FTP (File Transfer Protocol) has become a staple of how data is transferred across the internet. It is a reliable, secure, and efficient way to move files from one location to another. Whether you are transferring data for business or personal use, FTP is an essential tool for the job. 

In this article, we will take a deep dive into FTP, exploring its types, how it works, and its history.

What is FTP?

File Transfer Protocol (FTP) is a standard network protocol used to transfer files between computers on a TCP/IP network. It is a client-server protocol that utilizes separate control and data connections between the client and the server.

FTP can be used to transfer entire directory structures containing multiple files of any type. It is common for websites to use FTP to upload and download files such as documents, images, videos, music, and software.

For example, a user might use FTP to upload a web page to a remote web server. The user would connect to the server using an FTP client, upload the web page to the server, and then disconnect. The web page would then be accessible to other users who visit the website.

How Does FTP Work?

FTP works by establishing a connection between two computers, typically known as a client and a server. The client computer is the one sending the file to the server, and the server is the one receiving the file.

For a client to connect to a server, it must first send a request to the server. This request includes the name of the server, the username, and password of the user, and the name of the file to be transferred.

Once the server receives the request, it will authenticate the user’s credentials and establish a connection. The server then sends a response back to the client, confirming the connection and providing the client with the necessary information to send the file.

Once the connection is established, the client can begin sending the file to the server. The server will acknowledge each packet of data that it receives, and the client will continue sending until the entire file has been transferred.

In addition to downloading and uploading files, FTP also allows users to create, delete, and rename files and directories on the server. It also allows users to view the directory structure on the server and set permissions and ownership for files on the server.

Once the file transfer is complete, the server will send a confirmation to the client to indicate that the file was successfully transferred. The client can then disconnect from the server, and the connection will be terminated.

FTP is considered a reliable protocol since it verifies the integrity of the data being transferred. It also supports secure connections and encryption, allowing users to transfer files securely over the network.

The client and server will negotiate the transfer mode when a connection is established. The two modes are active mode and passive mode.

• Active Mode: In active mode, the client computer makes a connection to the server and then sends commands to the server. 

• Passive Mode: In passive mode, the client computer sends a command to the server, and then the server sends back a connection request. The client then responds to the request with a connection.

Users can use FTP in several ways, such as through a command-line interface from a console or terminal window in Microsoft Windows, Apple macOS or Linux, or a dedicated graphical user interface. Alternatively, web browsers can be used as FTP clients for easy access.

Types of FTP

There are various types of FTP, including:

1. Anonymous FTP: Anonymous FTP is a type of FTP that allows a user to access files on a remote server without supplying a username or password. Instead, the user logs in using the username “anonymous” and a password of their choosing. Anonymous FTP is mainly used for public file sharing, such as software downloads and other resources which are available to the general public. Anonymous FTP is generally considered the least secure type of FTP, as it requires no authentication and can be used to transfer large amounts of data.

2. FTP Secure (FTPS): FTP Secure (FTPS) is an extension to the File Transfer Protocol (FTP) that adds support for the Transport Layer Security (TLS) and the Secure Sockets Layer (SSL) cryptographic protocols. FTPS is used to secure the data transfer between two computers. It is commonly used to securely transfer data such as sensitive personal information, financial information, and other confidential data. FTPS provides authentication of the two computers involved in the data transfer, as well as encryption of the data during the transfer. This helps to ensure that the data being transferred is secure and protected from interception or manipulation.

3. Password-protected FTP: Password-protected FTP is a type of File Transfer Protocol (FTP) that requires a username and password to gain access to the server. It is most commonly used to securely transfer files between two computers over the Internet. The server hosting the files generally requires authentication from the client before any files can be transferred. A secure connection is established using an encryption protocol, such as Secure Sockets Layer (SSL) or Transport Layer Security (TLS). This ensures that all data sent between the client and server is encrypted and cannot be easily intercepted. Password-protected FTP is a secure and effective way to transfer files between two computers.

4. FTP over explicit SSL/TLS (FTPES): FTP over explicit SSL/TLS (FTPES) is a secure version of File Transfer Protocol (FTP). FTPES uses an SSL/TLS layer to encrypt the control and data channels to ensure the secure transmission of data between the client and the server. This is the most secure form of FTP and is often used to transfer sensitive information, such as financial data. It is also useful for transmitting files across untrusted networks, such as the Internet. FTPES requires both the client and server to support SSL/TLS and must be explicitly enabled on the server for the secure connection to be established.

5. Secure FTP (SFTP): Secure FTP (SFTP) is an FTP protocol that provides an encrypted connection for transferring files over the internet. It uses the Secure Shell (SSH) protocol to establish a secure connection and uses strong encryption techniques to protect the data during the transfer. SFTP also provides additional features, such as authentication and access control, which help to protect your data from unauthorized access. SFTP is widely used in enterprise networks and is becoming increasingly popular for transferring files over the internet.

History of FTP

FTP was initially designed to make file transfers possible via ARPANET, the internet’s precursor. FTP was first developed as RFC 114 on April 16, 1971, by Abhay Bhushan, a computer scientist at MIT. 

Several changes were made to the FTP specification to comply with networking standards, particularly TCP/IP, as the modern internet started to take shape. 

At the time, Jon Postel, a research scientist at the University of Southern California’s Information Sciences Institute, specified a new version of FTP in RFC 765 in 1980. 

RFC 959, which added additional management features for the protocol and gave it the ability to create and remove file directories, redefined FTP once more five years later. 

The main function of earlier versions of FTP was to move files to and from already-existing file directory structures.

RFC 959 was updated in 1997 to provide additional security features defined in RFC 2228. Two years later, RFC 2428, an upgrade to FTP, included support for IPv6.