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XK0-006 Practice Question: Which THREE of the following actions can help…
Which THREE of the following actions can help prevent unauthorized access to a Linux server via SSH?
⚠ Common exam trap
CompTIA often tests the misconception that increasing `MaxAuthTries` (option B) or using protocol version 1 (option C) improves security, when in fact they either have no preventive effect or actively weaken security.
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
✓
Allow only specific users with AllowUsers.
The `AllowUsers` directive in `/etc/ssh/sshd_config` restricts SSH logins to only the specified user accounts, blocking all others even if they have valid credentials. This reduces the attack surface by explicitly whitelisting authorized users, making it an effective access control measure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Allow only specific users with AllowUsers.
Why this is correct
Restricts SSH access to authorized users.
- ✗
Set MaxAuthTries to 6.
Why it's wrong here
Default is already 6, does not prevent brute force effectively.
- ✗
Use protocol version 1.
Why it's wrong here
Version 1 has known vulnerabilities.
- ✓
Disable password authentication.
Why this is correct
Forces key-based authentication, stronger.
- ✓
Set PermitRootLogin to no.
Why this is correct
Prevents direct root login.
Go deeper
Related to this question
Learn chapter
Linux Fundamentals and History
Key term
User
A user is any person, system, or device that interacts with an IT service, resource, or identity system, typically authenticated through credentials and authorized to perform specific actions.
Key term
SSH
SSH (Secure Shell) is a cryptographic network protocol that provides secure, encrypted communication and remote administration between two devices over an unsecured network.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 practice question is part of Courseiva's free CompTIA 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 XK0-006 exam.