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LFCS Networking Practice Question

Exhibit

# iptables -L -n -v --line-numbers
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination
1        0     0 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
2        0     0 ACCEPT     all  --  eth0   *       0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED
3        0     0 DROP       all  --  eth0   *       0.0.0.0/0            0.0.0.0/0

Chain FORWARD (policy ACCEPT)
Chain OUTPUT (policy ACCEPT)

Refer to the exhibit. A system administrator notices that SSH connections to the server are being dropped immediately. Assuming the server's external interface is eth0, which rule is responsible for this behavior?

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

✓

Rule 3

Rule 3 drops all incoming traffic on eth0. SSH traffic is a new connection, so it does not match Rule 2 (which only accepts established/related connections). It also does not match Rule 1 (loopback). Therefore, Rule 3 drops the SSH connection.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✓

    Rule 3

    Why this is correct

    Rule 3 drops all incoming traffic on eth0, which includes new SSH connections.

  • ✗

    Both Rule 2 and Rule 3

    Why it's wrong here

    Rule 2 does not drop traffic; only Rule 3 is responsible for the drop.

  • ✗

    Rule 1

    Why it's wrong here

    Rule 1 only affects loopback interface, not eth0.

  • ✗

    Rule 2

    Why it's wrong here

    Rule 2 accepts only related/established traffic; new SSH connections are not matched.

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.