draft-ietf-ipngwg-icmp-name-lookups-07.txt   draft-ietf-ipngwg-icmp-name-lookups-08.txt 
IPng Working Group Matt Crawford IPng Working Group Matt Crawford
Internet Draft Fermilab Internet Draft Fermilab
August 28, 2000 July 20, 2001
IPv6 Node Information Queries IPv6 Node Information Queries
<draft-ietf-ipngwg-icmp-name-lookups-07.txt> <draft-ietf-ipngwg-icmp-name-lookups-08.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working all provisions of Section 10 of RFC2026. Internet-Drafts are
documents of the Internet Engineering Task Force (IETF), its areas, working documents of the Internet Engineering Task Force (IETF), its
and its working groups. Note that other groups may also distribute areas, and its working groups. Note that other groups may also
working documents as Internet-Drafts. distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet- Drafts as at any time. It is inappropriate to use Internet- Drafts as
reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
To view the list Internet-Draft Shadow Directories, see To view the list Internet-Draft Shadow Directories, see
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
This document describes a protocol for asking an IPv6 node to supply This document describes a protocol for asking an IPv6 node to supply
certain network information, such as its fully-qualified domain certain network information, such as its hostname or fully-qualified
name. IPv6 implementation experience has shown that direct queries domain name. IPv6 implementation experience has shown that direct
for a DNS name are useful, and a direct query mechanism for other queries for a hostname are useful, and a direct query mechanism for
information has been requested. other information has been found useful in serverless environments
and for debugging.
1. Terminology 1. Introduction
This docment specifies a mechanism for discovering information about
names and addresses. (The mechanism is extensible to deal with
other information). In the global internet, the Domain Name System
[1034, 1035] is the authoritative source of such information and
this specifcation is not intended to supplant or supersede it. And
in fact, in a well-supported network the names and addresses dealt
with by this mechanism will be the same ones, and with the same
relationships, as those listed in the DNS.
This new Node Information protocol does provide facilities which are
not found in the DNS - for example discovering relationships between
addresses without reference to names. And the functions that do
overlap with the DNS may be useful in serverless environments, for
debugging, or in regard to link-local and site-local addresses
[2373] which often will not be listed in the DNS.
2. Terminology
A "Node Information (or NI) Query" message is sent by a "Querier" A "Node Information (or NI) Query" message is sent by a "Querier"
node to a "Responder" node in an ICMPv6 packet addressed to the node to a "Responder" node in an ICMPv6 packet addressed to the
"Queried Address." The Query concerns a "Subject Address" which may "Queried Address." The Query concerns a "Subject Address" which may
differ from the Queried Address, or a "Subject Name". The Responder differ from the Queried Address, or a "Subject Name". The Responder
sends a "Node Information Reply" to the Querier, containing sends a "Node Information Reply" to the Querier, containing
information associated with the node at the Queries address. A node information associated with the node at the Queries address. A node
receiving a NI Query will be termed a Responder even if it does not receiving a NI Query will be termed a Responder even if it does not
send a Reply. send a Reply.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [2119]. document are to be interpreted as described in [2119].
Packet fields marked "unused" must be zero on transmission and, Packet fields marked "unused" must be zero on transmission and,
aside from inclusion in checksums or message integrity checks, aside from inclusion in checksums or message integrity checks,
ignored on reception. ignored on reception.
2. Node Information Messages 3. Node Information Messages
Two types of Node Information messages, the NI Query and the NI Two types of Node Information messages, the NI Query and the NI
Reply, are carried in ICMPv6 [2463] packets. They have the same Reply, are carried in ICMPv6 [2463] packets. They have the same
format. format.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 2, line 42 skipping to change at page 3, line 14
Fields: Fields:
Type 139 - NI Query. Type 139 - NI Query.
140 - NI Reply. 140 - NI Reply.
Code For NI Query: Code For NI Query:
0 Indicates that the Data field contains an IPv6 0 Indicates that the Data field contains an IPv6
address which is the Subject of this Query. address which is the Subject of this Query.
1 Indicates that the Data field contains a domain name 1 Indicates that the Data field contains a name which
which is the Subject of this Query, or is empty, as is the Subject of this Query, or is empty, as in the
in the case of a NOOP or Supported Qtypes query. case of a NOOP or Supported Qtypes query.
2 Indicates that the Data field contains an IPv4 2 Indicates that the Data field contains an IPv4
address which is the Subject of this Query. address which is the Subject of this Query.
For NI Reply: For NI Reply:
0 Indicates a successful reply. The Reply Data field 0 Indicates a successful reply. The Reply Data field
may or may not be empty. may or may not be empty.
1 Indicates that the Responder refuses to supply the 1 Indicates that the Responder refuses to supply the
answer. The Reply Data field will be empty. answer. The Reply Data field will be empty.
2 Indicates that the Qtype of the Query is unknown to 2 Indicates that the Qtype of the Query is unknown to
the Responder. The Reply Data field will be empty. the Responder. The Reply Data field will be empty.
Checksum The ICMPv6 checksum. Checksum The ICMPv6 checksum.
Qtype A 16-bit field which designates the type if information Qtype A 16-bit field which designates the type of information
requested in a Query or supplied in a Reply. Its value requested in a Query or supplied in a Reply. Its value
in a Reply is always copied from the corresponding Query in a Reply is always copied from the corresponding Query
by the Responder. Five values of Qtype are specified in by the Responder. Five values of Qtype are specified in
this document. this document.
Flags Qtype-specific flags which may be defined for certain Flags Qtype-specific flags which may be defined for certain
Query types and their Replies. Flags not defined for a Query types and their Replies. Flags not defined for a
given Qtype must be zero on transmission and ignored on given Qtype must be zero on transmission and ignored on
reception, and must not be copied from a Query to a reception, and must not be copied from a Query to a
Reply unless so specified in the definition of the Reply unless so specified in the definition of the
skipping to change at page 3, line 44 skipping to change at page 4, line 14
Data In a Query, the Subject Address or Name. In a Reply, Data In a Query, the Subject Address or Name. In a Reply,
Qtype-specific data present only when the ICMPv6 Code Qtype-specific data present only when the ICMPv6 Code
field is zero. The length of the Data may be inferred field is zero. The length of the Data may be inferred
from the IPv6 header's Payload Length field [2460], the from the IPv6 header's Payload Length field [2460], the
length of the fixed portion of the NI packet and the length of the fixed portion of the NI packet and the
lengths of the ICMPv6 header and intervening extension lengths of the ICMPv6 header and intervening extension
headers. headers.
Note that the type of information present in the Data field of a Note that the type of information present in the Data field of a
Query is inferred from the ICMP Code, while the type of information, Query is declared by the ICMP Code, while the type of information,
if any, in the Data field of a Reply is inferred from the Qtype. if any, in the Data field of a Reply is determined by the Qtype.
When the Subject of a Query is a name, the name MUST be in DNS wire When the Subject of a Query is a name, the name MUST be in DNS wire
format [1035]. The name may be either a fully-qualified domain format [1035]. The name may be either a fully-qualified domain
name, including the terminating zero-length label, or a single DNS name, including the terminating zero-length label, or a single DNS
label followed by two zero-length labels. Since a Query contains at label followed by two zero-length labels. Since a Query contains at
most one DNS name, DNS compression will not be used. most one name, DNS name compression MUST NOT be used.
3. Message Processing 4. Message Processing
The Querier constructs an ICMP NI Query and sends it to the address The Querier constructs an ICMP NI Query and sends it to the address
from which information is wanted. When the Subject of the Query is from which information is wanted. When the Subject of the Query is
an IPv6 address, that address will normally be used as the IPv6 an IPv6 address, that address will normally be used as the IPv6
destination address of the Query, but need not be if the Querier has destination address of the Query, but need not be if the Querier has
useful a priori information about the addresses of the target node. useful a priori information about the addresses of the target node.
An NI Query may also be sent to a multicast address of link-local An NI Query may also be sent to a multicast address of link-local
scope [2373]. scope [2373].
When the Subject is a domain name, either fully-qualified or When the Subject is a name, either fully-qualified or single-
single-component, and the Querier does not have a unicast address component, and the Querier does not have a unicast address for the
for the target node, the query MUST be sent to a link-scope target node, the query MUST be sent to a link-scope multicast
multicast address formed in the following way. The Subject Name is address formed in the following way. The Subject Name is converted
converted to canonical form, as defined by DNS Security [2535], to the canonical form defined by DNS Security [2535], which is
which is uncompressed with all alphabetic characters in lower case. uncompressed with all alphabetic characters in lower case. (If
(If additional DNS label types for host names are defined, the rules additional DNS label types for host names are created, the rules for
for canonicalizing those labels will be found in the defining canonicalizing those labels will be found in their defining
specification.) Compute the MD5 hash [1321] of the first label of specification.) Compute the MD5 hash [1321] of the first label of
the Subject Name -- the portion beginning with the first one-octet the Subject Name -- the portion beginning with the first one-octet
length field and up to, but excluding, any subsequent length field. length field and up to, but excluding, any subsequent length field.
Append the first 32 bits of that 128-bit hash to the prefix Append the first 32 bits of that 128-bit hash to the prefix
FF02:0:0:0:0:2::/96. The resulting multicast address will be termed FF02:0:0:0:0:2::/96. The resulting multicast address will be termed
the "NI Group Address" for the name. the "NI Group Address" for the name.
The Nonce should be a random or good pseudo-random value to foil The Nonce should be a random or good pseudo-random value to foil
spoofed replies. An implementation which allows multiple spoofed replies. An implementation which allows multiple
independent processes to send NI queries MAY use the Nonce value to independent processes to send NI queries MAY use the Nonce value to
skipping to change at page 5, line 15 skipping to change at page 5, line 34
matches the Subject. All name matching is done in a case- matches the Subject. All name matching is done in a case-
independent manner consistent with DNSSEC name canonicalization independent manner consistent with DNSSEC name canonicalization
[2535]. [2535].
Next, if Qtype is unknown to the Responder, it must return a NI Next, if Qtype is unknown to the Responder, it must return a NI
Reply with ICMPv6 Code = 2 and no Reply Data. The Responder should Reply with ICMPv6 Code = 2 and no Reply Data. The Responder should
rate-limit such replies as it would ICMPv6 error replies [2463, rate-limit such replies as it would ICMPv6 error replies [2463,
2.4(f)]. 2.4(f)].
Next, the Responder should decide whether to refuse an answer, based Next, the Responder should decide whether to refuse an answer, based
on local policy not addressed in this document. If an answer is on local policy. (See "Security Considerations" for recommended
refused, the Responder may send a NI Reply with ICMPv6 Code = 1 and default behavior.) If an answer is refused, the Responder may send
no Reply Data. Again, the Responder should rate-limit such replies a NI Reply with ICMPv6 Code = 1 and no Reply Data. Again, the
as it would ICMPv6 error replies [2463, 2.4(f)]. Responder should rate-limit such replies as it would ICMPv6 error
replies [2463, 2.4(f)].
Finally, if the Qtype is known and the response is allowed by local Finally, if the Qtype is known and the response is allowed by local
policy, the Responder must fill in the Flags and Reply Data of the policy, the Responder must fill in the Flags and Reply Data of the
NI Reply in accordance with the definition of the Qtype and transmit NI Reply in accordance with the definition of the Qtype and transmit
the NI Reply with an ICMPv6 source address equal to the Queried the NI Reply with an ICMPv6 source address equal to the Queried
Address, unless that address was an anycast or a multicast address. Address, unless that address was an anycast or a multicast address.
If the Queried Address was anycast or multicast, the source address If the Queried Address was anycast or multicast, the source address
for the Reply SHOULD be one belonging to the interface on which the for the Reply SHOULD be one belonging to the interface on which the
Query was received. Query was received.
If the Query was sent to an anycast or multicast address, If the Query was sent to an anycast or multicast address,
transmission of the Reply MUST be delayed by a random interval transmission of the Reply MUST be delayed by a random interval
between zero and MAX_ANYCAST_DELAY_TIME, as defined by IPv6 Neighbor between zero and MAX_ANYCAST_DELAY_TIME, as defined by IPv6 Neighbor
Discovery [2461]. Discovery [2461].
4. Defined Qtypes 5. Defined Qtypes
The following five Qtypes are defined. The first four (number 0 to The following five Qtypes are defined. The first four (number 0 to
3) MUST be supported by any implementation of this protocol. The 3) MUST be supported by any implementation of this protocol. The
last one SHOULD be supported by any implementation on an IPv4/IPv6 last one SHOULD be supported by any implementation on an IPv4/IPv6
dual-stack node and MAY be supported on an IPv6-only node. dual-stack node and MAY be supported on an IPv6-only node.
0 NOOP. 0 NOOP.
1 Supported Qtypes. 1 Supported Qtypes.
2 DNS Name. 2 Node Name.
3 Node Addresses. 3 Node Addresses.
4 IPv4 Addresses. 4 IPv4 Addresses.
4.1. NOOP 5.1. NOOP
This NI type has no defined flags and never has a Data field. A This NI type has no defined flags and never has a Data field. A
Reply to a NI NOOP Query tells the Querier that a node with the Reply to a NI NOOP Query tells the Querier that a node with the
Queried Address is up and reachable, implements the Node Information Queried Address is up and reachable, implements the Node Information
protocol, and incidentally happens to reveal whether the Queried protocol, and incidentally happens to reveal whether the Queried
Address was an anycast address. On transmission, the ICMPv6 Code in Address was an anycast address. On transmission, the ICMPv6 Code in
a NOOP Query must be set to 1 and the Code in a NOOP Reply must be a NOOP Query must be set to 1 and the Code in a NOOP Reply must be
0. On reception of a NOOP Query or Reply, the Code must be ignored. 0. On reception of a NOOP Query or Reply, the Code must be ignored.
4.2. Supported Qtypes 5.2. Supported Qtypes
This Query contains no Data field. The Reply Data is a bit-vector This Query contains no Data field. The Reply Data is a bit-vector
showing which Qtypes are supported by the Responder. The Reply Data showing which Qtypes are supported by the Responder. The Reply Data
has two variant forms: uncompressed and compressed. The has two variant forms: uncompressed and compressed. The
uncompressed Data format is one or more complete 32-bit words, each uncompressed Data format is one or more complete 32-bit words, each
word a bitmask with the low-order bit in each word corresponding to word a bitmask with the low-order bit in each word corresponding to
the lowest numbered Qtype in a group of 32. The first word the lowest numbered Qtype in a group of 32. The first word
describes the Responder's support for Qtypes 0 to 31, the second describes the Responder's support for Qtypes 0 to 31, the second
word 32 to 63, and so on. word 32 to 63, and so on.
skipping to change at page 7, line 37 skipping to change at page 8, line 9
In a Query, a C-flag set to 1 indicates that the Querier will accept In a Query, a C-flag set to 1 indicates that the Querier will accept
the compressed form of the Reply Data. In a Reply, a C-flag set to the compressed form of the Reply Data. In a Reply, a C-flag set to
1 indicates that the Reply Data is compressed. The compressed form 1 indicates that the Reply Data is compressed. The compressed form
MAY be used in a Reply only if the Query had the C-flag set. MAY be used in a Reply only if the Query had the C-flag set.
Implementations of this specification SHOULD support the compressed Implementations of this specification SHOULD support the compressed
form and if they do, SHOULD set the C-flag in all Supported Qtypes form and if they do, SHOULD set the C-flag in all Supported Qtypes
Queries and SHOULD use the compressed form in Supported Qtypes Queries and SHOULD use the compressed form in Supported Qtypes
Replies (when allowed by the C-flag in the query) if doing so would Replies (when allowed by the C-flag in the query) if doing so would
avoid fragmentation or save significant space in the Reply. avoid fragmentation or save significant space in the Reply.
4.3. DNS Name 5.3. Node Name
The NI DNS Name Query requests the fully-qualified or single- The NI Node Name Query requests the fully-qualified or single-
component name corresponding to the Subject Address or Name. The component name corresponding to the Subject Address or Name. The
Reply Data has the following format. Reply Data has the following format.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TTL | | TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNS Names ... | | Node Names ... |
+ + + +
/ / / /
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TTL The number of seconds that the name may be cached. For TTL The number of seconds that the name may be cached. For
compatibility with DNS [1035], this is a 32-bit signed, compatibility with DNS [1035], this is a 32-bit signed,
2's-complement number, which must not be negative. 2's-complement number, which must not be negative.
DNS Names The fully-qualified or single-component name or names of Node Names The fully-qualified or single-component name or names of
the Responder which correspond(s) to the Subject Address the Responder which correspond(s) to the Subject Address
or Name, in DNS wire format [1035]. Each name MUST be or Name, in DNS wire format [1035]. Each name MUST be
fully-qualified if the responder knows the domain fully-qualified if the responder knows the domain
suffix, and otherwise be a single DNS label followed by suffix, and otherwise be a single DNS label followed by
two zero-length labels. two zero-length labels.
When multiple DNS names are returned, DNS name When multiple node names are returned and more than one
compression [1035] SHOULD be used, and the offsets are of them is fully-qualified, DNS name compression [1035]
counted from the first octet of the Data field. An SHOULD be used, and the offsets are counted from the
offset of 4, for example, will point to the beginning of first octet of the Data field. An offset of 4, for
the first name. example, will point to the beginning of the first name.
The Responder must fill in the TTL field of the Reply with a The Responder must fill in the TTL field of the Reply with a
meaningful value if possible. That value should be one of the meaningful value if possible. That value should be one of the
following. following.
The remaining lifetime of a DHCP lease on the Subject Address; The remaining lifetime of a DHCP lease on the Subject Address;
The remaining Valid Lifetime of a prefix from which the Subject The remaining Valid Lifetime of a prefix from which the Subject
Address was derived through Stateless Autoconfiguration [2461, Address was derived through Stateless Autoconfiguration [2461,
2462]; 2462];
The TTL of an existing AAAA or A6 record which associates the The TTL of an existing AAAA or A6 record which associates the
Subject Address with the DNS Name being returned. Subject Address with the Node Name being returned.
If the Responder returns multiple names but considers one name to be If the Responder returns multiple names but considers one name to be
official or canonical, that name MUST be placed immediately after official or canonical, that name MUST be placed immediately after
the TTL. the TTL.
Only one TTL is included in the reply. If the Responder considers Only one TTL is included in the reply. If the Responder considers
different names to be cacheable for different times, the TTL field different names to be cacheable for different times, the TTL field
must be set no larger than the minimum of those times. must be set no larger than the minimum of those times. In any case,
the TTL returned MUST be no greater than 2^31-1, even if the
responding node's conception of the lifetime is longer (or
infinite).
If the Responder does not know its name at all it MUST send a Reply If the Responder does not know its name at all it MUST send a Reply
with TTL=0 and no DNS Names. The Querier will be able to determine with TTL=0 and no Node Names (or a Reply with Code=1 indicating
from the packet length that the Data field contains only a TTL. refusal to answer). The Querier will be able to determine from the
packet length that the Data field contains no names.
One Flag bit is defined, in the Reply only. One Flag bit is defined, in the Reply only.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Qtype=2 | unused |T| | Qtype=2 | unused |T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A T-flag set to 1 in a NI DNS Name Reply indicates that the TTL A T-flag set to 1 in a NI Node Name Reply indicates that the TTL
field contains a meaningful value. If the T-flag is 0, the TTL field contains a meaningful value. If the T-flag is 0, the TTL
SHOULD be set to zero by the Responder and MUST be ignored by the SHOULD be set to zero by the Responder and MUST be ignored by the
Querier. Querier.
If a name rather than an address was the Subject of the Query, the If a name rather than an address was the Subject of the Query, the
T-flag MUST be zero and the TTL SHOULD be zero. T-flag MUST be zero and the TTL SHOULD be zero.
The information in a NI DNS Name Reply with T-flag 1 may be cached The information in a NI Node Name Reply with T-flag 1 may be cached
and used for the period indicated by that TTL. If a Reply has no and used for the period indicated by that TTL. If a Reply has no
TTL (T-flag 0), the information in that Reply must not be used more TTL (T-flag 0), the information in that Reply must not be used more
than once. If the Query was sent by a DNS server on behalf of a DNS than once. If the Query was sent by a DNS server on behalf of a DNS
client, the result may be returned to that client as a DNS response client, the result may be returned to that client as a DNS response
with TTL zero. However, if the server has the matching AAAA record, with TTL zero. However, if the server has the matching AAAA record,
either in cache or in an authoritative zone, then the TTL of that either in cache or in an authoritative zone, then the TTL of that
record may be used as the missing TTL of the NI DNS Name Reply and record may be used as the missing TTL of the NI Node Name Reply and
the information in the reply may be cached and used for that period. the information in the reply may be cached and used for that period.
It would be an implementation choice for a server to perform a DNS It would be an implementation choice for a server to perform a DNS
query for the AAAA or A6 record that matches a received NI DNS Name query for the AAAA or A6 records that match a received NI Node Name
Reply. This might be done to obtain a TTL to make the Reply Reply. This might be done to obtain a TTL to make the Reply
cacheable or in anticipation of such a AAAA query from the client cacheable or in anticipation of such a DNS query from the client
that caused the DNS Name Query. that caused the Node Name Query.
4.3.1. Discussion 5.3.1. Discussion
Because a node can only answer a DNS Name Request when it is up and Because a node can only answer a Node Name Request when it is up and
reachable, it may be useful to create a proxy responder for a group reachable, it may be useful to create a proxy responder for a group
of nodes, for example a subnet or a site. Such a mechanism is not of nodes, for example a subnet or a site. Such a mechanism is not
addressed here. addressed here.
IPsec can be applied to NI DNS Name messages to achieve greater IPsec can be applied to NI Node Name messages to achieve greater
trust in the information obtained, but such a need may be obviated trust in the information obtained, but such a need may be obviated
by applying IPsec directly to some other communication which is by applying IPsec directly to some other communication which is
going on (or contemplated) between the Querier and Responder. going on (or contemplated) between the Querier and Responder.
4.4. Node Addresses 5.4. Node Addresses
The NI Node Addresses Query requests some set of the Responder's The NI Node Addresses Query requests some set of the Responder's
IPv6 unicast addresses. The Reply Data is a sequence of 128-bit IPv6 unicast addresses. The Reply Data is a sequence of 128-bit
IPv6 addresses, each address preceded by separate a 32-bit TTL IPv6 addresses, each address preceded by separate a 32-bit TTL
value, with Preferred addresses listed before Deprecated addresses value, with Preferred addresses listed before Deprecated addresses
[2461], but otherwise in no special order. Five flag bits are [2461], but otherwise in no special order. Five flag bits are
defined in the Query, and six in the Reply. defined in the Query, and six in the Reply.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
skipping to change at page 10, line 47 skipping to change at page 11, line 14
interface) which has the Subject Address, or which are interface) which has the Subject Address, or which are
associated with the Subject Name. associated with the Subject Name.
T Defined in a Reply only, indicates that the set of addresses is T Defined in a Reply only, indicates that the set of addresses is
incomplete for space reasons. incomplete for space reasons.
Flags G, S, L, C and A are copied from a Query to the corresponding Flags G, S, L, C and A are copied from a Query to the corresponding
Reply. Reply.
The TTL associated with each address are to be determined by the The TTL associated with each address are to be determined by the
rules in section 4.3, applied to the returned address rather than rules in section 5.3, applied to the returned address rather than
the Subject. If no meaningful caching time can be given for an the Subject. If no meaningful caching time can be given for an
address, the corresponding TTL field MUST be zero. address, the corresponding TTL field MUST be zero.
Each address with non-zero TTL in a NI Node Address Reply may be Each address with non-zero TTL in a NI Node Address Reply may be
cached and used for the period indicated by that TTL. If the TTL is cached and used for the period indicated by that TTL. If the TTL is
zero, the corresponding address must not be used more than once. If zero, the corresponding address must not be used more than once. If
the Query was sent by a DNS server on behalf of a DNS client, the the Query was sent by a DNS server on behalf of a DNS client, the
result may be returned to that client as a DNS response with TTL result may be returned to that client as a DNS response with TTL
zero. zero.
IPv4-mapped addresses can only be returned by a Node Information IPv4-mapped addresses can only be returned by a Node Information
proxy, since they represent addresses of IPv4-only nodes, which proxy, since they represent addresses of IPv4-only nodes, which
perforce do not implement this protocol. perforce do not implement this protocol.
4.5. IPv4 Addresses 5.5. IPv4 Addresses
The NI IPv4 Addresses Query requests some set of the Responder's The NI IPv4 Addresses Query requests some set of the Responder's
IPv4 unicast addresses. The Reply Data is a sequence of 32-bit IPv4 IPv4 unicast addresses. The Reply Data is a sequence of 32-bit IPv4
addresses, each address preceded by a 32-bit TTL value. One flag addresses, each address preceded by a 32-bit TTL value. One flag
bit is defined in the Query, and two in the Reply. bit is defined in the Query, and two in the Reply.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Qtype=4 | unused |A|T| | Qtype=4 | unused |A|T|
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requested. If 0, only those addresses are requested which requested. If 0, only those addresses are requested which
belong to the interface (or any one interface) which has the belong to the interface (or any one interface) which has the
Subject Address. Subject Address.
T Defined in a Reply only, indicates that the set of addresses is T Defined in a Reply only, indicates that the set of addresses is
incomplete for space reasons. incomplete for space reasons.
Flag A is copied from a Query to the corresponding Reply. Flag A is copied from a Query to the corresponding Reply.
The TTL associated with each address are to be determined by the The TTL associated with each address are to be determined by the
rules in section 4.3, applied to the returned address rather than rules in section 5.3, applied to the returned address rather than
the Subject, excluding the autoconfiguration Valid Lifetime. If no the Subject, excluding the autoconfiguration Valid Lifetime. If no
meaningful caching time can be given for an address, the meaningful caching time can be given for an address, the
corresponding TTL field MUST be zero. corresponding TTL field MUST be zero.
Each address with non-zero TTL in a NI IPv4 Address Reply may be Each address with non-zero TTL in a NI IPv4 Address Reply may be
cached and used for the period indicated by that TTL. If the TTL is cached and used for the period indicated by that TTL. If the TTL is
zero, the corresponding address must not be used more than once. If zero, the corresponding address must not be used more than once. If
the Query was sent by a DNS server on behalf of a DNS client, the the Query was sent by a DNS server on behalf of a DNS client, the
result may be returned to that client as a DNS response with TTL result may be returned to that client as a DNS response with TTL
zero. zero.
4.5.1. Discussion 5.5.1. Discussion
It is possible that a node may treat IPv4 interfaces and IPv6 It is possible that a node may treat IPv4 interfaces and IPv6
interfaces as distinct, even though they are associated with the interfaces as distinct, even though they are associated with the
same hardware. When such a node is responding to a NI Query having same hardware. When such a node is responding to a NI Query having
a Subject Address of one type requesting the other type, and the a Subject Address of one type requesting the other type, and the
Query has the A flag set to 0, it SHOULD consider IP interfaces, Query has the A flag set to 0, it SHOULD consider IP interfaces,
other than tunnels, associated with the same hardware as being the other than tunnels, associated with the same hardware as being the
same interface. same interface.
5. IANA Considerations 6. IANA Considerations
ICMPv6 type values 139 and 140 have been assigned by IANA for this ICMPv6 type values 139 and 140 have been assigned by IANA for this
protocol. This document defines three values of the ICMPv6 Code protocol. This document defines three values of the ICMPv6 Code
field for each of these ICMPv6 Type values. Additional Code values field for each of these ICMPv6 Type values. Additional Code values
may be defined only by IETF Consensus [2434]. may be defined only by IETF Consensus [2434].
This document defines five values of Qtype, numbers 0 through 4. This document defines five values of Qtype, numbers 0 through 4.
Following the policies outlined in "Guidelines for Writing an IANA Following the policies outlined in "Guidelines for Writing an IANA
Considerations Section in RFCs" [2434], new values, and their Considerations Section in RFCs" [2434], new values, and their
associated Flags and Reply Data, may be defined as follows. associated Flags and Reply Data, may be defined as follows.
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Qtypes 1024 through 4095, First Come First Served. Qtypes 1024 through 4095, First Come First Served.
Qtypes 4096 through 65535, Private Use. Qtypes 4096 through 65535, Private Use.
Users of Private Use values should note that values above 8000 to Users of Private Use values should note that values above 8000 to
9000 are likely to lead to fragmentation of "Supported Qtypes" 9000 are likely to lead to fragmentation of "Supported Qtypes"
Replies unless the compressed form of the Reply Data is used. Replies unless the compressed form of the Reply Data is used.
Assignment of the multicast address prefix FF02:0:0:0:0:2::/96 used Assignment of the multicast address prefix FF02:0:0:0:0:2::/96 used
in section 3 as a destination for IPv6 Node Information Queries is in section 4 as a destination for IPv6 Node Information Queries is
requested. requested.
6. Security Considerations 7. Security Considerations
This protocol has the potential of revealing information useful to a
would-be attacker. An implementation of this protocol SHOULD have a
default configuration which refuses to answer queries from global-
scope [2373] adresses.
Implementations SHOULD apply rate-limiting to NI responses to avoid
being used in a denial of service attack.
The anti-spoofing Nonce does not give any protection from spoofers The anti-spoofing Nonce does not give any protection from spoofers
who can snoop the Query or the Reply. who can eavesdrop the Query or the Reply.
In a large Internet with relatively frequent renumbering, the In a large Internet with relatively frequent renumbering, the
maintenance of of KEY and SIG records [2535] in the zones used for maintenance of of KEY and SIG records [2535] in the zones used for
address-to-name translations will be no easier than the maintenance address-to-name translations will be no easier than the maintenance
of the NS, SOA and PTR records themselves, which already appears to of the NS, SOA and PTR records themselves, which already appears to
be difficult in many cases. The author expects, therefore, that be difficult in many cases. The author expects, therefore, that
address-to-name mappings, either through the original DNS mechanism address-to-name mappings, either through the original DNS mechanism
or through this new mechanism, will generally be used as only a hint or through this new mechanism, will generally be used as only a hint
to find more trustworthy information using the returned name as an to find more trustworthy information using the returned name as an
index. index.
7. Acknowledgments 8. Acknowledgments
Alain Durand contributed to this specification and valuable feedback Alain Durand contributed to this specification and valuable feedback
and implementation experience was provided by Jun-Ichiro Hagino and and implementation experience was provided by Jun-Ichiro Hagino and
Tatuya Jinmei. This document is not the first proposal of a direct Tatuya Jinmei. Other useful comments were received from Robert Elz
query mechanism for address-to-name translation. The idea had been and Keith Moore.
discussed briefly in the IPng working group and RFC 1788 [1788]
describes such a mechanism for IPv4.
8. References This document is not the first proposal of a direct query mechanism
for address-to-name translation. The idea had been discussed
briefly in the IPng working group and RFC 1788 [1788] describes such
a mechanism for IPv4.
9. References
[1034] P. Mockapetris, "Domain Names - Concepts and Facilities", RFC
1034, STD 13, November 1987.
[1035] P. Mockapetris, "Domain Names - Implementation and [1035] P. Mockapetris, "Domain Names - Implementation and
Specification", RFC 1035, STD 13, November 1987. Specification", RFC 1035, STD 13, November 1987.
[1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321, [1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992. April 1992.
[1788] W. Simpson, "ICMP Domain Name Messages", RFC 1788, April [1788] W. Simpson, "ICMP Domain Name Messages", RFC 1788, April
1995. 1995.
skipping to change at page 14, line 15 skipping to change at page 15, line 6
[2462] Thomson, S. and T. Narten, "IPv6 Stateless Address [2462] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998. Autoconfiguration", RFC 2462, December 1998.
[2463] Conta, A. and S. Deering, "Internet Control Message Protocol [2463] Conta, A. and S. Deering, "Internet Control Message Protocol
(ICMPv6) for the Internet Protocol Version 6 (IPv6) (ICMPv6) for the Internet Protocol Version 6 (IPv6)
Specification", RFC 2463, December 1998. Specification", RFC 2463, December 1998.
[2535] D. Eastlake 3rd, "Domain Name System Security Extensions", [2535] D. Eastlake 3rd, "Domain Name System Security Extensions",
RFC 2535, March 1999. RFC 2535, March 1999.
9. Author's Address 10. Author's Address
Matt Crawford Matt Crawford
Fermilab MS 368 Fermilab MS 368
PO Box 500 PO Box 500
Batavia, IL 60510 Batavia, IL 60510
USA USA
Phone: +1 630 840 3461 Phone: +1 630 840 3461
Email: crawdad@fnal.gov Email: crawdad@fnal.gov
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