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display filter is green, but capture shows up blank

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challenge.101 3.4 question How many frames have the TCP SYN bit set to 1? frame matches"(?!)set-cookie" is in the display filter when I hit enter it the sample capture comes in blank. How do I get the capture to display ?

2Tonz's avatar
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2Tonz
asked 2022-05-27 14:07:08 +0000
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Can you add a link to the website where the challenge question comes from?

grahamb's avatar grahamb (2022-05-28 11:08:00 +0000) edit
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When a filter is 'green', it means that there is no syntax error in the filter itself. The result can still be empty.

Only if you filter for something that is actually present in the capture, the list won't be 'blank'.

TCP SYN bit set to 1: tcp.flags.syn==1

frame matches"(?!)set-cookie": did you mean contains? "(?!)" = Negative Lookahead, why?

André's avatar
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André
answered 2022-05-28 21:38:28 +0000
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If filtering from challenge 3-1 q&a why would the capture be blank ?

2Tonz's avatar 2Tonz (2022-08-10 16:18:31 +0000) edit

If filtering from challenge 3-1 q&a

As asked before: where does the challenge question comes from?

why would the capture be blank ?

Only if you filter for something that is actually present in the capture, the list won't be 'blank'.

André's avatar André (2022-08-10 19:50:47 +0000) edit

What you mean where the question comes from. The question is How many frames comes to and from 80.78.246.209. This is just a simple ip.addr==80.78.246.209 I apply the filter and the capture comes back blank.

2Tonz's avatar 2Tonz (2022-08-10 22:24:38 +0000) edit

What you mean where the question comes from.

To quote grahamb comment on May 28th: "Can you add a link to the website where the challenge question comes from?"

You cannot assume we know about all challenges / trainings / courses / books out there that contain the word "Wireshark" in the title... So if you want support on a network capture you'll have to provide that here by sharing a link.

So you used ip.addr==80.78.246.209 as a display filter, then the answer is still valid:

  • It is 'green' because the syntax is correct.
  • When no frame in your network capture contains this IP-address, zero frames will be shown in the display when applied.
    Use Statistics / Endpoints to list what is present.
André's avatar André (2022-08-11 20:10:31 +0000) edit
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