draft-ietf-dnsext-obsolete-iquery-04.txt   rfc3425.txt 
DNSEXT Working Group David C Lawrence
INTERNET-DRAFT Nominum
<draft-ietf-dnsext-obsolete-iquery-04.txt> July 2002
Updates: RFC 1035
Obsoleting IQUERY
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as ``work in progress.''
The list of current Internet-Drafts can be accessed at Network Working Group D. Lawrence
http://www.ietf.org/ietf/1id-abstracts.txt Request for Comments: 3425 Nominum
Updates: 1035 November 2002
Category: Standards Track
The list of Internet-Draft Shadow Directories can be accessed at Obsoleting IQUERY
http://www.ietf.org/shadow.html
Comments should be sent to the authors or the DNSEXT WG mailing list Status of this Memo
namedroppers@ops.ietf.org.
This draft expires on 14 January 2003. This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All rights reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract Abstract
The IQUERY method of performing inverse DNS lookups, specified in The IQUERY method of performing inverse DNS lookups, specified in RFC
RFC 1035, has not been generally implemented and has usually been 1035, has not been generally implemented and has usually been
operationally disabled where it has been implemented. Both reflect operationally disabled where it has been implemented. Both reflect a
a general view in the community that the concept was unwise and general view in the community that the concept was unwise and that
that the widely-used alternate approach of using PTR queries and the widely-used alternate approach of using pointer (PTR) queries and
reverse-mapping records is preferable. Consequently, this document reverse-mapping records is preferable. Consequently, this document
deprecates the IQUERY operation and updates RFC 1035 to declare it deprecates the IQUERY operation, declaring it entirely obsolete.
entirely obsolete. This document updates RFC 1035.
1 - Introduction 1 - Introduction
As specified in RFC 1035 (section 6.4), the IQUERY operation for As specified in RFC 1035 (section 6.4), the IQUERY operation for DNS
DNS queries is used to look up the name(s) which are associated queries is used to look up the name(s) which are associated with the
with the given value. The value being sought is provided in the given value. The value being sought is provided in the query's
query's answer section and the response fills in the question answer section and the response fills in the question section with
section with one or more 3-tuples of type, name and class. one or more 3-tuples of type, name and class.
As noted in [RFC1035], section 6.4.3, inverse query processing can As noted in [RFC1035], section 6.4.3, inverse query processing can
put quite an onerous burden on a server. A server would need to put quite an arduous burden on a server. A server would need to
perform either an exhaustive search of its database or maintain a perform either an exhaustive search of its database or maintain a
separate database that is keyed by the values of the primary separate database that is keyed by the values of the primary
database. Both of these approaches could strain system resource database. Both of these approaches could strain system resource use,
use, particularly for servers that are authoritative for millions particularly for servers that are authoritative for millions of
of names. names.
Response packet from these megaservers could be exceptionally Response packets from these megaservers could be exceptionally large,
large, and easily run into megabyte sizes. For example, using and easily run into megabyte sizes. For example, using IQUERY to
IQUERY to find every domain that is delegated to one of the find every domain that is delegated to one of the nameservers of a
nameservers of a large ISP could return tens of thousands of large ISP could return tens of thousands of 3-tuples in the question
3-tuples in the question section. This could easily be used to section. This could easily be used to launch denial of service
launch denial of service attacks. attacks.
Operators of servers that do support IQUERY in some form (such as Operators of servers that do support IQUERY in some form (such as
very old BIND 4 servers) generally opt to disable it. This is very old BIND 4 servers) generally opt to disable it. This is
largely due to bugs in insufficiently-exercised code, or concerns largely due to bugs in insufficiently-exercised code, or concerns
about exposure of large blocks of names in their zones by probes about exposure of large blocks of names in their zones by probes such
such as inverse MX queries. as inverse MX queries.
IQUERY is also somewhat inherently crippled by being unable to tell IQUERY is also somewhat inherently crippled by being unable to tell a
a requestor where it needs to go to get the information that was requester where it needs to go to get the information that was
requested. The answer is very specific to the single server that requested. The answer is very specific to the single server that was
was queried. This is sometimes a handy diagnostic tool, but queried. This is sometimes a handy diagnostic tool, but apparently
apparently not enough so that server operators like to enable it, not enough so that server operators like to enable it, or request
or request implementation where it's lacking. implementation where it is lacking.
No known clients use IQUERY to provide any meaningful service. The No known clients use IQUERY to provide any meaningful service. The
only common reverse mapping support on the Internet, mapping only common reverse mapping support on the Internet, mapping address
address records to names, is provided through the use of PTR records to names, is provided through the use of pointer (PTR)
records in the in-addr.arpa tree and has served the community well records in the in-addr.arpa tree and has served the community well
for many years. for many years.
Based on all of these factors, this draft proposes that the IQUERY Based on all of these factors, this document recommends that the
operation for DNS servers be officially obsoleted. IQUERY operation for DNS servers be officially obsoleted.
2 - Requirements 2 - Requirements
The key word "SHOULD" in this document is to be interpreted as The key word "SHOULD" in this document is to be interpreted as
described in RFC 2119, namely that there may exit valid reasons described in BCP 14, RFC 2119, namely that there may exist valid
to ignore a particular item, but the full implications must be reasons to ignore a particular item, but the full implications must
understood and carefully weighed before choosing a different course. be understood and carefully weighed before choosing a different
course.
3 - Effect on RFC 1035 3 - Effect on RFC 1035
The effect of this document is to change the definition of opcode 1 The effect of this document is to change the definition of opcode 1
from that originally defined in section 4.1.1 of RFC 1035, and to from that originally defined in section 4.1.1 of RFC 1035, and to
entirely supersede section 6.4 (including subsections) of RFC 1035. entirely supersede section 6.4 (including subsections) of RFC 1035.
The definition of opcode 1 is hereby changed to: The definition of opcode 1 is hereby changed to:
"1 an inverse query (IQUERY) (obsolete)" "1 an inverse query (IQUERY) (obsolete)"
The text in section 6.4 of RFC 1035 is now considered obsolete. The text in section 6.4 of RFC 1035 is now considered obsolete. The
The following is an applicability statement regarding the IQUERY following is an applicability statement regarding the IQUERY opcode:
opcode:
Inverse queries using the IQUERY opcode were originally described Inverse queries using the IQUERY opcode were originally described as
as the ability to look up the names that are associated with a the ability to look up the names that are associated with a
particular RR. Their implementation was optional and never particular Resource Record (RR). Their implementation was optional
achieved widespread use. Therefore IQUERY is now obsolete, and and never achieved widespread use. Therefore IQUERY is now obsolete,
name servers SHOULD return a "Not Implemented" error when an IQUERY and name servers SHOULD return a "Not Implemented" error when an
request is received. IQUERY request is received.
4 - Security Considerations 4 - Security Considerations
Since this document obsoletes an operation that was once available, Since this document obsoletes an operation that was once available,
it is conceivable that someone was using it as the basis of a it is conceivable that someone was using it as the basis of a
security policy. However, since the most logical course for such a security policy. However, since the most logical course for such a
policy to take in the face of a lack of positive response from a policy to take in the face of a lack of positive response from a
server is to deny authentication/authorization, it is highly server is to deny authentication/authorization, it is highly unlikely
unlikely that removing support for IQUERY will open any new that removing support for IQUERY will open any new security holes.
security holes.
Note that if IQUERY is not obsoleted, securing the responses with Note that if IQUERY is not obsoleted, securing the responses with DNS
DNSSEC is extremely difficult without out-on-the-fly digital signing. Security (DNSSEC) is extremely difficult without out-on-the-fly
digital signing.
5 - IANA Considerations 5 - IANA Considerations
The IQUERY opcode of 1 should be permanently retired, not to be The IQUERY opcode of 1 should be permanently retired, not to be
assigned to any future opcode. assigned to any future opcode.
6 - Acknowledgments 6 - Acknowledgments
Olafur Gudmundsson was the instigator for this action. Olafur Gudmundsson instigated this action. Matt Crawford, John
Matt Crawford, John Klensin, Erik Nordmark and Keith Moore Klensin, Erik Nordmark and Keith Moore contributed some improved
contributed some improved wording as the matter of how to handle wording in how to handle obsoleting functionality described by an
obsoleting functionality described by an Internet Standard. Internet Standard.
7 - References 7 - References
[RFC1035] P. Mockapetris, ``Domain Names - Implementation and [RFC1035] Mockapetris, P., "Domain Names - Implementation and
Specification'', STD 13, RFC 1035, November 1987. Specification", STD 13, RFC 1035, November 1987.
[RFC2026] S. Bradner, ``The Internet Standards Process -- Revision 3'', [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
BCP 9, RFC 2026, October 1996. 3", BCP 9, RFC 2026, October 1996.
[RFC2119] S. Bradner, ``Key Words for Use in RFCs to Indicate [RFC2119] Bradner, S., "Key Words for Use in RFCs to Indicate
Requirement Levels'', BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
8 - Author's Address 8 - Author's Address
David C Lawrence David C Lawrence
Nominum, Inc. Nominum, Inc.
2385 Bay Rd 2385 Bay Rd
Redwood City CA 94063 Redwood City CA 94063
USA USA
Phone: +1.650.779.6042 Phone: +1.650.779.6042
EMail: tale@nominum.com EMail: tale@nominum.com
9 - Full Copyright Statement 9 - Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
skipping to change at page 4, line 53 skipping to change at page 5, line 31
English. English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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