Re: UDP zero checksums and v4 to v6 translators

[Christopher Morrow <christopher.morrow at gmail.com>]

On Tue, Jul 28, 2009 at 4:53 AM, Francis
Dupont<Francis.Dupont at fdupont.fr> wrote:
>  In your previous mail you wrote:
>
>   On Tue, Jul 28, 2009 at 3:29 AM, Francis
>   Dupont<Francis.Dupont at fdupont.fr> wrote:
>   >  In your previous mail you wrote:
>   >
>   >   Thoughts?
>   >
>   > => I am strongly against changing all IPv6 implementations.
>   > IMHO the simplest solution is to drop UDP packets with zero checksums
>   > (as far as I know all IPv4 implementations use non-zero checksums
>   > per default and some UDP applications, for instance DNS, work far
>   > better with non-zero checksums. BTW it is an easy condition to check
>   > in firewalls).
>
>   Out of curiosity, what's the signal back to the sender that his/her
>   packet was dropped??
>
> => none but if you really want something an unreachable / admin forbidden
> seems not so bad.

ok. my sole point really was 'discard' is not acceptable. if you toss
away a packet you ought to tell someone you did that.

>   NFS (in some implementations) doesn't checksum UDP packets,
>
> => NFS over UDP throught a translator is already a bad idea.

it's not that the user chooses this, they just get pushed across this
without their knowledge. windows-sharing over the internet isn't
smart, but a shockingly large number of people do it. Same for ms-sql
server...

-chris