Construction and Application of Network Security Defense Model

To assure network security, the paper constructs a kind of reasonable security defense model based on analyzing security character for physical layer, network layer, system layer, application layer, and management layer of network. Supporting by router, Ethernet switch, firewall, network management, and operational platform, the model is a perfect defense system which composed by aspects of security authentication, access control, filter examination, scan, detection, VPN, audit analysis, policy service. Last, combining E-government application, a practical example is presented to improve security performance of network.