Based On Wince Mobile Terminal Firewall System Design And Realization

With the fast development and growing popularization of wireless devices such as laptop, smart phone and PDA, corresponding hardware and software are also developing rapidly. At the same time, network attack aimed at wireless devices such as mobile terminals is also increasing rapidly. Microsoft Windows CE is an embedded OS which has morn function. It supplies a lot of services based on network, e.g. Internet,remote control protocol and VoIP. It is also one of the Operating Systems which are chosen by current smart phone. But Windows CE does not have any security schemes, so doing research on mobile terminal security protection technology based on Windows CE is very useful.At present, personal firewall based on Windows platform which is installed on personal computer is relatively mature. But under the environment of future wireless network or mobile computing, the safety boundary of wired network disappears gradually, it's necessary for us to research some useful mobile terminal firewall technologies and practical scheme. Researches on mobile terminal security protection technology only concern with caller number filtering, short message filtering and virus prevention, while studies on the firewall software which is able to effectively control the behavior of Internet use for mobile terminal has just started.After analysing the function requirement and implementation technology of personal firewall system based on Windows platform which is installed on personal computer, this dissertation studies several key technologies, e.g. the general structure of Windows CE, the implementation of communication network module and network data-packets interception. Finally, a new technology is proposed which the kernel mode NDIS HOOK and user mode SPI HOOK get together, the research idea of network packet filteris realized. The main works are as follows:1. According to the basic principle of firewall, while fully considering the mobile terminal's limit and restraint to resources as well as users' characteristic, we have analysed the need of the system detailedly, determined data structure, functional requirements, performance requirements, user interface requirements and development environment and tools.2. According to system requirements, we have designed the overall frame and the modular structure of the mobile terminal firewall system, formulated system's first-level flowchart and the second-level flowchart, and made the description of the detailed functions of each module.3. We have defined the data structure of access rule file, log file, and each filtering module. While we have explained the meaning and usage of each variable.4. We have designed each interface module, including communication module, dominating function module, shared variable module and general appended function and so on. We have also specifically explained the function of each module, parameter type and the type of return value.5. We have designed the system's testing scheme. The result of functional test and performance test has also been presented. It proved that the system has achived design objectives.