Re: [BEHAVE] UDP zero checksums and v4 to v6 translators

["Rémi Denis-Courmont" <remi.denis-courmont at nokia.com>]

On Wednesday 05 August 2009 00:09:13 ext Rémi Després wrote:
> > "No harm expected"? I find that generating scary-reading false
> > positive in my
> > system logs is harmful.
>
> I don't get the point about "scary-reading false positive".

As already mentioned (several times?), some operating systems log errors when 
they receive packets with invalid checksums. The rationale is that some piece 
of hardware might be defective, or whatever.

> >> IMHO also, hosts, at their next patch release, SHOULD silently accept
> >> zero-checksum IPv6 datagrams RATHER THAN silently dropping them. No
> >> harm expected.
> >
> > That will cause silent software failures when running on a "too
> > old" system.
>
> *IPv4 compatible applications should have no problem with UDP zero-
> checksums*, or I am mistaken?

It will break silently when an *IPv6* application is run on a system that has 
not been updated to accept zero-checksum. The system will drop the packet, and 
the application will mysteriously not receive anything.

> > Silent failures are the most harmful kind of failures to me.
>
> And to me too, but I don't see any silent "failure" here.

-- 
Rémi Denis-Courmont
Nokia Devices R&D, Maemo Software, Helsinki