Design And Implementation Of Intranet-Extranet Data Exchange Gateway Software

With the rapid development of computer networks, human society has become dependent on the Internet higher and higher. Internet has gone deep into all aspects of our life and has become an important tool for information exchange. However, when people are enjoying the rich Internet resources, network security has become the key issues of network services and applications. Network security has become the lifeline of the enterprise. How to safely and effectively transfer the information, which is in the intranet of the enterprise, to the internet server for users to access is an important issue to be solved in each enterprise.Through the analysis of the network security situation at home and abroad, we found that firewall technology research had made very good achievements in china. But there are many defects of productization the Research results. The most products concentrate with emphasis in the hardware firewall. They neglect the middle and small scale network and individual user products seriously. High-end firewall products are often complex, high cost and also need to have certain professional knowledge. The hardware firewall cost too much and the middle and small scale network and individual user can't afford it. This leads them to become the direct victim of network attack. To design a set of simple and efficient software firewall has the feasibility and practicability. It can be more effective for small network users to enhance network security environment and the actual utilization. The subject of the designed of intranet-extranet data exchange gateway software, which is a sub-topic of " Lightning protection information management system for Changchun". It is used to implement the safety transmission of lightning location data, which is in the intranet data server of Changchun Lightning Protection Center, to the enterprise's Internet data server. It Facilitate the Internet users for data query operation.My topic makes a comparative analysis of the network security mainstream technology. The topic explains the firewall key technologies emphatically, and analyzes the security policy and the basic structure of the firewall. Based on the above analysis of background combining with the actual situation of Lightning Protection Center, the topic gives the hardware structure and software architecture and determines the gateway software design after the detailed analysis of the software's requirement. The design and implementation of intranet-extranet data exchange gateway software in my paper belongs to circuit gateway firewall. The implementation of the software is based on Socket network programming and database programming techniques, using the Object Oriented Programming ideology. The software consists of three main modules (Intranet client program. Gateway program and Extranet server program) and two auxiliary modules (Log and help).These modules realize the intranet-extranet data security transmission by co-operation and interaction. The intranet data server is running the Intranet client program and making the configuration of network information through the software interface. Timing establishes the connection with Gateway program. If it passes the identity authentication, the Intranet client program sends the length of the data file at first to make sure the synchronization of send and receive data. After that, it begins to send intranet data to the Gateway program. It auto disconnect after the data sending finished. When the set time interval reaches, it will automatically re-establish the connection. The gateway host is running the Gateway program and making the configuration of network information through the software interface. The Gateway program opens to accept the connection request and monitors the connection of intranet server. Once the connection requests of the intranet server arrive, the Gateway program verifies its identity (verifies the IP address). If the connection passes the identity authentication, the Gateway program connects the extranet server program immediately, and establishes the TCP connection with Internet server. The Gateway program receives the length of the data file and forward it at first to make sure the synchronization of send and receive data. After that, it begins to receive and forward the intranet data.It auto disconnect with Internet server when the data receive and forward finished. If the connection fails to passes the identity authentication, the Gateway program refuses to receive and forward data by disconnecting with intranet server immediate. The internet server is running the extranet server program and making the configuration of network information through the software interface. The extranet server program opens to accept the connection request and monitors the connection of Gateway program. Once the connection requests of the Gateway program arrive. The Extranet server program agrees the requests immediately and receives the data packet transmitted through the gateway host to achieve the purpose of intranet-extranet data exchange. The paper focuses on explaining the establishment of network connections and implementation of the data forwarding process. And we have verified the correctness of the software through the test of software features and operation stability.