LPIC-2 System Security Practice Question
A system administrator wants to ensure that only key-based authentication is allowed for SSH and password authentication is disabled. Which configuration change is required in /etc/ssh/sshd_config?
⚠ Common exam trap
Candidates often think disabling password authentication alone is sufficient (Option D), forgetting that explicitly enabling public key authentication is necessary to ensure key-based login works and to avoid ambiguity in environments where defaults may differ.
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
✓
PasswordAuthentication no and PubkeyAuthentication yes
Setting `PasswordAuthentication no` disables password-based login, while `PubkeyAuthentication yes` enables public key authentication. Together, these directives ensure that only users with a valid SSH key pair can authenticate, meeting the requirement to disable password authentication entirely.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
PasswordAuthentication yes and PubkeyAuthentication yes
Why it's wrong here
This allows both password and key authentication, not disabling passwords.
- ✗
PasswordAuthentication no and PubkeyAuthentication no
Why it's wrong here
This disables all authentication methods, preventing any login.
- ✓
PasswordAuthentication no and PubkeyAuthentication yes
Why this is correct
This disables password logins and enables key-based authentication, meeting the requirement.
- ✗
PasswordAuthentication no
Why it's wrong here
Only disabling passwords is insufficient; key auth must be explicitly enabled.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 practice question is part of Courseiva's free LPI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LPIC-2 exam.