Mastering FTP, TFTP, and SFTP: When and How to Use Each File Transfer Protocol

FTP (File Transfer Protocol) provides a reliable way to upload and download files between a client and a server using TCP. It uses two connections: a control connection on port 21 that remains open for the session, and a data connection (port 20 in active mode or a random port in passive mode) for transferring files, directory listings, etc.

FTP supports authentication, directory listing, and two transfer modes: ASCII for text files (converting characters to ASCII) and binary for images and program files (no conversion).

Active mode (PORT) – the client sends a PORT command with its temporary port; the server initiates a data connection from its port 20 to the client’s port.

Passive mode (PASV) – the client sends PASV, the server opens a temporary port and informs the client; the client then connects to that port for data transfer.

TFTP (Trivial File Transfer Protocol) is a simple, UDP‑based protocol (port 69) for transferring files without authentication, directory listings, or complex interactions. It is suitable for environments where only basic upload/download is needed.

SFTP (Secure File Transfer Protocol) runs over SSH (default port 22) and provides encrypted, authenticated file transfer. It offers higher security than FTP but incurs lower performance due to encryption overhead.

Understanding the differences between these protocols helps you choose the appropriate method for your security, performance, and network requirements.