RE: DNS role (RE: NATs as firewalls, cryptography, and curbing DDoS thre

--On 7. mars 2007 17:06 -0800 "Hallam-Baker, Phillip" <pbaker(_at_)verisign(_dot_)com> 
wrote:
> OK I will restate.
>
> All connection initiation should be exclusively mediated through the DNS
> and only the DNS.
OK, I'll restate too.

In my opinion, we should never introduce any function that involves the DNS 
where:
- the answer is required to be different for different requestors
- the answer has to be different at two times separated by less than 
~seconds
- a temporary failure of the resolution process is a fatal error rather 
than a delay
Since the terms "mediated" and "signalling", in the way I commonly use 
them, violates the first of these points in almost every design I'm aware 
of, I think those are lousy terms to use for any function that the DNS is 
good for.
> The reason I introduced the term signalling was precisely because setting
> up a connection today involves more than naming. Saying that the DNS
> should be the exclusive naming infrastructure is not a new position. What
> I am saying is that today session initiation involves more than the DNS
> and that this makes the IPv4/IPv6 transition more difficult than it
> should be.
If you say "the initiator of a connection can use the DNS to look up 
information about the respondent before making the connection attempt, the 
lookup process can be more complex than an A-record lookup, and that 
information can be more complex than an IP address", I can agree with you 
wholeheartedly.
If you say that "the respondent to a connection attempt can use the DNS to 
look up information about the initiator, based either on the initiator's IP 
address or on names the initiator includes in the connection attempt", I 
can agree that this is technically possible, but am worried about the 
number of devils in those details - as evidenced by the challenges of PTR 
lookup, SPF verification and so on. See also the 3rd bullet above.
But I have trouble relating those two points of agreement with the words 
"mediated" and "signalling", using any of the definitions of those words 
that I can think of offhand.
You may have a different dictionary than me. If so, please quote.

                                Harald


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