LPIC-2 Advanced Networking Configuration Practice Question
A system administrator wants to allow incoming SSH connections from only the 192.168.1.0/24 network on a Linux server. Which iptables rule accomplishes this?
⚠ Common exam trap
Candidates often confuse the INPUT and FORWARD chains, or swapping the source (-s) and destination (-d) flags, leading candidates to choose a rule that either filters the wrong direction or applies to the wrong packet flow.
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
✓
iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT
It appends a rule to the INPUT chain that matches TCP traffic destined for port 22 (SSH) from source IP range 192.168.1.0/24 and accepts it. This restricts incoming SSH connections to only the specified network, which is the intended behavior.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
iptables -A INPUT -p tcp --dport 22 -d 192.168.1.0/24 -j ACCEPT
Why it's wrong here
The -d flag specifies destination, not source; it would allow traffic destined to that network, not from it.
- ✗
iptables -A INPUT -p udp --dport 22 -s 192.168.1.0/24 -j ACCEPT
Why it's wrong here
SSH uses TCP, not UDP.
- ✗
iptables -A FORWARD -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT
Why it's wrong here
This applies to the FORWARD chain, which is for forwarded packets, not packets destined to the local host.
- ✓
iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT
Why this is correct
This rule correctly matches incoming SSH traffic from the specified source net.
Visual reference
Go deeper
Related to this question
About these practice questions
Courseiva writes every LPIC-2 question from scratch — 507 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.