This XK0-005 practice question tests your understanding of security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An administrator wants to restrict SSH access to only users in the 'sshusers' group. Which configuration should be added to /etc/ssh/sshd_config?
AllowUsers sshusers
Why wrong: This allows a user named 'sshusers', not the group.
DenyUsers sshusers
Why wrong: This denies users in the group, not allows.
AllowGroups sshusers
This allows only users in the sshusers group.
PermitRootLogin no
Why wrong: This disables root login, not group-based access.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AllowGroups sshusers
Option C is correct because the `AllowGroups` directive in `/etc/ssh/sshd_config` restricts SSH login to users who are members of the specified group. By setting `AllowGroups sshusers`, only users belonging to the 'sshusers' group will be permitted to authenticate via SSH, while all others are denied. This matches the administrator's requirement precisely.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
AllowUsers sshusers
Why it's wrong here
This allows a user named 'sshusers', not the group.
DenyUsers sshusers
Why it's wrong here
This denies users in the group, not allows.
AllowGroups sshusers
Why this is correct
This allows only users in the sshusers group.
Related concept
Read the scenario before looking for a memorised answer.
PermitRootLogin no
Why it's wrong here
This disables root login, not group-based access.
Common exam traps
The trap here is that candidates confuse `AllowUsers` (which matches usernames) with `AllowGroups` (which matches group names), leading them to incorrectly select Option A thinking it applies to the group name.
Detailed technical explanation
Under the hood, OpenSSH's `AllowGroups` and `DenyGroups` directives use the system's group membership (via `getgrnam` and `initgroups`) to evaluate access at authentication time. A subtle behavior is that group names are case-sensitive and must match exactly as defined in `/etc/group`. In real-world scenarios, combining `AllowGroups` with `DenyUsers` can create granular access control, but `AllowGroups` alone is sufficient for group-based restriction.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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FAQ
Security — This question tests Security — Read the scenario before looking for a memorised answer..
The correct answer is: AllowGroups sshusers — Option C is correct because the `AllowGroups` directive in `/etc/ssh/sshd_config` restricts SSH login to users who are members of the specified group. By setting `AllowGroups sshusers`, only users belonging to the 'sshusers' group will be permitted to authenticate via SSH, while all others are denied. This matches the administrator's requirement precisely.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This XK0-005 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 XK0-005 exam.
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