Ethereal-users: Re: [ethereal-users] UDP/ICMP Checksums

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From: Guy Harris <gharris@xxxxxxxxxxxx>
Date: Thu, 14 Sep 2000 11:18:57 -0700
On Thu, Sep 14, 2000 at 06:24:26PM +0200, Markus Schaber wrote:
> Now I noticed that it correctly shows the checksum-headers for IP, UDP
> and ICMP, but it seems that it only checks the IP checksum for
> correctnes, and doesn't check the correctnes of the UDP and ICMP
> checksum (I couldn't test TCP so far).
> 
> Now I would like to know whether I got this correct,

You are correct that the only checksum it checks is the IP header
checksum.

> and how easy it is to add this.

I have code to do it, but it's not finished; I need to make it *not*
check the checksum if the IP datagram containing the ICMP datagram/UDP
datagram/TCP segment is fragmented (we don't yet reassemble fragmented
IP datagrams, so we can't yet compute the checksum on the payload of a
fragmented IP datagram).