Point To Point File Transfer Based On STUN And Cloud Platform

With the rapid development of Internet technology,the original IPv4 address has been unable to meet the growing demand for network services,and then produced NAT technology-its emergence and development strongly alleviated the shortage of IPv4 addresses.But another problem caused by NAT technology is that it hinders the use of point-to-point communication applications.Since the type of NAT has a variety of choices and can be used in actual application,it can be used according to the actual needs,which leads to the lack of universal NAT crossing technology at the present stage.In the current network environment of our country,many families,schools and enterprises are in the internal network after NAT.If the host or other internal network terminal hosts in the outer network want to communicate with the former(such as file transfer),it will be prevented by NAT.Therefore,it is a good idea to study how to transmit the point to point file through NAT.A practical topic.The paper first describes the current research status of NAT traversal,and introduces the main NAT traversal technologies and solutions.Secondly,it introduces the technical principle and corresponding classification of NAT,and analyzes the advantages and disadvantages of different NAT traversal technologies,chooses a terminal-based traversal method,and finally selects a method based on STUN protocol and cloud platform to implement NAT traversal.In practical applications,due to the existence of different types of NAT devices,the networking environment in which both parties have communication needs is complicated and varied.However,most of the existing literature only focuses on one of the scenarios.Considering that the communication party usually does not know the type of NAT in the networking environment of its own and the other party,the paper proposes a NAT traversal technology and solution to adapt to different scenarios.After determining the network environment where the two parties are located,the NAT device is based on both parties.Different types are divided into different scenarios,and corresponding traversal methods are selected to implement point-to-point communication.For asymmetric NAT devices,the paper designs STUN client and server modules to implement NAT traversal.For the scenario where both parties of the communication are behind the same NAT device,the paper proposes a new method to implement peer-to-peer communication,which avoids the delay caused by the traditional loopback threading method.For symmetric NAT,the port prediction methods and port guessing methods proposed by the previous generation will have a certain percentage of failures in practical applications.In view of this situation,the paper proposes the function of building a cloud platform and using the cloud platform to transfer point-to-point files.After completing the NAT traversal,the paper designed a file fragmentation and breakpoint transmission module to implement the file transfer function of both sides of the communication,save the progress of the file transfer at any time,support the download or upload of the file from the point of last interruption,and save the file.Time and space resources share.In order to achieve the purpose of transferring multiple files at the same time,the paper designed a corresponding download process and improved the efficiency.Finally,functional testing and analysis of the designed overall system achieve the expected experimental results.