Billing Security Gateway System Linux Part Of The Design And Realization

Reasonable and effective network accounting is a guarantee of normal running and popularization of network. As one part of network operation and management, network accounting is very important.The system of this paper founds mainly based on Linux platform. Through the thorough analysis of the Netfilter framework principle of Linux Kernel 2. 4, also having used its powerful property, we design and implement a kind of Secure Gateway System with Accounting based on users.In the process of system design, All functions are coded with modularization, All modules are integrated into system after strict test. The functions that have implemented include user verification collection and accounting of data flow , access control based on users, network address translation, packet filtering and log record.In order to solving the problem of performance bottleneck on gateway, we adopt various advanced and ripen technologies, such as core code performing in kernel space, responding the concurrent access in minimum time with multi-process or multi-thread programming and fast queue mechanism, fast locating users with Hash algorithm, fast differentiating flow type with binary-search algorithm and high-speed cache etc.From the result of test and application, it proves that the system operates stable, accounting for flow is accurate and well real-timed, access control and security mechanism for packet filtering is well operated, also it is convenient for user administration.Above all, it is a system with high practical value.