27.1 Introduction
FTP is another commonly used application. It is Internet standard for file transfer.
27.2 FTP Protocol
FTP differs from the other applications that we've described because it uses two TCP connection to transfer a file
Date Representation
Numerous choices are provided in the FTP protocol specification to govern the way the file is transferred and stored. A choice must be made in each of four dimensions.
FTP Commands
The commands and replies send across the control connection between the client and server are in NVT ASCII .
FTP Replies
The repies are 3-digit numbers in ASCII, with an optional message following the number. The intent is that the software needs to look only at the number to determine how to process the reply , and the optional string is for human consumption.
Connection Management
There are three uses for the data connection
Sending a file from the client to the server
Sending a file from the server to the client
Sending a listing of files or directories from the server to the client.
27.3 FTP Examples
Connection Management: Ephemeral Data Port
Connection Management : Default Data Port
Text File Transfer: NVT ASCII Representation or Image?
Aborting A File Transfer: Telnet Synch Signal
Anonymous FTP
Anonymous FTP from an Unknown IP Address
