Subject: I-D ACTION:draft-song-dnsext-nai-support-00.txt

From: [email-masked]
Date: Wed, 09 Jan 2002 16:02:11 -0500

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title		: DNS RR type for NAI
	Author(s)	: J. Song et al.
	Filename	: draft-song-dnsext-nai-support-00.txt
	Pages		: 6
	Date		: 08-Jan-02
	
This document proposes the use of the new DNS RR type 'NAI' to 
specify the most current location of the user(Host IP address).

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From: Simon Josefsson <[email-masked]>
Date: Thu, 10 Jan 2002 00:02:18 +0100

This draft looks useful, I have only one minor comment.  In section 3
which describes the name syntax, have you considered using the SOA
emailaddress -> domainname translation instead?  That is, your example
in section 4 would look like:

junhyuk.samsung.skt.co.kr.  86400  IN   NAI  165.213.221.4

instead of

junhyuk@.samsung.skt.co.kr.  86400  IN   NAI  165.213.221.4

Perhaps the TTL in the example should be smaller as well, given your
TTL discussion.

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---

From: [email-masked]
Date: Thu, 10 Jan 2002 14:37:35 +1100

There are some obvious flaws in this to start with.

	1. the world in no longer just IPv4.
	2. there is no way to say that the user is just off-net.
	3. there is already well established ways to map these
	   sorts of addresses into domain names.  You need to
	   justify why there should be another method used.

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: [email-masked]

---

From: Derek Atkins <[email-masked]>
Date: 09 Jan 2002 22:52:23 -0500

Simon,

Based on your suggestion, how would you cope with a sitation where a
site has an alias (cname) that happens to match a username?  For
example, assume you have a user "[email-masked]" (not a hard
assumption ;) and you already have the following host (cname) record:

warlord.mit.edu.  IN  CNAME  some-computer.mit.edu.

How are you supposed to add in:

warlord.mit.edu.  IN  NAI  ....

Keep in mind that CNAMEs are not allowed to co-exist with other RR
types at a node.  Similar problem if a username matches a subdomain
(because the data would want to live in the child zone).

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       [email-masked]                        PGP key available

---

From: Ben Clifford <[email-masked]>
Date: Wed, 9 Jan 2002 20:59:23 -0800 (PST)

> specify the most current location of the user(Host IP address).

It seems that what you mean "user" means something along the lines of
"mobile host, belonging to a person" rather than actually meaning a
"person".

Forgive me if I am overlooking something, but what is wrong with using the
A RR type for this purpose (used, as you suggest in the draft, with short
TTL and with the label formatted as you suggest)

For example, junhyuk@.samsung.skt.co.kr.  30  IN   A  165.213.221.4

Is there some extra implied meaning, for example, that NAI hosts should be
able to keep TCP connections open, even though the IP address has changed?

-- 
Ben Clifford [email-masked]
http://www.hawaga.org.uk/ben/ GPG: 30F06950 - signed/encrypted mail
encouraged
Job Required - Will do most things unix or IP for money.

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---

From: Ben Clifford <[email-masked]>
Date: Wed, 9 Jan 2002 21:05:04 -0800 (PST)

> assumption ;) and you already have the following host (cname) record:

Perhaps you shouldn't use the root DNS name as the realm name?

For example,
warlord.student-realm.mit.edu
or
warlord.faculty-realm.mit.edu

If you are putting in symbols to separate out different kinds of object, I
would think that the standard way to do it (x.subdomain.y.gov) would be
the better way?

-- 
Ben Clifford     [email-masked]
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---

From: Derek Atkins <[email-masked]>
Date: 10 Jan 2002 00:33:56 -0500

> warlord.faculty-realm.mit.edu

You are implying a separation where one does not exist.  There _is_
no "[email-masked]".

My point was that "warlord@.mit.edu." would work but removing the
trailing '@' causes problems.  Obviously there are other naming
tricks we could do (I believe you are suggesting that, but I disagree
with your example suggestion).  I think a better suggestion would
be:
	warlord._user.mit.edu.

> would think that the standard way to do it (x.subdomain.y.gov) would be

No, because you have the same potential problem... If you ever have a
user name that matches a subdomain you get into trouble.  The only way
to do it is to create a special subdomain (ala SRV records) that uses
a special name which you can pretty much guarantee will never exist.

Never mind the fact that I'm not convinced the NAI record is something
that needs to happen.  We already have IMPP; why do we need DNS to
give the same location information?  IMPP is already designed to have
users register their precense (location) information.  I'm not
convinced that DNS can provide the level of dynamic or duplicate
information that IMPP can provide.

-derek

---

From: Simon Josefsson <[email-masked]>
Date: Thu, 10 Jan 2002 12:42:02 +0100

I would add the NAI RR at some-computer.mit.edu instead.

Before we get into the case where the CNAME points at a machine in a
different zone (is that really a likely scenario?) or another user
named "some-computer" (ditto), I'd agree that using
user._nai.example.org might solve this more cleanly.  (not _user)

As for IPv6, Mobile IPv4 is not compatible with Mobile IPv6 so they
need separate mechanisms, or a RR format that can encode both IPv4 and
IPv6 addresses.