Abstract: NSAS (Network Situation Awareness System) can identify and predict potential attacks. It plays an important role in improving the emergency response capacity and proactive defense capability of the networks. Existing NSASs have many faults, such as lacking for multi source information, higher computational complexity, which arc difficult to be applied to larg}scale networks and real-time situational awareness. This paper introduced an NSAS for largescale network. The situational awareness model was proposed first, and then the details of key technologies, including data fusion, correlation analysis, index quantification and event predication,were given. I}he experimental results demonstrate the effectiveness and reasonability of the proposed model.

Key words: Network security, Index, Index system, Situation awareness