The mechanism of FTP (File Transfer Protocol) involves the transfer of files between a client and a server over a network. FTP operates using a client-server architecture, where the client initiates a connection to the server to request file transfers. The protocol uses two separate channels: a command channel for sending control commands and receiving responses, and a data channel for the actual transfer of files. The client can upload files to the server, download files from the server, and perform various file operations such as listing directories and deleting files.
The working mechanism of FTP begins with the client establishing a connection to the server on the command port, usually port 21. The client sends commands to the server to perform specific actions, such as logging in with a username and password, navigating directories, and requesting file transfers. Once a file transfer is requested, the server opens a data channel on a separate port to handle the transfer of the file. This can be done in two modes: active mode, where the server initiates the data connection back to the client, and passive mode, where the client initiates the data connection to the server.
FTP works internally by using the TCP/IP protocol suite to ensure reliable delivery of data. The client sends FTP commands over the command channel to the server, which interprets the commands and performs the requested actions. For file transfers, the server opens a data channel and uses it to send or receive the file data. The protocol supports various commands for file operations, including RETR (retrieve a file), STOR (store a file), and LIST (list directory contents). FTP also handles user authentication and directory navigation through specific commands and responses.
The three types of FTP are:
- Anonymous FTP: Allows users to access files without requiring a username and password. It is commonly used for public file sharing, where users log in with a generic username, often “anonymous,” and their email address as the password.
- Password-Protected FTP: Requires users to provide a valid username and password to access the server. This type is used for more secure and restricted access to files, ensuring that only authorized users can transfer files.
- FTP Secure (FTPS): Adds a layer of security to the standard FTP protocol by using SSL/TLS encryption for both the command and data channels. This ensures that the data transferred between the client and server is encrypted and secure from eavesdropping or tampering.
