mediumMultiple ChoiceObjective-mapped
300-410 Practice Question: Given the following configuration: ``` interface…
Given the following configuration: ```
interface GigabitEthernet0/2 ip access-group FILTER_SSH in
!
ip access-list extended FILTER_SSH permit tcp any host 192.168.1.10 eq 22 permit udp any host 192.168.1.10 eq 22
``` What is the issue with this ACL?
⚠ Common exam trap
Cisco often tests the misconception that SSH uses both TCP and UDP, or that permitting UDP port 22 is harmless, when in fact only TCP port 22 is valid for SSH.
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 ACL permits UDP port 22, which is not used by SSH; this could allow unwanted UDP traffic.
The ACL permits both TCP and UDP traffic to destination port 22. SSH uses only TCP port 22; UDP port 22 is not used by SSH. The second permit statement allows any UDP traffic to port 22, which could be unwanted (e.g., UDP-based attacks or non-SSH services). This is the issue.
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 ACL permits UDP port 22, which is not used by SSH; this could allow unwanted UDP traffic.
Why this is correct
Correct. SSH uses TCP, so the UDP permit is unnecessary and potentially risky.
- ✗
The ACL is missing a deny statement at the end to block other traffic.
Why it's wrong here
Incorrect. There is an implicit deny at the end of all ACLs; it is not required to be explicit.
- ✗
The ACL should use the 'established' keyword to allow return traffic.
Why it's wrong here
Incorrect. The 'established' keyword is used for TCP sessions, but the ACL permits inbound SSH to a specific host, which is correct for inbound connections.
- ✗
The ACL should be applied outbound instead of inbound.
Why it's wrong here
Incorrect. The direction depends on the desired filtering; inbound is appropriate for filtering traffic coming into the interface.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 1,966 original 300-410 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 practice question is part of Courseiva's free Cisco 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 300-410 exam.