The Application of UDP Protocol in FTP Services

Abstract: In traditional FTP services, the TCP protocol is mainly used for file transfer, but due to the time-consuming three-time handshake of the TCP protocol, the transmission efficiency is low on long transmission chains. This article introduces the use of UDP protocol for reliable, fast, multi threaded, and multi link file transfer, which effectively solves the contradiction between reliability and high efficiency in traditional file transfer.
Keywords: file transfer; FTP； UDP protocol; Upload; Download; thread 
Chinese Library Classification Number: TP368.1
The main protocol for file transfer in traditional FTP services is TCP protocol. With the increasing popularity of internet applications and people's increasing demands for bandwidth and transmission efficiency, traditional FTP services can no longer meet the growing demand of people. This article introduces the implementation of reliable file transfer based on UDP protocol, which effectively meets the requirements for bandwidth and transmission efficiency.
1 FTP Upload Implementation
1.1 Login to FTP Service
The client connects to the server, and after successful connection, the server returns the string "220 Welcome to FTP Server". The client sends the user command "USER xxx", and Ftpserver returns a string of "331 User name ok, need password". The client sends the password command 'PASS xxx'. Ftpserver returns the string "230 User successfully logged in". The value returned for successful login must be 230 (the above step is to log in to ftpserver using the standard ftp command, both uploading and downloading are the same). The client sends the command "UPUDPBUF 0"
1.2 Creating a UDP transmission link
UPUDPBUF represents the udp upload method, and 0 represents normal transmission. We all use the normal transmission method here. Ftpserver returns the string '200 transfer code Permission'. The client sends' UDPPORT xxxx '. UDPPORT represents the udp port that starts locally, and xxxx represents the port number. Return: "UDPPORT xxxx150 Opening BINARY mode data connection for file transfer Where xxxx is the udp port number on ftpserver.
1.3 File segmentation
reference:
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[2] Ma Yong. Research on UDP based Multicast File Transfer Method [J]. Fujian Computer, 2009 (02)
[3] Zhou Jincai. Design ideas and implementation methods of reliable UDP protocol [J]. Journal of Zhoukou Normal University, 2006 (02)
[4] Feng Hao, Su Lei. A Multithreaded Network File Transfer System Based on TCP [J]. Software Guide, 2008 (08)
[5] Wang Haijun, Liu Caixia, Cheng Dongnian. Analysis and research on a reliable transmission protocol based on UDP [J]. Computer Application Research, 2005 (11)
Author Introduction: Cheng Xiaoen (1984.03-), female, teacher, master's student, majoring in computer application technology, mainly engaged in related work and teaching research in computer application.
Author's unit: Sichuan Business Vocational College, Chengdu 611131
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