Subject: Re: Last Call: IPv6 Node Information Queries to Proposed Standard

From: [email-masked]
Date: Tue, 05 Sep 2000 18:17:52 +0900

>My biggest concern about this proposal is that it doesn't specify the
>purposes for which this service can be used.  To put it another way,
>what services can rely on this information, and what services are 
>allowed to break if the result from the ICMPv6 query doesn't correspond 
>to what can be obtained from DNS (or to what applications running on 
>that host believe)?  

	at IETF48 zeroconf WG and dnsext WG, I heard some comment on making
	distinction between full qualified domain name (which is on the DNS
	database), and hostname (which is configured onto each of the host,
	and do not necessarily the same as FQDN).  Not sure if it has wide
	concensus, but it made some sense to me.
	- we look up FQDN through DNS database
	- we look up hostname through /etc/hosts
		(i'm not sure if it is really correct)
	- gethostname(3) returns hostname, not FQDN

	it is kind of confusing, but this gave me a way to understand the
	current situation.  if we are okay with the distinction,
	we may be able to state the following:
	- if we are to lookup some name via ICMPv6 name lookup, it would
	  be hostname, not FQDN.
	we need to update name-lookup draft again, though.

	of course, the above distinction could be very wrong.  but then,
	how should we understand the current situation with gethostname(3)?

itojun
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From: Keith Moore <[email-masked]>
Date: Tue, 05 Sep 2000 06:54:46 -0400

>         - gethostname(3) returns hostname, not FQDN

my experience is more like:
	- hostname is set as part of system configuration (during boot)
	(you can't look it up in /etc/hosts because you need to know 
	what to look for)
	- hostname can either be an alias (usually just a label) or an FQDN
	- you can sometimes look up hostname in local DNS and get back an FQDN
	- the mapping from hostname to FQDN might or might not involve
	adding a domain suffix to the hostname. 
	
>         we need to update name-lookup draft again, though.

okay, but this still doesn't answer the question.  what is the purpose of
this service, and what things are allowed to depend on it?

Keith

---

From: [email-masked]
Date: Tue, 05 Sep 2000 23:29:53 +0900

>this service, and what things are allowed to depend on it?

	under zeroconf situation, you may want to lookup:
	- an address from a hostname, using ICMPv6 name lookup (query type =
	  node addresses) toward ff02::1 (or NI group address)
	- an address to a hostname, using ICMPv6 name lookup (query type = 
	  DNS name/hostname) toward the address
	the message type can be used just like mDNS proposals (see
	draft-aboba-dnsext-mdns-01.txt).

	also, it has been really useful for debugging.

	not 100% sure if the use of icmp6 is a good idea or not.  also, as you
	noted, icmp6 may seem like a layer violation.  if you have better
	suggestion, please let me know.

	(NOTE: I understand the security issues by giving away more
	information to bad guys)

itojun