Internet DRAFT - draft-wkumari-dnsop-defense-collision-mitigate
draft-wkumari-dnsop-defense-collision-mitigate
Network Working Group W. Kumari
Internet-Draft Google
Intended status: Informational November 22, 2013
Expires: May 26, 2014
A method for mitigating namespace collisions
draft-wkumari-dnsop-defense-collision-mitigate-03
Abstract
This document outlines a possible, but not recommended, method to
mitigate the effect of collisions in the DNS namespace by providing a
means for end users to disambiguate the conflict.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 26, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction / Background . . . . . . . . . . . . . . . . . . 2
2. Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Implementation / Disclaimers . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction / Background
Collisions in the DNS occur in multiple ways; one common case is that
an organization has used an sub-domain (foo) of their primary domain
(example.com) for corporate infrastructure, and then the string "foo"
is delegated as a TLD. When an employee of the organization enters
'www.foo', is the goal to reach a machine in the internal namespace
(www.foo.example.com) or the hostname 'www' in the 'foo' TLD?
This document describes a means of disambiguating these, and similar
cases.
Implementation of these methods are not recommended; they are
documented here to explain some of the pitfalls with approaches like
these.
2. Mitigation
The mitigation described in this document involves presenting the
multiple options to the user, and allowing them to indicate which of
the names is the one they were trying to reach.
The mitigation would lookup the name in multiple namespaces. When if
a conflict is detected, it would then provide a means for the user to
indicate which one of the colliding names they wish to connect to,
and return the disambiguated answer to the application. An
additional feature could be for the mitigation to cache the user's
choice, and / or provide a means to set priorities.
This could be accomplished in a number of ways, including:
Intercepting the resolution requests from the application in a
"shim" type library
Replacing the resolver library entirelyT
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Integrating this type of mitigation into applications (some web
browsers already do something similar to this)
Proxying the request to a server that provides an interstitial
page that allows the user to indicate the intended name (for
applications such as HTTP requests)
There are a number of issues with this solution, including but not
limited to:
o There may not be a human available to disambiguate the answer
(unattended machines, mail servers, etc.)
o The human / user may have no idea which is the correct choice,
especially in the case of a phishing attackor other malicious
intent
o The additional latency introduced may cause the originating
application to time out
o The user experience would be time consuming to select each site
and subsite intended (www.intranet, images.intranet, etc.)
o Caching the responses could lead to problems when the user changes
location (internal sites would fail when offsite, or otherwise
lead to incorrect sites being loaded)
For these and other reasons, implementation of this technique is not
recommended.
3. Implementation / Disclaimers
This document does not reference an implementation. Due to the
numerous issues described above, we do not recommend this solution be
implemented. We do not recommend that this be viewed as a solution
to the namespace collision problem.
This is a very slight mitigation. It should not be viewed as a
solution to the "namespace collision" issue.
4. IANA Considerations
This document contains no IANA considerations.
5. Security Considerations
While this method may make some users more aware of which version of
a name they are going to (and so careful users may avoid some
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phishing attacks), the security risks described above outweigh this
potential benefit.
There are numerous security implications in this approach, including
leaking internal names (secret-project.corp.example.com), users being
tricked into selecting the incorrect choice when trying to
disambiguate answers, etc.
For these reasons, it is not recommended that this solution be
deployed.
6. Acknowledgements
The authors wish to thank some folk, including Fred Baker, Bob
Braden, Carsten Bormann, Nevil Brownlee, Eric Burger, Brian
Carpenter, Benoit Claise, Keith Drage, Martin J. Duerst, David
Harrington, Paul Hoffamn, John Levine and Ted Lemon,
7. References
Appendix A. Changes / Author Notes.
[RFC Editor: Please remove this section before publication.]
From -00 to -01.
o Nothing changed in the template.
from -01 to -02
o Rewrite. Less flippant.
From -02 to -03:
o Changed to Informational. Suggestion from ISE:"I see only one
remaining thing - you've changed its Intended Status to
Experimental. I think Informational would be better, since
'Experimental' implies that you have an implementation and are
publishing the document so that others can try it too. "
Author's Address
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Warren Kumari
Google
1600 Amphitheatre Parkway
Mountain View, CA 94043
US
Email: warren@kumari.net
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