Network Security Multiple Choice Questions on “Secure Shell(SSH)”.
1. Which of the following is not a secure shell protocol?
a) Transport Layer Protocol
b) Secure Layer Protocol
c) Connection Protocol
d) User Authentication Protocol
Answer: b
Clarification: SSH is organised as three protocols – Transport Layer Protocol, User Authentication Protocol and Connection Protocol.
2.Which is the lowest level in the SSH protocol stack?
a) SSH Transport Layer Protocol
b) TCP
c) IP
d) SSH User Authentication Protocol
Answer: c
Clarification: The IP is the lowest level in SSH the protocol stack.
3. How many trust models does the RFC 4251 dictate?
a) 2
b) 3
c) 4
d) 5
Answer: a
Clarification: The RFC 4251 dictates two alternative trust models : The local database model and the certification authority model.
4. Which is the correct order of the SSH Transport Layer Protocol Packet Exchanges?
a) Algorithm Negotiation; End of key exchange; Service request; Identification string exchange
b) Identification string exchange; Algorithm Negotiation; End of key exchange; Service request
c) Identification string exchange; End of key exchange; Service request; Algorithm Negotiation
d) Algorithm Negotiation; Identification string exchange; End of key exchange; Service request
Answer: b
Clarification: The correct order is: Identification string exchange; Algorithm Negotiation; End of key exchange; Service request.
5. The correct order of operations in the SSH Transport Layer Protocol Packet Formation is –
a) Compression; Encryption; Padding and Addition of seq bits
b) Compression; Padding and Addition of seq bits; Encryption
c) Encryption; Padding and Addition of seq bits; Compression
d) Padding and Addition of seq bits; Encryption; Compression
Answer: b
Clarification: The correct order of operation is – Compression; Padding and Addition of seq bits; Encryption.
6. Size of the sequence number is-
a) 32 bits
b) 48 bits
c) 56 bits
d) 64 bits
Answer: a
Clarification: The seq# is 32 bits.
7. Which one of the following does not undergo the encryption procedure?
a) pdl
b) pktl
c) seq#
d) padding
Answer: c
Clarification: The seq# 32 bits does not undergo encryption.
8. What is the recommended cryptographic algorithm for the Secure Shell Transport Layer?
a) twofish 128
b) aes 192
c) aes 128
d) blowfish
Answer: c
Clarification: aes 128 is the reccomended cryptographic algorithm.
9. What is the recommended modes of operation for encryption and decryption in the Secure Shell Transport Layer?
a) ECB
b) OFB
c) CBC
d) CFB
Answer: c
Clarification: The cipher block chaining mode is the recommended mode of operation in the SSH Transport layer.
10. What is the recommended MAC algorithm for the SSH Transport Layer?
a) HMAC – MD5
b) HMAC – MD5 – 96
c) HMAC SHA1 – 96
d) HMAC SHA1
Answer: c
Clarification: The recommended MAC algorithm for the SSH Transport Layer is the HMAC SHA1 – 96.
11. The session Identifier remains constant throughout the SSH connection.
a) True
b) False
Answer: a
Clarification: The hash value H servers as a session identifier for this connection. Once computed, the session identifier is not changed, even if the key exchange is performed again for this connection to obtain fresh keys.
12. In the Key generation procedure, the Initialization Vector from the server to client is represented as:
a) HASH(K||H||”C”||session_id)
b) HASH(K||H||”B”||session_id)
c) HASH(K||H||”F”||session_id)
d) HASH(K||H||”D”||session_id)
Answer: b
Clarification: The Initialization Vector from the server to client is given by HASH(K||H||”B”||session_id).
13. Which port forwarding technique intercepts application-level traffic and redirects it from an insecure TCP connections to secure SSH tunnels?
a) Remote Forwarding
b) Local Forwarding
c) Stable Forwarding
d) None of the mentioned
Answer: b
Clarification: This is the function of local forwarding.
14. The protocol ‘POP’ stands for-
a) Personal Office Protocol
b) Post Office Protocol
c) Privacy Overall Protocol
d) Privacy Over Protocol
Answer: b
Clarification: ‘POP’ stands for Post Office Protocol.
15.In which port forwarding technique does the client act on the server’s behalf?
a) Remote Forwarding
b) Local Forwarding
c) Stable Forwarding
d) None of the mentioned
Answer: a
Clarification: In Remote forwarding, the client receives traffic with a given destination port number, places the teaffic on the correct port and sends it to the destination the user chooses.