“互联网+”的到来促进了应用软件在多个领域得到广泛普及和使用,提高了人们工作、生活和学习的共享化、智能化、自动化水平。“互联网+”在为人们带来便利的同时也潜藏着风险,黑客、木马和病毒可以隐藏在正常文件中盗取人们的隐私、机密信息,损害了人们的人身、经济权益。本文构建了一个基于主动模式的网络安全防御系统,引入了深度包过滤、入侵检测、状态检测等技术,提高网络安全防御性能。 The arrival of “Internet + ” has promoted the popularization and use of application software in many fields and improved the sharing, intelligence and automation of work, living and learning. “Internet + ” also brings risks to people’s convenience. Hackers, Trojans and viruses can hide in the normal files to steal people’s privacy and confidential information and harm people’s personal and economic rights. This paper constructs a network security defense system based on active mode, introduces technologies such as deep packet filtering, intrusion detection and state detection to improve the network security defense performance.