CAS-004 Security Engineering Practice Question
A security administrator is hardening SSH access to a jump host. The requirement is to allow only key-based authentication and restrict the use of weak cryptographic algorithms. Which of the following configurations accomplishes this?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set PubkeyAuthentication yes, PasswordAuthentication no, and configure Ciphers and MACs to strong algorithms only
Setting PubkeyAuthentication yes and PasswordAuthentication no enforces key-only access. Disabling weak ciphers and MACs ensures strong cryptographic algorithms are used. Option A permits password authentication with 'PasswordAuthentication yes'. Option C allows passwords. Option D allows keyboard-interactive, which can include passwords. Only Option B meets both requirements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set PermitRootLogin prohibit-password and PasswordAuthentication yes
Why it's wrong here
Password authentication is allowed.
- ✓
Set PubkeyAuthentication yes, PasswordAuthentication no, and configure Ciphers and MACs to strong algorithms only
Why this is correct
This enforces key-based auth and removes weak ciphers/MACs.
- ✗
Set PasswordAuthentication yes and use a strong password policy
Why it's wrong here
Passwords are allowed, which is against the requirement.
- ✗
Set AuthenticationMethods publickey,keyboard-interactive
Why it's wrong here
Keyboard-interactive may allow passwords.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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