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10.1. FTP Basics

File transfer protocol(FTP) is a simple way to exchange files between different types of computers on the Internet. FTP is similar to hypertext transfer protocol(HTTP), which transfers web pages and related files, and simple mail transfer protocol(SMTP), which transfers e-mail.

A connection to the Internet and an FTP client program such as Sysax Multi Server is required to connect to an FTP server. An FTP session establishes two connections: a control connection, which remains open as long as the connection remains open; and a data connection, which opens only for file listings, downloads and uploads, and closes after each transfer is complete.

Most FTP servers listen on port 21 for connection requests from FTP client programs. When an FTP client requests to be connected, the FTP server verifies the user ID and password, and, if successful, lets the user log in. Once a user logs in to the remote FTP server, access to the FTP server's file system depends on permissions assigned to directories and folders.

Secure FTP(FTPS) secures the FTP connection using the same secure socket layer(SSL) technology that is used for secure web pages.