Interpreting 'diagnose sys session filter' Output: Session Duration and State
You run 'diagnose sys session filter dport 443' and see the following output: proto=6 proto_state=01 duration=3600 expire=3599 What does this indicate?
Quick Answer
The answer is that the session has been active for 1 hour and will expire in about 1 hour. This is correct because the `duration=3600` field represents the total time in seconds since the session was established, while `expire=3599` shows the remaining seconds before the session times out, confirming a TCP session (proto=6) on port 443 in an established state (proto_state=01). On the Fortinet NSE 4 Network Security Professional exam, this output tests your ability to interpret real-time session diagnostics, a common skill for troubleshooting firewall policies and resource usage. A frequent trap is confusing `duration` with `expire`—remember that duration counts up from zero, while expire counts down to zero. For a quick memory tip, think of a stopwatch: duration is the time already run, expire is the time left on the timer.
⚠ Common exam trap
The trap here is that candidates often misinterpret `proto_state=01` as a half-open state or confuse `proto=6` with UDP, but Fortinet uses `proto_state=01` to indicate an established TCP session, not a half-open one.
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 session has been active for 1 hour and will expire in about 1 hour
The output shows `duration=3600` (seconds), meaning the session has been active for 1 hour, and `expire=3599` (seconds), meaning the session will expire in about 1 hour (3600 seconds minus 1 second already elapsed). The `proto=6` indicates TCP (protocol 6), and `proto_state=01` corresponds to an established TCP session. Therefore, option A is correct.
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 session has been active for 1 hour and will expire in about 1 hour
Why this is correct
duration=3600 seconds = 1 hour, expire=3599 seconds ≈ 1 hour. This is a normal established session.
- ✗
The session is blocked by the firewall
Why it's wrong here
The output shows an active session, not blocked.
- ✗
The session is using UDP protocol
Why it's wrong here
proto=6 indicates TCP, not UDP.
- ✗
The session is in a half-open state
Why it's wrong here
proto_state=01 typically indicates an established session, not half-open.
Go deeper
Related to this question
About these practice questions
Courseiva writes every NSE4 question from scratch — 282 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 →
Same concept, more angles
1 more way this is tested on NSE4
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You run 'diagnose sys session filter dport 443' and see the following output: proto=6 proto_state=01 duration=3600 expire=3599 What does this indicate?
hard- A.The session is using UDP protocol
- B.The session is blocked by the firewall policy
- C.The session is in SYN-SENT state
- ✓ D.The session has been established for 3600 seconds and will expire in 3599 seconds
Why D: The output shows 'duration=3600' meaning the session has been established for 3600 seconds, and 'expire=3599' meaning it will expire in 3599 seconds. 'proto=6' indicates TCP, and 'proto_state=01' indicates the session is established (TCP three-way handshake complete). Therefore, option D is correct.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE4 practice question is part of Courseiva's free Fortinet 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 NSE4 exam.