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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)                 9  TCP/IP General File Transfer Protocols (FTP and TFTP)                      9  File Transfer Protocol (FTP)

FTP Data Representation: Data Types, Data Structures and Format Control 1 FTP Internal Protocol Commands and Command Groups

In the previous section I discussed the general operation of the File Transfer Protocol. As part of this description I explained how data transfers are performed, how connections are established and managed, and the various transmission modes and data types that FTP supports. All of these functions are implemented using a special set of FTP commands sent by the User-FTP process to the Server-FTP process. The server device acknowledges commands by sending back replies using special codes. Understanding FTP commands and reply codes will allow us to see fully how the protocol works.

I begin the section by discussing FTP commands and how they are grouped. I then show the special encoding format used for FTP reply codes, and list some of the more common and important codes. I also discuss the FTP user interface and the commands used by typical FTP implementations to allow a user to communicate with the FTP software. These commands are usually different than the internal FTP commands, to allow the user to operate the protocol in a way more friendly to humans.

FTP Data Representation: Data Types, Data Structures and Format Control 1 FTP Internal Protocol Commands and Command Groups