| Embedded Internet is a technology that the devices access with Internet by embedded module but not PC and exchange the information by the Internet. In the recent years, it is one of the study hotspots in the area of industrial automatization, which applies the embedded Internet technology in the area of industrial automatization and realizing the intelligent and remote monitor system. According to the deficiencies, such as, the large size, the high cost, the low security and the week function that exist in the conventional embedded Internet, this paper puts forward the connecting means of embedded Internet which is based on the embedded and secure Web gateway.The study goal of this paper is to design and implement the embedded and secure gateway system based on field bus. As the hinge where the field bus and Internet exchange the data, it is not only a transmitter but also possessing the capability of security and the functions of various networks service, such as, WWW, FTP and e-mail etc. It is provided with some intelligence and compatibility.Firstly, this paper introduces the developing history, actuality and the trend of embedded Internet technology. Then it analyzes and compares the domestic and foreign development of embedded Internet technology, and concludes the mainly problems that exist in the embedded Internet when it is used in the area of industrial control. Further more, it probes into the developing and applying trend of embedded and secure Web gateway based on CAN bus, form the aspects of low cost, small size, high performance, high security, multifunction and high efficiency.In the system design of the gateway system, banding with the capacity of accessing with Internet and the requests of performance for industrial and intelligent devices, it makes the total design on the embedded gateway from the software and hardware. In the hardware design, it adopted the 32-bit CPU that specially used in the networks, in which the Ethernet controller is integrated. It provides the high-performance, high- reliability and low-cost hardware platform. In the software design, it adopted the three-layer structure, and applies the embedded operating system—uCLinux that is characterized by the excellent networks performance and the GNU developing tools. The development of the embedded networks application software is based on the integrated TCP/IP protocol set which is integrated in Linux and the APIs that are used in the networks programming. By doing this, it improves the stability of the gateway system and the rate of developing the upper software.During the process of developing the upper software, to the kernel software of the gateway—the embedded Web server, it improves the rate of response, enlarges the area of application and enhances the security of system, which is started with the pivotal technologies, such as, resource allocating, process scheduling, dynamic Web skill—CGI and security etc. When the security mode is designed, it brings forward the "tightsecurity mechanism" which is adaptive in the embedded gateway, according to the special applications and the threats that exist in the gateway system using in the electric system. It adopts the secure policies that are HTTP summary authentication, SSL secure socket protocol and authentic console to defend the different-rank resources.During the process of developing the CAN bus mode, it adopts the high-performance CAN controller—MCP2510, and designs the CAN drivers based on the embedded Linux, including the devices initialization, data I/O access and interrupt service routine. Then it is optimized on the rate of data transmitting and reliability, and it makes the corresponding rules of CAN application layer to ensure the expansibility and compatibility.Finally, according to the targets of system, build the testing and running environment, and choose the testing tools and design the testing scheme. Then it analyzes and quantifies the targets of the embedded and secure Web gateway based on the results of testing.
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