The correct answer is `firewall-cmd --add-rich-rule='rule family="ipv4" source address="10.10.10.0/24" service name="ssh" accept'`. This rich rule is correct because it uses the explicit `source address` parameter to restrict SSH to a subnet, combined with the `service name="ssh"` and `accept` action, giving you granular control over traffic without affecting other services. On the CompTIA Linux+ XK0-005 exam, this tests your ability to apply security policies using firewalld’s rich-rule syntax rather than simpler direct service commands; a common trap is forgetting to specify the `family="ipv4"` or using `--add-service=ssh` without a source restriction, which would allow SSH from any IP. Remember the mnemonic "RASSA" — Rule, Address family, Source, Service, Accept — to recall the correct order of elements when restricting SSH to a subnet.
XK0-005 Security Practice Question
This XK0-005 practice question tests your understanding of security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A security policy requires that SSH access be allowed only from the internal management subnet 10.10.10.0/24. Which firewalld rich rule should be added?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
firewall-cmd --add-rich-rule='rule family="ipv4" source address="10.10.10.0/24" service name="ssh" accept'
Option B is correct because it uses the firewalld rich-rule syntax to explicitly define an IPv4 rule that accepts SSH traffic only from the 10.10.10.0/24 source subnet. Rich rules provide granular control over source addresses, services, and actions, which is required by the security policy. The `--add-rich-rule` option allows specifying the rule family, source address, service name, and accept action in a single, persistent rule.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
While this iptables command works, the question asks for a firewalld command.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse `--add-source` (which binds a source to a zone) with a rule filter, or they think `--add-port` combined with `--add-source` creates a source-restricted port rule, when in fact firewalld requires a rich rule to enforce source-based service restrictions.
Trap categories for this question
Command / output trap
While this iptables command works, the question asks for a firewalld command.
Detailed technical explanation
How to think about this question
Firewalld rich rules are translated into nftables (or legacy iptables) rules under the hood, but they allow atomic, human-readable definitions that can be combined with zones and services. The `rule family="ipv4"` parameter ensures the rule only applies to IPv4 traffic, avoiding unintended IPv6 matches. In a real-world scenario, if the management subnet is dual-stack, omitting the family could inadvertently allow SSH from IPv6 addresses, violating the security policy.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: firewall-cmd --add-rich-rule='rule family="ipv4" source address="10.10.10.0/24" service name="ssh" accept' — Option B is correct because it uses the firewalld rich-rule syntax to explicitly define an IPv4 rule that accepts SSH traffic only from the 10.10.10.0/24 source subnet. Rich rules provide granular control over source addresses, services, and actions, which is required by the security policy. The `--add-rich-rule` option allows specifying the rule family, source address, service name, and accept action in a single, persistent rule.
What should I do if I get this XK0-005 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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