draft-ietf-dnsext-ad-is-secure-00.txt   draft-ietf-dnsext-ad-is-secure-01.txt 
DNSEXT Working Group Brian Wellington (Nominum) DNSEXT Working Group Brian Wellington (Nominum)
INTERNET-DRAFT Olafur Gudmundsson (NAI Labs) INTERNET-DRAFT Olafur Gudmundsson (NAI Labs)
<draft-ietf-dnsext-ad-is-secure-00.txt> November 2000 <draft-ietf-dnsext-ad-is-secure-01.txt> January 2001
Updates: RFC 2535 Updates: RFC 2535
Redefinition of DNS AD bit Redefinition of DNS AD bit
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. all provisions of Section 10 of RFC2026.
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
Comments should be sent to the authors or the DNSEXT WG mailing list Comments should be sent to the authors or the DNSEXT WG mailing list
namedroppers@ops.ietf.org namedroppers@ops.ietf.org
This draft expires on May 17, 2001. This draft expires on July 19, 2001.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2000). All rights reserved. Copyright (C) The Internet Society (2001). All rights reserved.
Abstract Abstract
Based on implementation experience, the current definition of the AD Based on implementation experience, the current definition of the AD
bit in the DNS header is not useful. This draft changes the bit in the DNS header is not useful. This draft changes the
specification so that the AD bit is only set on answers where specification so that the AD bit is only set on answers where
signatures have been cryptographically verified. signatures have been cryptographically verified.
1 - Introduction 1 - Introduction
Familiarity with the DNS system [RFC1034, RFC1035] and DNS security Familiarity with the DNS system [RFC1035] and DNS security extensions
extensions [RFC2535] is helpful but not necessary. [RFC2535] is helpful but not necessary.
As specified in RFC 2535 (section 6.1), the AD bit indicates in a As specified in RFC 2535 (section 6.1), the AD bit indicates in a
response that all the data included in the answer and authority response that all the data included in the answer and authority
portion of the response has been authenticated by the server portion of the response has been authenticated by the server
according to the policies of that server. This is not especially according to the policies of that server. This is not especially
useful in practice, since a conformant server should never reply with useful in practice, since a conformant server should never reply with
data that failed its security policy. data that failed its security policy.
This draft proposes to redefine the AD bit such that it is only set This draft proposes to redefine the AD bit such that it is only set
if all data in the response has been cryptographically verified. if all data in the response has been cryptographically verified.
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unset. unset.
The AD bit MUST NOT be set on a response unless all of the RRsets in The AD bit MUST NOT be set on a response unless all of the RRsets in
the answer and authority sections are Authenticated. the answer and authority sections are Authenticated.
A resolver MUST NOT blindly trust the AD bit unless it communicates A resolver MUST NOT blindly trust the AD bit unless it communicates
with the server over secure transport mechanism or using message with the server over secure transport mechanism or using message
authentication such as TSIG[RFC2845] or SIG(0)[RFC2931], and the authentication such as TSIG[RFC2845] or SIG(0)[RFC2931], and the
resolver policy is that it can trust the server. resolver policy is that it can trust the server.
A DNS server following this modified specification will only set the A DNS server following this modified specification will only set the
AD bit when it has verified the data in the answer. In the case of a AD bit when it has cryptographically verified the data in the answer.
primary server for a secure zone, the data MAY be considered In the case of a primary server for a secure zone, the data MAY be
Authenticated, depending on local policy. Secondary servers SHOULD considered Authenticated, depending on local policy. Secondary
NOT consider data Authenticated unless the zone was transfered servers SHOULD NOT consider data Authenticated unless the zone was
securely or the data was verified. transfered securely or the data was verified.
3 - Interpretation of the AD bit 3 - Interpretation of the AD bit
A response containing data marked Insecure in the answer or authority A response containing data marked Insecure in the answer or authority
section will never have the AD bit set. In this case, the resolver section will never have the AD bit set. In this case, the resolver
SHOULD treat the data as Insecure whether or not SIG records are SHOULD treat the data as Insecure whether or not SIG records are
present. present.
4 - Security Considerations: 4 - Security Considerations:
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trusts the value of the AD bit, it must be sure that the server is trusts the value of the AD bit, it must be sure that the server is
using the updated definition. using the updated definition.
5 - IANA Considerations: 5 - IANA Considerations:
None None
6 - Acknowledgments: 6 - Acknowledgments:
The following people have provided input on this document: Andreas The following people have provided input on this document: Andreas
Gustafsson, Bob Halley, Steven Jacob, Gustafsson, Bob Halley, Steven Jacob.
References: References:
[RFC1035] P. Mockapetris, ``Domain Names - Implementation and [RFC1035] P. Mockapetris, ``Domain Names - Implementation and
Specification'', STD 13, RFC 1035, November 1987. Specification'', STD 13, RFC 1035, November 1987.
[RFC2535] D. Eastlake, ``Domain Name System Security Extensions'', RFC [RFC2535] D. Eastlake, ``Domain Name System Security Extensions'', RFC
2535, March 1999. 2535, March 1999.
[RFC2845] P. Vixie, O. Gudmundsson, D. Eastlake, B. Wellington, [RFC2845] P. Vixie, O. Gudmundsson, D. Eastlake, B. Wellington,
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Brian Wellington Olafur Gudmundsson Brian Wellington Olafur Gudmundsson
Nominum Inc. NAI Labs Nominum Inc. NAI Labs
950 Charter Street 3060 Washington Road (Rt. 97) 950 Charter Street 3060 Washington Road (Rt. 97)
Redwood City, CA, 94063 Glenwood, MD, 21738 Redwood City, CA, 94063 Glenwood, MD, 21738
USA USA USA USA
+1 650 381 6022 +1 443 259 2389 +1 650 381 6022 +1 443 259 2389
<Brian.Wellington@nominum.com> <ogud@tislabs.com> <Brian.Wellington@nominum.com> <ogud@tislabs.com>
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved. Copyright (C) The Internet Society (2001). 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
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
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