Computer networks have long become the backbone of enterprise information system. The substantial share of the security problems are still encountered in enterprise network. Cyber espionage can affect ethical, military, political and economic interest anywhere. To provide secure computer networks, it is necessary to measure the relative effectiveness of security solution in the network. A network security metric enable a direct measurement and comparison of the amounts of security provided by different security solutions. In this paper, the authors propose a novel security metric zero day vulnerability prevention framework consists of bunches of algorithms.