hardMultiple ChoiceObjective-mapped
ISC2 CC Practice Question: A system administrator runs `iptables -L INPUT`…
Exhibit
Refer to the exhibit. ``` Chain INPUT (policy ACCEPT) target prot opt source destination DROP tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 state NEW ```
A system administrator runs `iptables -L INPUT` and sees this rule. What is the immediate effect on the system?
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
✓
New SSH connections are blocked, but current SSH sessions remain active.
The rule drops all new TCP connections to port 22 (SSH) from any source, preventing new SSH 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.
- ✗
All SSH traffic is blocked, including established sessions.
Why it's wrong here
The rule only drops NEW state, so established connections are still allowed.
- ✓
New SSH connections are blocked, but current SSH sessions remain active.
Why this is correct
The rule drops NEW packets for SSH, so new connections are blocked; established connections are unaffected.
- ✗
The rule has no effect because the policy is ACCEPT.
Why it's wrong here
The rule explicitly drops, overriding the default policy for matching traffic.
- ✗
All outbound SSH connections are blocked.
Why it's wrong here
This is the INPUT chain, so it affects incoming traffic, not outbound.
Visual reference
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Related to this question
Learn chapter
Incident Response and Management
Key term
SSH
SSH (Secure Shell) is a cryptographic network protocol that provides secure, encrypted communication and remote administration between two devices over an unsecured network.
Key term
iptables
iptables is a command-line firewall utility in Linux that uses rules to allow or block network traffic based on packet attributes like source IP, destination port, or protocol.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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