The answer is that incoming SSH connections on eth0 are allowed if they are new. This is correct because the iptables rule on the INPUT chain explicitly matches TCP packets destined for port 22 with the state NEW, which corresponds to the initial SYN packet of a connection attempt. Since the default policy for the INPUT chain is ACCEPT, the rule serves as an explicit permit for new SSH sessions rather than a necessary one, but it ensures that only fresh connection requests are accepted without interference from state-matching rules. On the LPIC-2 exam, this scenario tests your understanding of connection tracking and stateful filtering in iptables, often appearing in questions that ask you to interpret rule output and distinguish between NEW, ESTABLISHED, and RELATED states. A common trap is assuming a DROP default policy exists when it does not, so always check the chain policy first. Memory tip: “NEW on 22 means the SYN is let through.”
LPIC-2 System Security Practice Question
This LPIC-2 practice question tests your understanding of system 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.
Network Topology
Based on the iptables output, what is the expected behavior for incoming SSH connections on eth0?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SSH connections from any source to port 22 on eth0 are allowed if they are new.
The iptables output shows a rule on the INPUT chain for eth0 that accepts TCP packets destined for port 22 (SSH) with the state NEW. This means that any incoming SSH connection attempt (SYN packet) that is not part of an existing connection is explicitly allowed. The default policy for the INPUT chain is ACCEPT (not shown as DROP), so even without this rule, SSH would be allowed, but the rule ensures it is explicitly permitted for new connections.
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.
✗
SSH connections are only allowed if they are part of an established connection.
Why it's wrong here
The rule matches state NEW, not ESTABLISHED.
✓
SSH connections from any source to port 22 on eth0 are allowed if they are new.
Read the scenario before looking for a memorised answer.
✗
SSH connections are dropped because the default policy is DROP.
Why it's wrong here
The rule overrides the default policy for matching packets.
✗
SSH connections are only allowed from the loopback interface.
Why it's wrong here
The rule accepts on eth0, not lo.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume the default policy is DROP (a common security practice) and overlook the explicit ACCEPT rule for NEW SSH connections, or they may confuse the NEW state with ESTABLISHED, thinking that only existing connections are allowed.
Detailed technical explanation
How to think about this question
In iptables, connection tracking states (NEW, ESTABLISHED, RELATED, INVALID) are managed by the conntrack module. The NEW state matches the first packet of a connection (typically a SYN packet in TCP). For SSH, this rule ensures that the initial handshake is permitted, while subsequent packets are matched by an ESTABLISHED rule (often a separate rule like '-m state --state ESTABLISHED,RELATED -j ACCEPT'). In real-world scenarios, administrators often place the ESTABLISHED rule before the NEW rule to optimize performance and ensure return traffic is allowed.
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 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
System Security — This question tests System Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: SSH connections from any source to port 22 on eth0 are allowed if they are new. — The iptables output shows a rule on the INPUT chain for eth0 that accepts TCP packets destined for port 22 (SSH) with the state NEW. This means that any incoming SSH connection attempt (SYN packet) that is not part of an existing connection is explicitly allowed. The default policy for the INPUT chain is ACCEPT (not shown as DROP), so even without this rule, SSH would be allowed, but the rule ensures it is explicitly permitted for new connections.
What should I do if I get this LPIC-2 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.