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Wireshark-users: [Wireshark-users] Wireshark Capture Filter Using Offset

From: "George E Burns" <geburns@xxxxxxxxxxx>
Date: Mon, 19 Jul 2010 17:27:09 -0400
Hello,

I have a question regarding "capture" filters.  Specifically, I need to write a low level filter that will capture dynamic DNS update packets containing the opcode value of 0x05.  I know what the offset value is (0x2C and 0x2D) in the payload, but apparently I am missing something when trying to understand the correct "tcp dump" syntax to use as part of the capture filter in Wireshark.  

Capture Filter:         udp[2c] == 28 and udp[2d] == 00


Any input is greatly appreciated!


Thanks,

geburns

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