What is FTP? The protocol & important commands

The File Transfer Protocol refers to one of the oldest and most popular protocols for transferring files over IT networks, used in various scenarios in both Local Area Networks (LAN) and global Wide Area Networks (WAN) such as the Internet. It is a reliable and effective standard that, due to its long development and regular implementation of new procedures, can adapt flexibly to different needs and infrastructures. Despite some disadvantages compared to later developments like SAMBA (SMB) or NFS, FTP remains an essential tool, especially in the administration of web hosting and Dedicated Servers or Virtual Private Servers.

How does FTP work and what sets it apart?

FTP allows the user to establish a bidirectional connection between two nodes - the server and the client - and use it for sending and receiving files. To do this, an FTP server (daemon) runs on one side, listening for requests on a specific port. If a client wants to establish a connection, they contact the server and authenticate themselves - if necessary - using a mutually supported method. The software then establishes an additional data channel for the transfer. Based on this principle, FTP has some fundamental features that are based on its technical specifications:

• Compatibility between different software and operating systems
• Support for encrypted authentication and data transfer (FTPS)
• Hierarchical handling of downloads and uploads
• Possibility to configure for anonymous access
• No support for multiple connections during an upload
• Special variant allows booting from remote servers (TFTP)
• Connection with Secure Shell Server (SSH) possible (SFTP)

How secure is file transfer with FTP?

A problem with FTP is that the protocol, due to its age and in favour of maximum compatibility, does not include integrated encryption and transmits communication in plain text. This applies to both files and the control channel, including sensitive data such as usernames and passwords. Therefore, outside of a trusted, local LAN like a home network, FTP must explicitly enable encryption to ensure adequate security. For this purpose, either the protocol Transport Layer Security (TLS, formerly SSL) used for websites can be used as FTPS, or the use of SSH integrated in Unix and Linux as SFTP. The advantage of the latter solution is that SFTP utilises the secure user access of the operating system and the secure encryption of the SSH server used for administration. As a result, SFTP does not require additional configuration on the server or client side to ensure high data security.

What sets FTP apart from other protocols?

Unlike other protocols such as file transfer over HTTPS directly on a website, FTP works very efficiently and consumes little bandwidth to transmit data encapsulation and control commands. This allows for high-speed transmission, although it always occurs exclusively over a single channel. FTP does not support the establishment of multiple parallel connections, for example, to a Dedicated Server with high bandwidth, which could bypass limitations imposed by this single connection. Integration of remote file systems, as done with network drives via SAMBA or NFS and with some cloud storage providers, is only possible to a limited extent. Therefore, using FTP requires specific software as a client and can only be done directly through external programs, such as a local file manager, in exceptional cases.

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What are the best FTP programs?

When using an FTP program, it is important to differentiate between the server and the client. Most servers operate without a graphical interface, focusing on security like vsftpd or functionality like ProFTPD and PureFTPD. On the other hand, clients have software that has been around for decades, aiming for a clear, intuitive interface and excellent user-friendliness. Examples include FileZilla, compatible with all common operating systems, and WinSCP for Microsoft Windows.

Here is our article on the top 5 FTP programs

Photo: Bethany Drouin on Pixabay