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Asterix Dissector not Triggering on data generated by ScanViewer

asked 2023-06-07 16:15:06 +0000

GeorgeZ gravatar image

Hello everyone!

I have a simulator called ScanViewer which generates Asterix CAT240 data for me. Unfortunately, the data packets aren't triggering the Asterix dissector so it's hard for me to analyse the data.

I manually checked a packet and it wasn't much different from a packet found within a stream I downloaded from the web. The packets are registered with a faulty checksum value, so I'm wondering if that could be the source of the issue.

Did anyone else come across this issue?

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Can you share a capture file on a public file share and update the question with a link to it.

Chuckc gravatar imageChuckc ( 2023-06-07 16:57:50 +0000 )edit

What @Chuckc said. Also, does this traffic flow on UDP port 8600? or did you change the preference for that? Do the packets adhere to the format: 1 octet Category, 2 octets Length, followed by n records?

Jaap gravatar imageJaap ( 2023-06-07 17:28:28 +0000 )edit

Morning! Here's is a set of sample packets: Google Drive link Please tell me if you spot something in the way that the packets are getting sent.

GeorgeZ gravatar imageGeorgeZ ( 2023-06-08 09:45:36 +0000 )edit

Can you make the file public?

Chuckc gravatar imageChuckc ( 2023-06-08 09:51:16 +0000 )edit

So sorry! Try now

GeorgeZ gravatar imageGeorgeZ ( 2023-06-08 09:58:26 +0000 )edit

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answered 2023-06-08 10:36:14 +0000

Chuckc gravatar image

updated 2023-06-08 13:00:49 +0000

What @Jaap said. Add 5800 and 2563 to the Asterix UDP port(s):

UDP port(s): 8600,5800,2563

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Thank you both of you! What is the reason behind the solution? Why would the port affect dissection?

GeorgeZ gravatar imageGeorgeZ ( 2023-06-08 12:53:55 +0000 )edit

To let the UDP dissector know that if it sees traffic on one of the Asterix ports, call that dissector.

View -> Internals -> Dissector Tables
Integer Tables -> UDP port

(See the screen shot in answer above)

Chuckc gravatar imageChuckc ( 2023-06-08 13:00:16 +0000 )edit

I see now, thank you!

GeorgeZ gravatar imageGeorgeZ ( 2023-06-08 13:03:46 +0000 )edit

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Asked: 2023-06-07 16:15:06 +0000

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Last updated: Jun 08