The Software Design Of Embedded Linux ADSL Gateway

ADSL is a practical Broad Band technology coming up recently. With the communication age coming, it is becoming a necessary trend to provide digital multimedia communication service including voice, image, picture and text from end to end for consumers. ATM divides physical channel into several virtual channels for consumers according to different services and distributes web resources by consumers' request, which ensures the service quality and becomes the main technology in Internet.Gradually developed Embedded System is a popular technology gone with User Oriented and Application Oriented. Embedded computer is widely used in the fields including Fabricate Industry , Communication Field -. Instrument and Consumption production etc. Linux provides the basic kernel needed by embedded function and offers all user interface so becomes the embedded operating system's first choice for its opening kernel and good network support.Intelligent home network is another high-tech product brought by communication times. Using the current network technology, it makes electrical machines and other information equipment connected with each other, thus builds up a small office home office network, called SOHO. The information inside the SOHO can be changed with the information outside the SOHO through the SOHO network. However bandwidth and IP address become more serious following with the increasing of the amount of people using internet. Our main research is concerning how to use the most economical method to solve the problem to offer people with abundant, diversiform, convenient, safe, high-efficient ways to use internet.In this article, we gave a detailed project of an embedded ADSL gateway based on Linux to share the internet bandwidth, in which we used ADSL as the broadband accessing equipment and on the other end we used LAN as the networkmodel. We gave the software design of this gateway, at the same time we detailedlyHIdesigned and discussed the part of Linux kernel configuration and the kernel configuration of the gateway .The software design part mainly includes the security design and security rules management > user configuration design and user managements the design of gateway log and network service supportments. The realization of security mechanism utilized IP masquerade mechanism of Linux. In order to pass information between application lay and kernel layer conveniently, we also gave the detailed interface supportment.There are six chapters in this article, which mainly includes: the brief introduction of ADSL and ATM technology, the construction of Embedded Linux sy stem > the software design and the kernel module design of the gateway etc. At the end of this article, we summarized this paper and gave the direction on deeping into research.The Embedded ADSL gateway not only solves the problem of multi-user using internet and IP address scarcity, but also improves the speed to surf internet, and can also solve the problem of security inside SOHO network. The combination of user management and security management controls different user's requirements The administrators can know about the status of the network well and know the system trouble in good time by supporting gateway log. This gateway can be widely used in accessing of small office and small home along with the advantage of flexible ways to organize network. Consumers just need to add one ADSL SOHO gateway and no more need on altering network form. The ADSL SOHO gateway not only has the ADSL modem function but also has the function of application gateway. It not just completes the work that analog signals coming from ADSL lines are modulated and demodulated, but also shares the information. This technology would be widely used.