Yes, FTP (File Transfer Protocol) uses TCP (Transmission Control Protocol). It relies on TCP to ensure reliable and ordered data transfer between the client and the server.
How FTP Uses TCP
FTP utilizes TCP for its communication. This is not a single connection, but rather two separate TCP connections:
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Control Connection (Port 21): This connection handles the commands and responses between the client and the server. It manages file transfers, logins, and directory navigation. Think of it as the "conversation" about what files to transfer.
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Data Connection (Port 20 or a dynamically assigned port): This connection is used for the actual transfer of the files themselves. The control connection establishes this data connection, determining the port to use and the way it will be handled (active or passive mode). This connection is responsible for transmitting the file contents.
The use of TCP ensures that all data packets arrive correctly and in order. Unlike UDP (User Datagram Protocol), which offers speed over reliability, TCP prioritizes reliability, making it suitable for file transfers where data integrity is crucial. This is why FTP, requiring accurate file transfers, uses TCP.
Several sources confirm this:
- Cerberus FTP: "[W]hen an FTP client requests to connect to an FTP server, a TCP connection is being established..." This highlights the fundamental use of TCP.
- Cisco Learning Network: "FTP uses two TCP connections for communication. One to pass control information... and one to send files." This clarifies the dual-connection approach and their roles within TCP.
- GoAnywhere MFT: "FTP is a file transfer protocol...whereas TCP is a communication protocol used to..." This directly contrasts the protocols and their roles.
- Quora: "FTP is located in the application and runs on top of TCP. FTP uses two TCP connections..." This further reinforces the dependence of FTP on TCP.
- ESA's Cosmos: "FTP is a TCP based service exclusively. There is no UDP component to FTP..." This explicitly states FTP's exclusive reliance on TCP.
- TechTarget: "FTP (File Transfer Protocol) is used to transfer files over TCP/IP." This confirms the protocol pair used for FTP.
In summary, FTP's reliance on TCP is crucial for its reliable file transfer capabilities. The use of two TCP connections efficiently handles control and data transfer aspects of the protocol.
