Subject: Re: DNS SRV Clarification sought

From: Paul Vixie <[email-masked]>
Date: Sat, 06 Mar 2004 18:48:11 +0000

> ...
> RFC1035 deals with the on-the-wire encoding, while the SRV text
> above seems to be related to the usual BIND-style zone file format.
> The examples in RFC 2782 bear this out.  However, re-reading RFC 2782
> and RFC 2052, I could not determine a definitive on-the-wire encoding
> of SRV records -- this seems to be undefined.  Presumably, implementors
> have just looked at how BIND returns SRV records and gone with that.

note that if BIND is shown to be wrong, we (isc) will of course fix it.

> I tried to find an online deployment of SRV records to feed to tcpdump,
> but the closest I came was an SOA record for _tcp.microsoft.com (one of
> the authors of RFC 2782 was at Microsoft).  Neither vix.com or troll.no
> appear to have _tcp subdomains.  Does anyone actually have a deployment
> of SRV outside pseudo-DNS dynamic zones tied to DHCP servers?

vix.com has no SRV-discovered services that use tcp as their transport.
(presumably if we were a macintosh shop or a windows shop, we would?)

_kerberos._udp.vix.com/IN/SRV has some data for you, though.

> I also tried to find the IANA assignments for the Service tags, as
> referred to in RFC 2782, and couldn't locate any.  Have any actually
> been standardized?  If so, a pointer would be appreciated!

here's the problem.  SRV is experimental.  2052 was "snuck through" the
ietf process when iesg's attention was focused elsewhere, and they got
Really Angry about it when they found out.  i've apologized, since mostly
i was acting in ignorance and without malice, but it hasn't helped.  so,
in spite of the significant deployment of SRV in the community (like with
the service discovery protocols currently shipped by microsoft and apple),
SRV remains experimental.

and as long as it's only experimental, iana's charter does not cover it.

what we need to do is in two stages.  first, iesg has to tell me how i can
mend relations and achieve some kind of pardon for past SRV-related misdeeds.
(perhaps a public apologia at an iesg plenary would suffice?)  second, iana
should create a registry of service identifiers, by importing the BSD file
"/etc/services" and then periodically amending it for new standards -- and
new standards should allocate a service name not just a default port number.

i don't know how to do either of those things but that's the list, anyway.

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From: Paul Vixie <[email-masked]>
Date: Sat, 13 Mar 2004 17:15:25 +0000

> > Elevation of 2782 will give us an opportunity to clarify this.
> 
> I would like to document the "correct" usage of SRV records at DNSRD,
> so I agree that the next version of 2782 should explicitly refer to the
> correct registry document.
> 
> Now, which one is it?  port-numbers or service-names?

there isn't one.  and unless one of you writes an internet-draft which
asks iana to import /etc/services and then maintain the master copy of
it, then 2782bis will not have anything to point at.

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From: Paul Vixie <[email-masked]>
Date: Sat, 06 Mar 2004 18:48:11 +0000

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From: Paul Vixie <[email-masked]>
Date: Sat, 13 Mar 2004 17:15:25 +0000