FTP Server

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What Does FTP Server Mean?

The primary purpose of an FTP server is to allow users to upload and download files. An FTP server is a computer that has a file transfer protocol (FTP) address and is dedicated to receiving an FTP connection. FTP is a protocol used to transfer files via the internet between a server (sender) and a client (receiver). An FTP server is a computer that offers files available for download via an FTP protocol, and it is a common solution used to facilitate remote data sharing between computers.


An FTP server is an important component in FTP architecture and helps in exchanging files over the internet. The files are generally uploaded to the server from a personal computer or other removable hard drives (such as a USB flash drive) and then sent from the server to a remote client via the FTP protocol.

An FTP server needs a TCP/IP network to function and is dependent on the use of dedicated servers with one or more FTP clients. In order to ensure that connections can be established at all times from the clients, an FTP server is usually switched on; up and running 24/7.

An FTP server is also known as an FTP site or FTP host.

Techopedia Explains FTP Server

Although the FTP server actually sends files over the internet, it generally acts as the midpoint between the real sender of a file and its recipient. The recipient must access the server address, which can either be a URL (e.g., ftp://exampleserver.net) or as a numeric address (usually the IP address of the server). All file transfer protocol site addresses begin with ftp://. FTP servers usually listen for client connections on port 21 since the FTP protocol generally uses this port as its principle route of communication. FTP runs on two different Transmission Control Protocol ports: 20 and 21. FTP ports 20 and 21 must both be open on the network for successful file transfers.

Role of the FTP Server

The FTP server allows the downloading and uploading of files. The FTP server’s administrator can restrict access for downloading different files and from different folders residing in the FTP server. Files residing in FTP servers can be retrieved by common web browsers, but they may not support protocol extensions like FTPS. With an FTP connection, it is possible to resume an interrupted download that was not successfully completed; in other words, checkpoint restart support is provided.

For the client to establish a connection to the FTP server, the username and password are sent using USER and PASS commands. Once accepted by the FTP server, an acknowledgment is sent to the client and the session can start. Failure to open both ports 20 & 21 prevents the full back-and-forth transfer from being made.

The FTP server can provide connection to users without login credentials; however, the FTP server can authorize these to have only limited access. FTP servers can also provide anonymous access. This access allows users to download files from the servers anonymously but prohibits uploading files to FTP servers.

Beyond routine file transfer operations, FTP servers are also used for offsite backup of critical data. FTP servers are quite inexpensive solutions for both data transfer and backup operations, especially if security is not a concern. However, when simple login and authentication features are not sufficient to guarantee an adequate degree of security (such as when transferring sensitive or confidential information), two secure file transfer protocol alternatives, SFTP and FTP/S, are also available. These secure FTP server options offer additional levels of security such as data encryption.


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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.