Design And Implementation Of Embedded Security Web Gateway Based On PROFIBUS-DP

PROFIBUS is the most popular fieldbus in manufacturing, Process Control andAutomation at present. Based on PROFIBUS, the control network in enterprise connectsthe production devices and equipments together and makes the production process controland monitor centralized. However the tranditional control network is isolated from theinformation network in enterprise, managerial personnel and technical personnel can knowabout the state of production process only by physically visiting the production field orregular reported files. How to make the fieldbus network access to Internet to realizeremote and real-time monitoring and guarantee the information security based on theinterconnection method has become a research hotspot of industrial network technology. Inthis research, an embedded Web gateway is developed for realizing the interconnectionbetween PROFIBUS-DP network and Internet and especially for meeting the securityrequirement. With compact structure and low cost, it paves the way to realize real-timemonitoring PROFIBUS device safely via Internet.Based on the detailed analysis of network structure and network protocol ofPROFIBUS and Internet, a method based on embedded gateway is proposed to realize theinterconnection and communication between two kinds of heterogeneous networks, anddetailed method and model of protocol conversion are also designed.According to the communication model of two kinds of heterogeneous network, thegateway hardware platform is designed with high performance microprocessor S3C2440,high-speed Ethernet controller DM9000, large capacity of SDRAM and FLASH memory,as well as interface of PROFIBUS and Internet. As to software system architecture, theembedded Linux operating system with excellent network performance，the embeddedWeb technology with excellent network friendly interactive ability，the embedded databasetechnology used to manage information are adopted in this design. In terms of system security, security threats are analyzed when PROFIBUS-DPfieldbus network access to Internet via the embedded Web gateway. With the reference ofthe exsiting common security method, three measures are adopted to guarantee systemsecurity, including the idea of mandatory access control used to realize user access control,SSL socket layer protocol used to realize information security transmission, classifiedsystem log used to provide security services.Corresponding CGI application programs are designed to realize interact between userand device, user access control and recording classified system logs. To demonstrate thevalidity of the study and design, some experiments and tests are conducted. Test resultsshow that with the designed embedded secure Web gateway user can realize real-time andclear monitoring PROFIBUS device via Internet, and security measures adopted also canprovide basic security guarantee for system.