Abstract: NSSAS(Network Security Situation Awareness System) can perceive the overall network security situation.It plays an important role in improving the emergency response capacity and active defense capability of the networks.Existing NSSAS is limited in processing capacity,which is difficult to apply to the national backbone network and other larg-scale networks. This paper introduced a NSSAS designed for larg}scale networks named YHSSAS. The situational awareness model was proposed first, and then several key technologies, including data integration, correlation analysis,indicators quantification and event predication,were detailed.

Key words: YHSSAS, NSSAS, Data integration, Correlation analysis, Index system, Event predication