Research And Development On Policy Server Based On Trusted Connect Technology

With the rapid expansion of the Internet and the rapid development of network technology, the global information-based has become a major trend, the computer is becoming increasingly important for the people's life and work. However, due to the characteristics of openness and interconnectivity, the Internet is not only changing the way of people's life and enhancing the productivity of enterprises, but also leaving the dangers of information security. The existence of network insecurity makes people have no confidence in the network, thus limiting the further development of network function.In recent years, many security protocols have provided a good protective effect on the networks, but neglecting the protection of the access terminal.In totay's information age, terminal is often the source of creating and storing the important data, malicious code may be parasitic on the client terminal and may well tampered the data before the client requests a network connection, or communicates with the server-side by posing as users after the network connection was extablished. Under such circumstances, to ensure the credibility of terminal is all the more important. Therefore, the original security protocol must be based on more details of safety testing on the terminal.TCG's TNC group brought forward the "The Integrity Measurement of Access Terminals" thinking and the corresponding norms of the "Trusted Network Connect": assess the credibility of terminals requesting access to the network using pre-established security policy and platform configuration. Terminals that don't meet the predetermined security policies will be refused access or isolated for repair, which can prevent the terminal lack of credibility from connecting to the network to implement destructive action, and in consequence greatly enhance the network security and credibility.This paper describes the Trusted Network Connect architecture and its underlying authentication protocol issued by the organization of TCG, and bring forward based on the research into the existing framework of trusted network the concept of policy server and its communication mechanism based on the trusted network connection technology.Policy server is an important component of the framework of trusted network connection, logical entity corresponding to which is PDP in the TNC architecture.Policy server can evaluate different access terminals and grant those that meet the trusted requirement corresponding trusted level and access permission to connect to the trusted network. Moreover, reject or isolate those that do not meet the trusted requirement or have some potential dangers. Finally, test and verify the feasibility and practicality of the policy server using some experimental approaches.Diameter protocol is the next generation of standard AAA protocol proposed by IETF. The biggest advantage of Diameter is its high expansibility, which can define a new Diameter application protocol based on different networks. To deal with requests for access of terminals, Diameter customers communicate with Diameter server using Diameter basis protocol and Diameter application protocol, such a series of information exchange from launch to termination is called a user session in Diameter protocol.PANA protocol runs between the PaC and the PAA in order to complete the process of network access services. Though PANA is based on UDP protocol, but has a well-established retransmit mechanism to ensure the reliability of information transmission. PANA protocol contains a series of request and response messages, which is used in end-to-end certification process, and each message is implemented by zero or more AVP load. EAP message is the main load of PANA and is used for creating EAP session between the PaC and the PAA.This paper combines the PANA protocol and the Diameter protocol to complete the underlying communication process of the TNC architecture. PANA protocol is used for the communication between the PEP and the AR, and that using between PEP and PDP is Diameter protocol. In this way, the use of security mechanisms and re-certification mechanism of Diameter protocol and PANA protocol can not only ensure the security of network effectively, but also request for re-certification on some particulat situation, such as the terminal triggers initiative, network environment changes, request for service arrives. Based on selecting the PANA protocol and the Diameter protocol as load protocols of the bottom layer, we would also have to choose a suitable protocol for the upper layer. Considering that there have more mature realization of the IF-T protocol and IF-TNCCS protocol, and that there is no standard agreement been raised for the IF-M protocol, we choose the original IF-T, IF-TNCCS and self-defined IF-M as load protocol of the upper layer.The implementation of policy server is compliance with the three-layer structure of the TNC architecture. We divide the policy server into four modules from the perspective of functional, namely: NAA-end module, TNCS-end module, IMV-end module and TLD-end module. NAA-end module:its main function is responsible for the communication between the policy server and the PEP, authentication of identity of the AR, receiving the integrity information from AR and submitting it to upper layer for trusted evaluation, and ultimately return the evaluation result to the AR. TNCS-end module: it is the core module, on the one hand, it links up the NAA-end module and the IMV-end module, transfers the authentication information between AR and IMV-end module; On the other hand, it is "decision maker" of the policy server, it grants ARs corresponding trusted level and access permission after receiving all the evaluation results from the IMV-end module. IMV-end module: its main function is to verify the integrity measurement collected by the IMC-end module of AR, and then sends the verify result to the TNCS-end module for access decision-making. TLD-end module: a small but also important module, its main function is to query the LDAP database to make a trusted level for ARs that passed the verification successfully.To make choice of the system development environment, considering that the Linux operating system is widely used as a network server platform, as well as a good visual interface, this paper choose Redhat Enterprise Linux Advanced Server 4 as a platform of the policy server for the main programming and testing work. As a result of reusing of OpenDiameter API class library in the implementa tion of the underlying communication, we choose C++ as the programming language so as to bring other modules into correspondence with the underly ing communication.Due to the constraints of the experiment environment, as well as the realization of the policy server in this paper is the purpose of pre-research prototype system, test cases using in testing process are relatively simple, which still cover every situations or outcome of trusted signature certificate verification and integrity attributes verification. Therefore, the simplificati on of the test case will not affect the validity of test results.