SFTP and SCP: Secure File Transfer

Despite its name, SFTP (SSH File Transfer Protocol) has nothing to do with FTP. It is a binary protocol designed to run as an SSH-2 subsystem, meaning it operates over an existing authenticated and encrypted SSH connection. The SSH client invokes the SFTP subsystem on the server with the command ssh user@host -s sftp. All SFTP operations inherit the security guarantees of the underlying SSH transport.

SFTP provides a rich set of file operations over the encrypted channel: listing directory contents, uploading files, downloading files, deleting and renaming files, creating and removing directories, reading and setting file permissions and timestamps, and resuming interrupted transfers. These capabilities make SFTP a complete remote file system interface, not merely a file transfer tool.