Which of the following protocols uses public-key cryptography to authenticate the remote
computer?
A.
SSH
B.
Telnet
C.
SCP
D.
SSL
Explanation:
Secure Shell (SSH) is a protocol that provides strong authentication and secure
communications over unsecured channels. It uses public key
encryption as the main method for user authentication. SSH secures connections over the Internet
by encrypting passwords and other data.
It also protects networks against IP spoofing, packet spoofing, password sniffing, and eavesdropping.
SSH uses TCP port 22 as the default
port and operates at the application layer.
SSH protocol has the following three components:
1.Transport layer protocol
2.User authentication protocol
3.Connection protocol
Answer option C is incorrect. The SCP protocol sends data in encrypted format. It is used to prevent
potential packet sniffers from extracting
usable information from data packets. The protocol itself does not provide authentication and
security; it relies on the underlying protocol,
SSH, to provide these features. SCP can interactively request any passwords or passphrases required
to make a connection to a remote host,
unlike rcp that fails in this situation.
The SCP protocol implements file transfers only. It does so by connecting to the host using SSH and
there executes an SCP server (scp). The
SCP server program is typically the same program as the SCP client.
Answer option D is incorrect. Secure Sockets Layer (SSL), also known as Transport Layer Security
(TLS) are cryptographic protocols that
provide security for communications over networks such as the Internet. TLS and SSL encrypt the
segments of network connections at the
Transport Layer end-to-end. SSL uses a program layer located between the Internet’s Hypertext
Transfer Protocol (HTTP) and Transport
Control Protocol (TCP) layers.
Answer option B is incorrect. The full form of Telnet is Teletype Network. It is used to connect a
computer to a local network (LAN) or the
Internet. It can also be used for accessing servers by using a valid user name and password. It is a
common way to control Web servers
remotely.