Which of the following protocols provides transport security for virtual terminal emulation?

A.
TLS

B.
SSH

C.
SCP

D.
S/MIME

Explanation:
Secure Shell (SSH) is a tunneling protocol originally designed for Unix systems. It uses encryption to
establish a secure connection between two systems. SSH also provides alternative, security-equivalent
programs for such Unix standards as Telnet, FTP, and many other communications-oriented applications.
SSH is available for use on Windows systems as well. This makes it the preferred method of security for
Telnet and other cleartext oriented programs in the Unix environment.
Incorrect Answers:
A: TLS is used to provide a secure channel, not to establish a telnet connection.
The Secure Socket Layer (SSL) and Transport Layer Security (TLS) is the most widely deployed security
protocol used today. It is essentially a protocol that provides a secure channel between two machines
operating over the Internet or an internal network.
C: Secure copy or SCP is a means of securely transferring computer files between a local host and a
remote host or between two remote hosts. It is based on the Secure Shell (SSH) protocol. SCP is not used
to establish a telnet connection.
D: S/MIME is for e-mail and other electronic messaging applications, not for telnet connections.
S/MIME provides the following cryptographic security services for electronic messaging applications:
authentication, message integrity, non-repudiation of origin (using digital signatures), privacy and data
security (using encryption).

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 75, 76, 91, 270, 271