Which of the following is a commonly used protocol for securely transferring files over a network?

Secure Shell (SSH) is a cryptographic network protocol designed for secure communication over an unsecured network. It provides a secure channel for various network services, including remote command-line login and file transfers. Specifically, protocols like SSH File Transfer Protocol (SFTP) and Secure Copy Protocol (SCP) operate over the SSH protocol to provide robust authentication and encryption, ensuring the confidentiality and integrity of files during transfer. This makes SSH the foundational protocol for common secure file transfer operations in modern networking.

A. RDP (Remote Desktop Protocol) is primarily used for secure remote graphical desktop access, not as a standard protocol for file transfers.
B. Telnet is an outdated and insecure protocol that transmits all data, including usernames and passwords, in clear text.
D. FTP (File Transfer Protocol) is inherently insecure as it transmits credentials and data in clear text by default.

1. IETF RFC 4251, "The Secure Shell (SSH) Protocol Architecture": Section 1, "Introduction," states, "SSH is a protocol for secure remote login and other secure network services over an insecure network... It provides confidentiality and integrity of data... The protocol is intended to be used for such purposes as secure remote login, secure file transfer, and secure remote command execution."

2. ArubaOS-CX 10.11 Fundamentals Guide: In the "Management Access" chapter, under the "Secure Shell" section, it details that "SSH provides secure, encrypted access to the switch CLI... The switch also supports SCP and SFTP for secure file transfers." This confirms SSH's role in secure file transfer within the HPE Aruba ecosystem.

3. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.): Chapter 8, "Security in Computer Networks," discusses SSH as a critical application-layer security protocol. It explains that SSH provides services like secure file transfer (via SFTP) by creating an encrypted tunnel between a client and a server.