Which application layer protocol is commonly used for secure file transfers on Linux?

SFTP, or Secure File Transfer Protocol, is the correct answer because it is specifically designed to provide secure file transfers over the network. SFTP uses encryption to protect the data being transferred, ensuring that sensitive information is not exposed to interception during transmission. This makes it particularly valuable in secure environments where data integrity and confidentiality are paramount.

Unlike other protocols, SFTP operates over SSH (Secure Shell), which adds an additional layer of security compared to its unsecure counterparts. This protocol allows users to log in to remote systems and securely transfer files while also offering capabilities for file management and secure access control.

HTTP and FTP do not provide encryption by default, making them less suitable for secure file transfers. HTTP is primarily used for web communications, and while it has a secure counterpart (HTTPS), it is not inherently designed for file transfers. FTP itself is a standard file transfer protocol that is not secure unless augmented with other methods, such as FTPS, which is not the same as SFTP. SMTP is associated with email transmission and is also not relevant to file transfers.

Overall, SFTP stands out as the protocol best suited for secure file transfers in Linux environments due to its built-in security features and compatibility with existing SSH infrastructure.