This LPIC-2 practice question tests your understanding of system 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.
A small business has a single Linux server that serves as both a file server (Samba) and a web server (Apache). The server is directly connected to the internet. Recently, there have been numerous brute-force SSH login attempts. The administrator wants to implement a simple solution to block IP addresses that have more than 5 failed SSH attempts in 10 minutes. The server runs Ubuntu 20.04. Which tool should the administrator use to achieve this with minimal configuration?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Install and configure Fail2ban to monitor /var/log/auth.log.
Option B is correct. Fail2ban is designed to monitor logs and ban IPs with excessive failures. Option A (TCP Wrappers) only controls access based on hostname/IP but does not handle dynamic banning based on failures. Option C (UFW) is a frontend to iptables but does not have built-in failure tracking. Option D (knockd) implements port knocking, which is a different concept.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Enable UFW and set default deny incoming, allow SSH from specific IPs.
Why it's wrong here
UFW does not automatically block based on failed logins.
✓
Install and configure Fail2ban to monitor /var/log/auth.log.
Why this is correct
Fail2ban can ban IPs after a configurable number of failed attempts.
Related concept
Standard ACLs match source addresses.
✗
Set up TCP wrappers with /etc/hosts.deny for SSH.
Why it's wrong here
TCP wrappers only allow/deny based on addresses, not dynamic failure count.
✗
Use port knocking to hide SSH port until a specific sequence is sent.
Why it's wrong here
Port knocking is a different security measure, not a solution for brute-force blocking.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related LPIC-2 ACL questions on filtering logic and placement.
System Security — This question tests System Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Install and configure Fail2ban to monitor /var/log/auth.log. — Option B is correct. Fail2ban is designed to monitor logs and ban IPs with excessive failures. Option A (TCP Wrappers) only controls access based on hostname/IP but does not handle dynamic banning based on failures. Option C (UFW) is a frontend to iptables but does not have built-in failure tracking. Option D (knockd) implements port knocking, which is a different concept.
What should I do if I get this LPIC-2 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related LPIC-2 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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.