What is an FTP Server? – Definition from Techopedia

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 over the Internet between a server (sender) and a client (receiver). An FTP server is a computer that offers files available for downloading via an FTP protocol, and is a common solution used to facilitate remote data exchange between computers.

An FTP server is an important component in the FTP architecture and helps in exchanging files over the Internet. Files are usually 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 FTP protocol.

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

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



FTP server actually sends files over the internet, it usually acts as the middle ground between the actual sender of a file and its recipient. The recipient must access the server address, which can be a URL (for example, 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, as the FTP protocol usually uses this port as its primary communication path. FTP runs on two different Transmission Control Protocol ports: 20 and 21. FTP ports 20 and 21 must be open on the network for file transfers to succeed.

FTP Server Function

The FTP server allows downloading and uploading files. The FTP server administrator can restrict access to download different files and from different folders that reside on the FTP server. Files residing on FTP servers can be retrieved by common web browsers, but they may not support protocol extensions such as FTPS. With an FTP connection, it is possible to resume an interrupted download that did not complete successfully; In other words, checkpoint restart support is provided.

For the client to establish a connection to the FTP server, the user name and password are sent using the USER and PASS commands. Once accepted by the FTP server, an acknowledgment is sent to the client and the session can be started. Failure to open ports 20 and 21 prevents the full round trip transfer from occurring.

The FTP server can

provide connection to users without login credentials; however, the FTP server can authorize users to have limited access. FTP servers can also provide anonymous access. This access allows users to download files from 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 fairly inexpensive solutions for both data transfer and backup operations, especially if security is not a concern. However, when simple login and authentication functions are not sufficient to ensure 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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