[Ecn-sane] cautionary tcp tale

[David P. Reed]

I'm pretty sure it was stated in Cerf and Kahn's paper "A Transmission Control Protocol" as published in IEEE Proceedings. I know it was in the Transmission Control Protocol Working Group email and paper documents, though I don't have a personal copy. Is it in an RFC? Probably. It's important to remember that RFC's were literally Requests for Comment in the 1970's. They weren't the entire record.

But this kind of gradual rot does creep into systems design communities. THat's why I'm wondering whether the rationale and decisions ought to be restated.

On Tuesday, August 13, 2019 5:21pm, "Rodney W. Grimes" <4bone at gndrsh.dnsmgr.net> said:

>> I'm of a mind to suggest an RFC specifically reiterating that non-endpoints MUST
>> never modify the content part of any IP datagrams, ever, with the exception of
>> the TCP and UDP extended routing header (the ports), and that solely for the
>> purpose of implementing NAT as defined in the NAT standard.
> 
> Now I think you really mean to say "modify the content part of any IP datagram
> PAYLOAD, ever" I am in agreement, the IP header itself is going to get modified a
> lot.
> 
>>
>> I think vint Cerf and I would be happy to be co-authors, maybe along with Dave
>> Clark, Noel Chiappa, and a crew of original Internet Protocol designers.
>>
>> I had thought this was a well-understood invariant, core to the design of the
>> entire Internet.
> 
> People forget history, reasons, etc, I am not even sure that it is well documented
> that IP payload should not be modified, though it may be well known information in
> some cicles, I would say that circle is of diminishing size.
> 
>>
>> Part of the reason, but certainly not all of it, was that we all intended that
>> the content within the IP datagram contents would be treated as sacrosanct, as if
>> encrypted by a key unknown to the network.
> 
> Isnt it interesting that they are actually proposing that now to protect the IP
> payload from the malicious crap that is going on, your proposal would make a rule,
> the encryption solution would silently enforce that rule without question.
> 
>> We could not require end-to-end encryption because of ITAR rules at the time. But
>> it is absolutely clear that NOTHING in the network transport system was expected
>> to attempt to understand or to modify those bits until they reached the
>> destination, unchanged.
>>
>> It wasn't just a "good idea", it was a design requirement.
> 
> Perhaps a poorly documented one?  Can you site any RFC verbage that addresses
> this?
> 
> I would support any effort to codify this in a I-D.
> 
>> On Tuesday, August 13, 2019 12:39pm, "Michael Richardson" <mcr at sandelman.ca>
>> said:
>>
>> > Thanks.
>> > Also a good story as to why middle boxes should stay away from mangling
>> > packets without an audit trail.
>> >
>>
> 
> --
> Rod Grimes                                                 rgrimes at freebsd.org
>