Secure Shell (SSH) is a cryptographic network protocol designed for operating network services securely over an unsecured network. Its primary use is for secure remote login and command-line execution on network devices like routers, switches, and servers. SSH establishes an encrypted channel between the client and the server, ensuring that all data, including login credentials and console commands, is protected from eavesdropping and tampering. This directly fulfills the requirement to encrypt all data communications when logging into a device's console.

B. LDAP: Lightweight Directory Access Protocol (LDAP) is used for accessing and maintaining directory information services, not for remote console login on network devices.

C. FTPS: File Transfer Protocol Secure (FTPS) is a protocol used exclusively for secure file transfers, not for interactive console sessions or device management.

D. SMTP: Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending electronic mail and is not used for remote device administration.

1. Ylonen

T.

& Lonvick

C. (Eds.). (2006). The Secure Shell (SSH) Protocol Architecture. IETF RFC 4251. Section 1

Introduction. "The Secure Shell (SSH) is a protocol for secure remote login and other secure network services over an insecure network." Retrieved from https://doi.org/10.17487/RFC4251

2. Cisco Systems

Inc. (2023). Secure Shell Configuration Guide

Cisco IOS XE Gibraltar 16.12.x. Chapter: Configuring Secure Shell. "Secure Shell (SSH) is a protocol that provides a secure

remote connection to a device... SSH provides a more secure alternative to Telnet for remote management."

3. Saltzer

J. H.

& Kaashoek

M. F. (2009). Principles of Computer System Design: An Introduction. Morgan Kaufmann. Chapter 9.4.2

Secure Shell (SSH). "SSH provides a secure channel over an unsecured network in a client-server architecture

connecting an SSH client application with an SSH server. Common applications include remote command-line

login

and remote command execution..." (This is a widely used textbook in university computer science curricula

including at MIT).