Question 79 of 144
SK0-005 server-administration Practice Question
Network Topology
Refer to the exhibit. A server administrator configured iptables rules on a Linux server. Immediately afterward, they are unable to connect to the server via SSH. The output of 'iptables -L INPUT -n' is shown. What is the most likely cause of the connectivity issue?
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
✓
The DROP rule for port 22 appears before the ACCEPT rule, causing all SSH packets to be dropped.
iptables processes rules in order. The DROP rule for destination port 22 appears before the ACCEPT rule, so all incoming SSH packets are dropped before the ACCEPT rule can permit new connections.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The last DROP rule blocks all traffic, including established SSH sessions.
Why it's wrong here
The last DROP rule blocks traffic, but the earlier ACCEPT for RELATED,ESTABLISHED allows return packets of existing connections, so this does not explain new SSH failure.
- ✓
The DROP rule for port 22 appears before the ACCEPT rule, causing all SSH packets to be dropped.
Why this is correct
Correct. With the DROP preceding the ACCEPT, every SSH packet matches the DROP target first.
- ✗
The default INPUT policy is set to ACCEPT, allowing all traffic.
Why it's wrong here
A default ACCEPT policy does not override an earlier DROP rule; the DROP for SSH still takes effect.
- ✗
The ACCEPT rule for port 22 is missing the ESTABLISHED state, preventing return traffic.
Why it's wrong here
The ACCEPT rule uses state NEW, which is fine; the RELATED,ESTABLISHED rule permits return traffic. The problem is the order.
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Last reviewed: Jul 26, 2026
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