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DNS Checksum

asked 2018-10-20 17:48:35 +0000

Yudistryan Izhar gravatar image

Hi I'm still learning how to use wireshark properly. Can you help me explain how to calculate the DNS checksum? Is it the same way we calculate UDP checksum?

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What field are you referring to exactly? What display filter matches this field (you can find it in the lower left corner of the Wireshark window)?

Jaap gravatar imageJaap ( 2018-10-21 08:58:48 +0000 )edit

I use dns filter. In the UDP line, there is a checksum. I want to verify the checksum but I can't figure it out how

Yudistryan Izhar gravatar imageYudistryan Izhar ( 2018-10-21 09:01:47 +0000 )edit

In the UDP line, there is a checksum

That's the UDP checksum, not the DNS checksum. DNS is transported over UDP (and sometimes over TCP); the UDP checksum in a DNS-over-UDP packet is part of UDP, not DNS.

Guy Harris gravatar imageGuy Harris ( 2018-10-21 21:14:48 +0000 )edit

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answered 2018-10-21 18:09:29 +0000

Jaap gravatar image

The UDP checksum is "Checksum is the 16-bit one's complement of the one's complement sum of a pseudo header of information from the IP header, the UDP header, and the data, padded with zero octets at the end (if necessary) to make a multiple of two octets.", as per RFC 768. See also the TCP/IP Guide, or wikipedia.

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Asked: 2018-10-20 17:48:35 +0000

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Last updated: Oct 21 '18