Re: [tsvwg] Remaining issues for draft-ietf-tsvwg-udp-options-22

["C. M. Heard" <[e-mail]>]

On Mon, Jul 3, 2023 at 4:50 PM Tom Herbert wrote:
> Considering that this is a new protocol for which there is no
> deployment and no one yet understands all the security and deployment
> ramifications, just saying "let the user decide" seems trite to me
> without providing some meaningful guidance. The discussions about the
> interactions with UDP checksum and RFC6936, and firewalls have been
> very nuanced and complicated to the extent that I wouldn't know the
> conditions that it's safe to not use a surplus checksum in my
> deployment-- I think a typical user trying to figure this out for
> their deployment would be lost.
>
> So, to simplify the things,

... in an utterly trite way ...

> I'd like to suggest this text:
>
> "By default, an implementation MUST send the OCS and an implementation
> MUST expect and validate the OCS checksum on receiving UDP packets
> with a surplus area. An implementation MAY allow the OCS to be
> configurable to both send and validate in receive. A user should fully
> consider the risks and ramifications of disabling the surplus area
> checksum, especially the risks of misinterpreting surplus area as
> containing UDP options when in fact it contains unrelated data"
>
> So basically, this is saying that if the user decides to disable the
> surplus area checksum they are doing it at their own risk. This could
> apply across use cases, so there's no need to tie this to the UDP
> checksum being zero, nor reference RFC6936. If there are concerns
> about some firewalls that want the surplus area to be checksummed,
> that can be mentioned as one thing that should be considered, but if
> user wants to disable checksum anyway they can.

There's more to it than that, which you decided to ignore.

So be it. I'm done here.

Mike Heard