Design And Implementation Of Internet Content Filtering System In The Minors

With the development of Internet technology, Internet has been the biggest resources depository in the world. While on the Internet, the good and the bad information are mixed together. Besides convenience, the arbitrary browse and release of information bring people a great negative effect. Although the current security tools, such as firewall, anti-virus software and intrusion detection system, do better in the prevention of security threats, these tools are mainly aiming at the security protection of enterprise network but not home network. This situation will cause a large number of young persons to be addicted to games, browse pornographic or violent website, and finally be guided to commit crime. So how to effectively protect young persons from harmful information and form a healthy climate of Internet use become a bounden responsibility in the current society.After analyzing the various reasons why many young persons are addicted to games, we find that the most important reason is the lack of effective and controllable management mechanism on the Internet. So the security filtering and supervision in home access to Internet are selected for researching in this dissertation. Meanwhile, several filtering technologies and methods are adopted to control the information which is released on the Internet. All the things we do will help the parents manage their children's behavior of Internet use and protect the children from different angles such as technology and supervision. The main works are as follows:1. There are many deficiencies in the current content filtering products. For example, their filtering technologies are either too simple to use or relatively advance but the price of the product is very expensive. So the spread and popularization of Internet are affected in family area. In this dissertation, an open source system named Network Nanny, which is used for filtering network content ,is implemented. It can be installed directly on home computer, and have a lot of advantages, such as easy-installing, easy-configuring and charge free. 2. The supervision to the young persons' behavior of Internet use. Several technologies of data packet interception on windows operating system are analyzed, while the filtering technologies of TCP/IP header are studied. By filtering some specific IP address ,TCP and UDP ports, the limitations to the specific URLs and service are realized. With the help of white list mechanism, young persons could only access specific green websites, and the security control and protection are realized effectively.3. The supervision to network content visited by young persons. Considering the dynamicity of websites and the uncertainty of network content, the Network Nanny realizes data packet interception on driver layer by adopting Winsock SPI on application layer. After that data packets are sent to application layer. So the system could realize multilayer filtering model from network to application layers and the filtering effect is very well. Cooperate with black list mechanism, unhealthy and violent websites can be filtered.4. After designing, debugging and programming, a system named Network Nanny is implemented on windows operating system. The performance testing results show that the system could effectively manage young persons' behavior of Internet use according to the formulated network accessing strategy and timely blockade the hurt to young persons produced by harmful information on the Internet. In a word, the initial researching objective is realized.