes not only an information model for monitoring NSFs along with a YANG data diagram, but also the corresponding YANG data model for monitoring NSFs.