What is ftp?

FTP, or File Transfer Protocol, is a standard network protocol used to transfer files from one host to another over a TCP-based network such as the Internet. Here are some key points about FTP:

1. Purpose: FTP is designed to facilitate the transfer of files between a client and a server on a network. It is commonly used for uploading files to a server, downloading files, and managing file systems over the network.

2. Operation Modes: FTP operates in two basic modes:

   • Active Mode: In this mode, the client opens a random port and listens while the server actively connects to it. The client sends the server its IP address and port number.
   • Passive Mode: In this mode, the server opens a random port and allows the client to connect to it. This mode is often used to solve issues with firewalls and NAT (Network Address Translation) that do not allow incoming connections to the client.

3. Data Representation: FTP supports various data types for transfer, including ASCII, binary, EBCDIC, local byte, and others, to ensure proper file type formatting across different systems.

4. Security Concerns: Standard FTP is not considered secure because it transmits data, user credentials, and commands in plain text over the network. This makes it susceptible to interception and attacks such as man-in-the-middle. To address these concerns, secure variants like FTPS (FTP Secure) and SFTP (SSH File Transfer Protocol) are used.

   • FTPS: An extension of FTP that uses SSL/TLS to encrypt data transmissions.
   • SFTP: Not an extension of FTP, but part of the SSH protocol suite, it provides a secure file transfer method over an SSH connection.

5. Client and Server Software: There are numerous FTP client and server software available, both free and commercial, for various operating systems. Examples include FileZilla, WinSCP, vsftpd, and ProFTPD.

6. Command-Line and GUI: FTP can be accessed and managed using command-line interfaces (CLI) or graphical user interfaces (GUIs), providing flexibility depending on user preference and the complexity of tasks.

7. Standard Ports: FTP traditionally operates over ports 21 for command (control) connection and 20 for data connection in active mode. However, other ports might be used, especially in passive mode.

8. Use Cases: FTP is widely used for website maintenance (uploading web pages and content), transferring large files across networks, automated backups, and data exchange between businesses.

While FTP has been a reliable method for file exchange for decades, its unencrypted nature often leads organizations to use more secure alternatives or apply additional security measures like VPNs or secure tunnels.