Linux+ V8 SSH Hardening and Key Management

1. Which encryption algorithm is considered weak and should be disabled in SSH?

AES-128

AES-256

3DES

ChaCha20

2. Which SSH configuration file is primarily used for server settings?

/etc/ssh/ssh_config

/etc/ssh/sshd_config

~/.ssh/config

/var/ssh/config

3. What is the purpose of SSH key passphrases?

To encrypt private keys at rest

To increase connection speed

To simplify key management

To authenticate the server

4. Which directive specifies the maximum number of authentication attempts?

MaxAuthTries

MaxLoginAttempts

AuthRetries

FailedLoginLimit

5. What is the typical format of an SSH public key file?

Binary encoded data

Base64-encoded text starting with ssh-rsa or ssh-ed25519

Hexadecimal hash

Encrypted plaintext

6. Which protocol should replace SSH version 1 for security purposes?

Telnet

SSH version 2

FTP

Rlogin

7. What does the PermitRootLogin directive control?

Whether root can log in via SSH

The password for root access

Root user file permissions

Root process priority

8. Which SSH configuration option enables public key authentication?

PubkeyAuthentication yes

EnablePublicKey true

AllowPubkey yes

PublicKeyAuth enable

9. How should SSH private key files be protected?

Readable by everyone

600 permissions (owner read/write only)

644 permissions

755 permissions

10. What is the purpose of ssh-keygen?

To generate SSH key pairs

To encrypt SSH connections

To authenticate users

To manage SSH processes

11. Which SSH protocol version should be used to ensure modern security standards?

SSH version 1

SSH version 2

SSH version 3

SSH version 4

12. What does disabling root login via SSH accomplish?

Prevents password brute-force attacks on root

Eliminates all remote access

Improves system performance

Reduces SSH port usage

13. Which directive in sshd_config restricts SSH access to specific users?

AllowUsers

PermitUsers

AuthorizedUsers

ValidUsers

14. What is the default SSH listening port?

20

22

2222

3389

15. Which SSH key type provides the best security for new implementations?

RSA

DSA

ECDSA

Ed25519

16. What does the PubkeyAuthentication directive control in sshd_config?

Whether public key authentication is enabled

The location of public key files

The encryption algorithm for keys

The number of public keys allowed

17. Which file stores authorized public keys for SSH access?

/etc/ssh/authorized_keys

~/.ssh/authorized_keys

/home/.ssh/public_keys

/var/ssh/auth_keys

18. What is the recommended key size for RSA SSH keys to meet current security standards?

512 bits

1024 bits

2048 bits or larger

4096 bits maximum

19. Which configuration directive disables SSH password authentication?

PasswordAuthentication no

DisablePassword yes

AllowPassword false

NoPasswordAuth enable

20. What is the primary purpose of SSH key pairs in authentication?

To replace passwords with asymmetric cryptography