File Transfer Protocol, the protocol for exchanging files over the Internet. FTP works in the same way as HTTP for transferring Web pages from a server to a user's browser and SMTP for transferring electronic mail across the Internet in that, like these technologies, FTP uses the Internet's TCP/IP protocols to enable data transfer.
FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server (e.g., uploading a Web page file to a server).
File Transfer Protocol (FTP) is a standard network protocol used to transfer files from one host to another host over a TCP-based network, such as the Internet. It is often used to upload web pages and other documents from a private development machine to a public web-hosting server. FTP is built on a client-server architecture and uses separate control and data connections between the client and the server.FTP users may authenticate themselves using a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it.
The first FTP client applications were interactive command-line tools, implementing standard commands and syntax. Graphical user interface clients have since been developed for many of the popular desktop operating systems in use today, including general web design programs like Microsoft Expression Web, and specialist FTP clients such as CuteFTP.
FTP may run in active or passive mode, which determines how the data connection is established. In active mode, the client sends the server an IP address and port number and then waits until the server initiates the TCP connection. In situations where the client is behind a firewall and unable to accept incoming TCP connections, passive mode may be used. In this mode, the client sends a PASV command to the server and receives an IP address and port number from the server, which the client then uses to open a data connection to the server. Both modes were updated in September 1998 to support IPv6. Further changes were introduced to the passive mode at that time, updating it to extended passive mode.
Where FTP access is restricted, an FTPmail service can be used to circumvent the problem. An e-mail containing the FTP commands to be performed is sent to an FTPmail server, which parses the incoming e-mail, executes the requested FTP commands and sends back an e-mail with any downloaded files as attachments. This service is less flexible than an FTP client, as it is not possible to view directories interactively or to issue any modify commands. There can also be problems with large file attachments not getting through mail servers. The service was used in the days when some users' only internet access was via e-mail through gateways such as a BBS or online service. As most internet users these days have ready access to FTP, this procedure is no longer in widespread use.
