Research And Implementation On Personal Firewall System

Firewall is playing an important role in the network. However, personal firewall which is traditional and has simple function isn't able to satisfy by the development of the user's security consciousness and network attack means. Firstly, the function requirement of the personal firewall is expanded; firewall is needed to provide protection in different layers. Secondly, the efficiency and performance requirement of the personal firewall is also increased. The efficiency problem becomes very prominent when the function is improved. Personal firewall doesn't only keep excellent efficiency and low resource use but also has security functions in different layer on the base of security protection in practice. Based on the Windows drivers and Winsock2, using rule table and strategy table to filter network data packets, manage local file system and local process information and thread information,personal firewall offers more secure and effective services in kernel model and user model. On the basis of further research of firewall technology, analysis of the model of system and analysis of the system dataflow, five bottlenecks were ascertained: low efficiency in filter rule table, frequent interaction between driver tier and intermediate service tier, frequently data exchanging between processes, low efficiency in reading and writing files, low efficiency in search in the program explore strategy table. Seven methods were proposed to improve the system efficiency and performance: rule table optimize, divide rule table, communicate by share buffer and event, memory mapping, compute in driver, dimidiate search, and use index table. By analyzing and improving the firewall's efficiency and performance above, a personal firewall which is based on Windows operation system is designed and founded. The personal firewall which makes use of the strategy mentioned above obtains the good effect of protection.