Technical security metrics provide measurements in ensuring the effectiveness of technical security controls or technology devices/objects that are used in protecting the information systems. However, lack of understanding and method to develop the technical security metrics may lead to unachievable security control objectives and incompetence of the implementation. This paper proposes a model of technical security metric to measure the effectiveness of network security management. The measurement is based on the effectiveness of security performance for (1) network security controls such as firewall, Intrusion Detection Prevention System (IDPS), switch, wireless access point, wireless controllers and network architecture; and (2) network services such as Hypertext Transfer Protocol Secure (HTTPS) and virtual private network (VPN). We use the Goal-Question-Metric (GQM) paradigm [1] which links the measurement goals to measurement questions and produce the metrics that can easily be interpreted in compliance with the requirements. The outcome of this research method is the introduction of network security management metric as an attribute to the Technical Security Metric (TSM) model. Apparently, the proposed TSM model may provide guidance for organizations in complying with effective measurement requirements of ISO/IEC 27001 Information Security Management System (ISMS) standard. The proposed model will provide a comprehensive measurement and guidance to support the use of ISO/IEC 27004 ISMS Measurement template.