Wireshark-users: Re: [Wireshark-users] Checksum Display Filters
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From: Jaap Keuter <jaap.keuter@xxxxxxxxx>
Date: Sun, 11 Feb 2007 22:32:10 +0100 (CET)
Hi,

Not for UDP, there the checksum can be omitted.

Thanx,
Jaap

On Sun, 11 Feb 2007, Keith French wrote:

> In the IP, TCP or UDP headers is the "Checksum" field, which has two parts to it. For the IP checksum this is:-
>
> Header checksum: 0xbbd5 [correct]
>         [Good: True]
>         [Bad : False]
>
> with similar for the TCP and UDP checksums.
>
> Is there any difference from a logical point of view when using a display filter to find packets with bad IP checksums between these two expressions:-
>
> ip.checksum_bad == 1
>
> or
>
> ip.checksum_good == 0
>
> As a checksum can only be correct or bad, surely both of these filters are the same?
>