Shahab Forghani - Department of Computer Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran
Navid Habibi - Department of Computer Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran
Mohsen Firoozbakht - Department of Computer Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran

Undoubtedly, it is highly essential to have tools in order to evaluate the sustainability of computer networks in case of unauthorized intrusions. In this paper, a network security metric is presented which is based on attack duration. This metric initially models the attack perquisites in form of a tree according to the network configuration and in the next step, calculates the value of metric with gamma distribution. It was concluded that the calculated metric was not accurate but it could be used to compare security status of similar computer networks and also different configurations of the same network. This criterion is not enough to judge about total security of network but it covers one of the important aspects of attack, i.e. time. It is expected that this method will help researchers contrive more accurate metrics for network security.

Network security; Security Metric; Attack Duration; Time Metric;