File Transfer Protocol(FTP)

Introduction

• FTP stands for File Transfer Protocol.
• FTP was widely used in the past for transferring files between computers over the Internet, but it has largely been replaced by more secure and efficient protocols such as SFTP (Secure File Transfer Protocol) and HTTPS (Hypertext Transfer Protocol Secure).

Definition

• FTP is a standard network application layer protocol used for transferring files between a client and a server on a computer network or from one host to another over a TCP/IP-based network, such as the Internet.

Characteristics

• It is one of the oldest and most widely used protocols for file transfer and is still in use today, although it has largely been superseded by more secure protocols like SFTP and FTPS.
• FTP operates on a client-server model, where the client establishes a connection to the server and requests to transfer files. Once the connection is established, the client can upload or download files to or from the server using a set of commands and responses defined in the FTP protocol.

Structure

• FTP consists of two parts –

• • FTP clients, such as FileZilla, WinSCP, or Cyberduck, are software programs that allow users to connect to an FTP server and send commands to the server to upload or download or transfer files. FTP clients are available, both free and paid, for various operating systems
  • FTP servers, such as vsftpd, Pure-FTPd, or ProFTPD, are software programs that run on a server and provide file transfer services to clients.
• FTP operates on two channels: a command/control channel and a data channel. The command channel is used to send commands and responses between the client and the server, while the data channel is used to transfer the actual data or files.
• The default port number for the FTP (File Transfer Protocol) protocol is 21. This is the port used for the control connection between the FTP client and server, which is used for commands and responses.

  However, FTP also uses a secondary data channel/connection for file transfers, which can use a range of different port numbers depending on the configuration. However, FTP can also use other port numbers, such as 20 for data transfer in active mode or port numbers in the range of 1024 to 65535 for passive mode data transfers which are assigned randomly. 

  In some cases, FTP servers may also be configured to use a different port number for the control connection, but this is less common.

Working Mechanism

• To use FTP, we need an FTP client software installed on the computer. Once we have an FTP client, we can connect to an FTP server by entering the server’s hostname, username, and password.
• We can then browse the remote files and folders, upload or download files, and perform other file management tasks.

Advantages

• FTP is a simple and widely used protocol.

Disadvantages

• FTP is an old protocol and has some security vulnerabilities, such as transmitting data or login credentials in plaintext, which can be intercepted by attackers. For this reason, it is often recommended to use a secure alternative, such as SFTP (Secure File Transfer Protocol) or FTPS (FTP over SSL/TLS), which use encryption to protect data in transit.

Function/Use

• FTP allows users to upload and download files, create and delete directories, and perform other file management tasks to and from a remote server.
• FTP is commonly used to upload or download files to and from a remote server, such as a web server.
• FTP is often used for transferring large files, such as software updates, multimedia files, or large datasets.
• FTP is also used for website maintenance, as webmasters often use FTP to upload new pages or files to their websites.