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Versions: 00 01 draft-ietf-dnsop-dnssec-roadblock-avoidance

DNSOP                                                        W. Hardaker
Internet-Draft                                                   Parsons
Intended status: Best Current Practice                    O. Gudmundsson
Expires: July 20, 2014                                     Shinkuro Inc.
                                                         S. Krishnaswamy
                                                                 Parsons
                                                        January 16, 2014


                       DNSSEC Roadblock Avoidance
         draft-hardaker-dnsop-dnssec-roadblock-avoidance-01.txt

Abstract

   This document describes problems that a DNSSEC aware resolver/
   application might run into within a non-compliant infrastructure.  It
   outline potential detection and mitigation techniques.  The scope of
   the document is to create a shared approache to detect and overcome
   network issues that a DNSSEC software/system may face.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on July 20, 2014.

Copyright Notice

   Copyright (c) 2014 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Background  . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Notation  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Detecting DNSSEC Non-Compilance . . . . . . . . . . . . . . .   4
     3.1.  Determining DNSSEC support in neighboring recursive
           resolvers . . . . . . . . . . . . . . . . . . . . . . . .   4
       3.1.1.  Supports UDP answers  . . . . . . . . . . . . . . . .   4
       3.1.2.  Supports TCP answers  . . . . . . . . . . . . . . . .   5
       3.1.3.  Supports EDNS0  . . . . . . . . . . . . . . . . . . .   5
       3.1.4.  Supports the DO bit . . . . . . . . . . . . . . . . .   5
       3.1.5.  Supports the AD bit . . . . . . . . . . . . . . . . .   6
       3.1.6.  Returns RRsig for signed answer . . . . . . . . . . .   6
       3.1.7.  Supports querying for DNSKEY records  . . . . . . . .   6
       3.1.8.  Supports querying for DS records  . . . . . . . . . .   7
       3.1.9.  Supports negative answers with NSEC records . . . . .   7
       3.1.10. Supports negative answers with NSEC3 records  . . . .   7
       3.1.11. Supports queries where DNAME records lead to an
               answer  . . . . . . . . . . . . . . . . . . . . . . .   8
       3.1.12. Permissive DNSSEC . . . . . . . . . . . . . . . . . .   8
       3.1.13. UDP size limits . . . . . . . . . . . . . . . . . . .   8
       3.1.14. Supports Unknown RRtypes  . . . . . . . . . . . . . .   8
     3.2.  Direct Network Queries  . . . . . . . . . . . . . . . . .   9
       3.2.1.  Support for Remote UDP Over Port 53 . . . . . . . . .   9
       3.2.2.  Support for Remote UDP With Fragmentation . . . . . .   9
       3.2.3.  Support for Outbound TCP Over Port 53 . . . . . . . .  10
   4.  Aggregating The Results . . . . . . . . . . . . . . . . . . .  10
     4.1.  Resolver capability description . . . . . . . . . . . . .  10
   5.  Roadblock Avoidance . . . . . . . . . . . . . . . . . . . . .  11
     5.1.  Partial Resolver Usage  . . . . . . . . . . . . . . . . .  13
       5.1.1.  Known Insecure Lookups  . . . . . . . . . . . . . . .  13
       5.1.2.  Partial NSEC/NSEC3 Support  . . . . . . . . . . . . .  14
   6.  Start-Up and Network Connectivity Issues  . . . . . . . . . .  14
     6.1.  What To Do  . . . . . . . . . . . . . . . . . . . . . . .  14
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  15
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction




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   This document describes problems with DNSSEC ([RFC4034], [RFC4035])
   deployment due to non-compliant infrastructure.  It poses potential
   detection and mitigation techniques.

1.1.  Background

   Deployment of DNSSEC today is hampered by network components that
   make it difficult or sometimes impossible for validating resolvers to
   effectively obtain the DNSSEC data they need.  This can occur for
   many different reasons including

   o  Because neighboring recursive resolvers are not fully DNSSEC
      compliant

   o  Because resolvers are not even DNSSEC aware

   o  Because "middle-boxes" active block/restrict outbound traffic to
      the DNS port (53) either UDP and/or TCP .

   o  Network component in path does not allow UDP fragments

   o  etc...

   This document talks about ways a Host Validator can detect the state
   of the network it is attached to, and ways to hopefully circumvent
   the problems associated with the network defects it discovers.  The
   tests described in this document may be performed on any validating
   resolver to detect and prevent problems.  While these recomendations
   are mainly aimed at Host Validators it it prudent to perform these
   test from regular Validatating Resolvers before enabling just to make
   sure things work.

1.2.  Notation

   When we talk about a "Host Validator", this can either be a library
   that an application has linked in or an actual validating resolver
   running on the same machine.

   A variant of this is a "Validating Forwarding Resolver", which is a
   resolver that is configured to use upstream Resolvers if possible.
   Validating Forward Resolver needs to perform the same set of tests
   before using an upstream recursive resolver.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].





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2.  Goals

   The result of this work is intended to show how a Host Validator can
   detect the capabilities of a nearby recursive resolver, and work
   around any problems that could potentially affect DNSSEC resolution.
   This enables the Host Validator to make use of the caching
   functionality of the recursive resolver, which is desirable in that
   it decreases network traffic and improves response times.

   A Host Validator has two choices: it can wait to determine that it
   has problems with a recursive resolver based on the results that it
   is getting from real-world queries issued to it, or it can
   proactively test for problems (Section Section 3) to build a work
   around list ahead of time (Section Section 5).  There are pros and
   cons to both of these paths that are application specific, and this
   document does not attempt to provide guidance about whether proactive
   tests should or should not be used.  Either way, DNSSEC roadblock
   avoidance techniques ought to be used when needed and if possible.

3.  Detecting DNSSEC Non-Compilance

   A Host Validator may choose to determine early-on what bottlenecks
   exist that may hamper its ability to perform DNSSEC look-ups.  This
   section outlines tests that can be done to test certain features of
   the surrounding network.

   NOTE: when performing these tests against an address, we make the
   following assumtption about that address: It is a unicast address or
   an anycast cluster where all servers have identical configuration and
   connectivity.

3.1.  Determining DNSSEC support in neighboring recursive resolvers

   Ideally, a Host Validator can make use of the caching present in
   neighboring recursive resolvers.  This section discusses the tests
   that a neighboring recursive resolver MUST pass in order to be fully
   usable as a near-by DNS cache.

   Unless stated otherwise, all of the following tests SHOULD have the
   recursive flag set when sending out a query and SHOULD be sent over
   UDP.  Unless otherwise stated, the tests MUST NOT have the DO bit set
   or utilize any of the other DNSSEC related requirements, like EDNS0.
   The tests are designed to check for one feature at a time.

3.1.1.  Supports UDP answers

   Purpose: This tests basic DNS over UDP functionality to a resolver.




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   Test: A DNS request is sent to the resolver under test for an A
   record for a known existing domain, such as www.dnssec-tools.org.

   SUCCESS: A DNS response was received that contains an a A record in
   the answer section.  (The data itself does not need to be checked.)

   Note: an implementation MAY chose to not perform the rest of the
   tests if this test fails, as clearly the resolver under test is
   severely broken.

3.1.2.  Supports TCP answers

   Purpose: This tests basic TCP functionality to a resolver.

   Test: A DNS request is sent over TCP to the resolver under test for
   an A record for a known existing domain, such as www.dnssec-
   tools.org.

   SUCCESS: A DNS response was received that contains an A record in the
   answer section.  (The data itself does not need to be checked.)

3.1.3.  Supports EDNS0

   Purpose: Test whether a resolver properly supports the EDNS0
   extension option.

   Pre-requisite: "Supports UDP or TCP".

   Test: Send a request to the resolver under test for an A record for a
   known existing domain, such as www.dnssec-tools.org, with an EDNS0
   OPT record in the additional section.

   SUCCESS: A DNS response was received that contains an EDNS0 option
   with version number 0.

3.1.4.  Supports the DO bit

   Purpose: This tests whether a resolver has minimal support of the DO
   bit.

   Pre-requisite: "Supports EDNS0".

   Test: Send a request to the resolver under test for an A record for a
   known existing domain such as www.dnssec-tools.org.  Set the DO bit
   in the outgoing query.

   SUCCESS: A DNS response was received that contains the DO bit set.




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   Note: this only tests that the resolver sets the DO bit in the
   response.  Later checks will determine if the DO bit was actually
   made use of.  Some resolvers successfully pass this test because they
   simply copy the unknown flags into the response.  Don't worry,
   they'll fail the later tests.

3.1.5.  Supports the AD bit

   Purpose: This tests whether the resolver is a validating resolver.

   Pre-requisite: "Supports the DO bit".

   Test: Send a request to the resolver under test for an A record for a
   known existing domain in a DNSSEC signed zone which is verifiable to
   a configured trust anchor, such as www.dnssec-tools.org using the
   root's published DNSKEY or DS record as a trust anchor.  Set the DO
   bit in the outgoing query.

   SUCCESS: A DNS response was received that contains the AD bit set.

3.1.6.  Returns RRsig for signed answer

   Purpose: This tests whether a resolver will properly return RRSIG
   records when the DO bit is set.

   Pre-requisite: "Supports the DO bit".

   Test: Send a request to the resolver under test for an A record for a
   known existing domain in a DNSSEC signed zone, such as www.dnssec-
   tools.org.  Set the DO bit in the outgoing query.

   SUCCESS: A DNS response was received that contains at least one RRSIG
   record.

3.1.7.  Supports querying for DNSKEY records

   Purpose: This tests whether a resolver can query for and receive a
   DNSKEY record from a signed zone.

   Pre-requisite: "Supports the DO bit."

   Test: Send a request to the resolver under test for an DNSKEY record
   which is known to exist in a signed zone, such as dnssec-tools.org/
   DNSKEY.  Set the DO bit in the outgoing query.

   SUCCESS: A DNS response was received that contains a DNSKEY record in
   the answer section.




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   Note: Some DNSKEY RRset's are large and if the network path has
   problems with large answers this query may result in either false
   positive or false negative.  In general the DNSKEY queried for is a
   small enough to fit into 1220 byte answer, to avoid false negative
   result when TCP is disabled.  However, querying many zones will
   result in answers greater than 1220 bytes so ideally TCP MUST be
   available.

3.1.8.  Supports querying for DS records

   Purpose: This tests whether a resolver can query for and receive a DS
   record from a signed zone.

   Pre-requisite: "Supports the DO bit."

   Test: Send a request to the resolver under test for an DS record
   which is known to exist in a signed zone, such as dnssec-tools.org/
   DS.  Set the DO bit in the outgoing query.

   SUCCESS: A DNS response was received that contains a DS record in the
   answer section.

3.1.9.  Supports negative answers with NSEC records

   Purpose: This tests whether a resolver properly returns NSEC records
   for a non-existing domain in a DNSSEC signed zone.

   Pre-requisite: "Supports the DO bit."

   Test: Send a request to the resolver under test for an A record which
   is known to not existing, such as non-existent.test.dnssec-tools.org.
   Set the DO bit in the outgoing query.

   SUCCESS: A DNS response was received that contains an NSEC record.

   Note: The query issued in this test MUST be sent to a NSEC signed
   zone.  Getting back appropriate NSEC3 records does not indicate a
   failure, but a bad test.

3.1.10.  Supports negative answers with NSEC3 records

   Purpose: This tests whether a resolver properly returns NSEC3 records
   ([RFC5155]) for a non-existing domain in a DNSSEC signed zone.

   Pre-requisite: "Supports the DO bit."






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   Test: Send a request to the resolver under test for an A record which
   is known to be non-existent, such as non-existent.nsec3-ns.test
   .dnssec-tools.org.  Set the DO bit in the outgoing query.

   SUCCESS: A DNS response was received that contains an NSEC3 record.

   Note: The query issued in this test MUST be sent to a NSEC3 signed
   zone.  Getting back appropriate NSEC records does not indicate a
   failure, but a bad test.

3.1.11.  Supports queries where DNAME records lead to an answer

   Purpose: This tests whether a resolver can query for an A record in a
   zone with a known DNAME referral for the record's parent.

   Test: Send a request to the resolver under test for an A record which
   is known to exist in a signed zone within a DNAME referral child
   zone, such as good-a.dname-good-ns.test.dnssec-tools.net.

   SUCCESS: A DNS response was received that contains a DNAME in the
   answer section.  An RRSIG MUST also be received in the answer section
   that covers the DNAME record.

3.1.12.  Permissive DNSSEC

   Purpose: To see if a validating resolver is ignoring DNSSEC
   validation failures.

   Pre-requisite: Supports the AD bit.

   Test: ask for data from a broken DNSSEC delegation such as
   badsign-a.test.dnssec-tools.org.

   SUCCESS: A reply with the Rcode set to SERVFAIL

3.1.13.  UDP size limits

   TBD

3.1.14.  Supports Unknown RRtypes

   Purpose: Some DNS Resolvers/gateways only support some RRtypes.  This
   causes problems for applications that need recently defined types.

   Pre-requisite: "Supports UDP or TCP".






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   Test: Send a request for recently defined type or unknown type in the
   20000-22000 range, that resolves to a server that will return answer
   for all types, such as alltypes.res.dnssecready.org

   SUCCESS: A DNS response was retrieved that contains the type
   requested in the answer section.

3.2.  Direct Network Queries

   If need be, a Host Validator may need to make direct queries to
   authoritative servers or known Open Recursive Resolvers in order to
   collect data.  To do that, a number of key network features MUST be
   functional.

3.2.1.  Support for Remote UDP Over Port 53

   Purpose: This tests basic UDP functionality to outside the local
   network.

   Test: A DNS request is sent to a known distant authoritative server
   for a record known to be within that server's authoritative data.
   Example: send a query to the address of ns1.dnssec-tools.org for the
   www.dnssec-tools.org/A record.

   SUCCESS: A DNS response was received that contains an a A record in
   the answer section.

   Note: an implementation can use the local resolvers for determining
   the address of the name server that is authoritative for the given
   zone.  The recursive bit MAY be set for this request, but does not
   need to be.

3.2.2.  Support for Remote UDP With Fragmentation

   Purpose: This tests if the local network can receive fragmented UDP
   answers

   Pre-requisite: Local UDP > 1500 is possible

   Test: A DNS request is sent over UDP to a known distant DNS address
   asking for a record that has answer larger than 2000 bytes.  Example
   send a query for the dnssec-tools.org/DNSKEY record with the DO bit
   set in the outgoing query.

   Success: A DNS response was received that contains the large answer.

   Note: A failure in getting large answers over UDP is not a serious
   problem if TCP is working.



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3.2.3.  Support for Outbound TCP Over Port 53

   Purpose: This tests basic TCP functionality to outside the local
   network.

   Test: A DNS request is sent over TCP to a known distant authoritative
   server for a record known to be within that server's authoritative
   data.  Example: send a query to the address of ns1.dnssec-tools.org
   for the www.dnssec-tools.org/A record.

   SUCCESS: A DNS response was received that contains an a A record in
   the answer section.

   Note: an implementation can used the local resolvers for determining
   the address of the name server that is authoritative for the given
   zone.  The recursive bit MAY be set for this request, but does not
   need to be.

4.  Aggregating The Results

   Some conclusions can be drawn from the results of the above tests in
   an "aggregated" form.  This section defines some labels to assign to
   a resolver under test given the results of the tests run against
   them.

4.1.  Resolver capability description

   This section will group and label certain common results TBD

   Resolvers are classified into following broad behaviors:

   Validator:  The resolver passes all DNSSEC tests and had the AD bit
      appropriately set.

   DNSSEC Aware:  The resolver passes all DNSSEC tests, but does not
      appropriately set the AD bit on answers, indicating it is not
      validating.  A Host Validator will function fine using this
      resolver as a forwarder.

   Non-DNSSEC capable:  The resolver is not DNSSEC aware and will make
      it hard for a Host Validator to operate behind it.  It MAY be
      usable for querying for data that is in known insecure sections of
      the DNS tree.

   Not a DNS Resolver:  This is a bad address and not used anymore.

   While it would be great if all resolvers fell cleanly into one of the
   broad categories above, that is not the case.  For that reason it is



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   necessary to augment the classification with more descriptive result,
   this is done by adding the word "Partial" in front of Validator/
   DNSSEC Aware classifications, followed by sub-descriptors of what is
   not working.

   Unknown:  Failed Unknown test

   DNAME:  Failed DNAME test

   NSEC3:  Failed NSEC3 test

   TCP:  TCP not available

   SlowBig:  UDP is size limited but TCP fallback works

   NoBig:  TCP not available and UDP is size limited

   Permissive:  Passes data known to fail validation

5.  Roadblock Avoidance

   [Editors note: the goal of this document is to tie the above tests
   and aggregations to avoidance practices; however right now the "tie"
   part of this text is known to be weak.  The goal of this document is
   specifically to improve this tie as work on this document progresses]

   Once we have determined what level of support is available in the
   neighboring network, we can determine what MUST be done in order to
   effectively act as a validating resolver.  This section discusses
   some of the options available given the results from the previous
   sections.

   The general fallback approach can be described by the following
   sequence:


       If the resolver is labeled as "Validator" or "DNSSEC aware"

           Send query through this resolver and perform local
           validation on the results.

           If validation fails, try the next resolver

       Else if the resolver is labeled "Not a DNS Resolver" or
          "Non-DNSSEC capable"

           Mark it as unusable and try next resolver




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       Else if no more resolvers are configured and if direct queries
       are supported try iterating from Root

       Else return a useful error code



   While attempting resolution through a particular recursive name
   server with a particular transport method that worked, any transport-
   specific parameters MUST be remembered in order to short-circuit any
   unnecessary fallback attempts.

   Transport-specific parameters MUST also be remembered for each
   authoritative name server that is queried while performing an
   iterative mode lookup.

   Any transport settings that are remembered for a particular name
   server MUST be periodically refreshed; they should also be refreshed
   when an error is encountered as described below.

   For a stub resolver, problems with the name server MAY manifest
   themselves as the following types of error conditions:

   o  No response/error response or missing DNSSEC meta-data.

   o  Illegal Response, which prevents the validator from fetching all
      necessary records required for constructing an authentication
      chain.  This could result when referral loops are encountered,
      when any of the antecedent zone delegations are lame, when aliases
      are erroneously followed for certain RRtypes (such as SOA, DNSKEYs
      or DS records), or when resource records for certain types (e.g.
      DS) are returned from a zone that is not authoritative for such
      records.

   o  Bogus Response, when the cryptographic assertions in the
      authentication chain do not validate properly.

   For each of the above error conditions a validator MAY adopt the
   following dynamic fallback technique, preferring a particular
   approach if it is known to work for a given name server or zone from
   previous attempts.

   o  No response, error response, or missing DNSSEC meta-data

      *  Re-try with different EDNS0 sizes (4096, 1492, None)

      *  Re-try with TCP only




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      *  Perform an iterative query starting from Root if the previous
         error was returned from a lookup that had recursion enabled.

      *  Re-try using an alternative transport method, if this
         alternative method is known (configured) to be supported by the
         nameserver in question.

   o  Illegal Response

      *  Perform an iterative query starting from Root if the previous
         error was returned from a lookup that had recursion enabled.

      *  Check if any of the antecedent zones up to the closest
         configured trust anchor are provably insecure.

   o  Bogus Response

      *  Perform an iterative query starting from Root if the previous
         error was returned from a lookup that had recursion enabled.

   For each fallback technique, attempts to multiple potential name
   servers should be skewed such that the next name server is tried when
   the previous one encounters an error or a timeout is reached,
   whichever is earlier.

   The validator SHOULD remember, in its zone-specific fallback cache,
   any broken behavior identified for a particular zone for a duration
   of that zone's SOA negative TTL.

   The validator MAY place name servers that exhibit broken behavior
   into a blacklist, and bypass these name servers for all zones that
   they are authoritative for.  The validator MUST time out entries in
   this name server blacklist periodically, where this interval could be
   set to be the same as the DNSSEC BAD cache default TTL.

5.1.  Partial Resolver Usage

   It MAY be possible to use Non-DNSSEC Capable caching resolvers in
   careful ways if maximum optimization is desired.  This section
   describes some of the advanced techniques that could be used to use a
   resolver in at least a minimal way.  Most of the time this would be
   unnecessary, except in the case where none of the resolvers are fully
   compliant and thus the choices would be to use them at least
   minimally or not at all (and no caching benefits would be available).

5.1.1.  Known Insecure Lookups





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   If a resolver is Non-DNSSEC Capable but a section of the DNS tree has
   been determined to be Provably Insecure [RFC4035], then queries to
   this section of the tree MAY be sent through Non-DNSSEC Capable
   caching resolver.

5.1.2.  Partial NSEC/NSEC3 Support

   TBD

6.  Start-Up and Network Connectivity Issues

   A number of scenarios will produce either short-term or long-term
   connectivity issues with respect to DNSSEC validation.  Consider the
   following cases:

      Time Synchronization: Time synchronization problems can occure
      when a device which has been off for a period of time and the
      clock is no longer in close synchronization with "real time" or
      when a device always has clock set to the same time during start-
      up.  This will cause problems when the device needs to resolve
      their source of time synchronization, such as "ntp.example.com".

      Changing Network Properties: A newly established network
      connection MAY change state shortly after a HTTP-based pay-wall
      authentication system has been used.  This especially common in
      hotel networks, where DNSSEC, validation and even DNS are not
      functional until the user proceeds through a series of forced web
      pages used to enable their network.  The tests in
      Section Section 3 will produce very different results before and
      after the network authorization has succeeded.  APIs exist on many
      operating systems to detect initial network device status changes,
      such as right after DHCP has finished, but few (none?) exist to
      detect that authentication through a pay-wall has succeeded.

   There are only two choices when situations like this happen:

      Continue to perform DNSSEC processing, which will likely result in
      all DNS requests failing.  This is the most secure route, but
      causes the most operational grief for users.

      Turn off DNSSEC support until the network proves to be usable.
      This allows the user to continue using the network, at the
      sacrifice of security.  It also allows for a denial of security-
      service attack if a man-in-the-middle can convince a device that
      DNSSEC is impossible.

6.1.  What To Do




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   TBD

7.  IANA Considerations

   No IANA actions are require to support this document

8.  Security Considerations

   This document discusses problems that may occur while deploying the
   secure DNSSEC protocol and what mitigation's can be used to help
   detect and mitigate these problems.  Following these suggestions will
   result in a more secure DNSSEC operational environment than if DNSSEC
   was simply disabled when it fails to perform as expected.

9.  Acknowledgments

   Multiple lessons learned from multiple implementations led to the
   development of this document, including (in alphabetical order)
   DNSSEC-Tools' DNSSEC-Check, DNSSEC_Resolver_Check, dnssec-trigger,
   FCC_Grade.

   The following people contributed to portions of this document in some
   fashion: ....

10.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, March 2005.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC5155]  Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS
              Security (DNSSEC) Hashed Authenticated Denial of
              Existence", RFC 5155, March 2008.

Authors' Addresses









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   Wes Hardaker
   Parsons
   P.O. Box 382
   Davis, CA  95617
   US

   Email: hardaker@tislabs.com


   Olafur Gudmundsson
   Shinkuro Inc.
   4922 Fairmont Av, Suite 250
   Bethesda, MD  20814
   USA

   Email: ogud@ogud.com


   Suresh Krishnaswamy
   Parsons
   7110 Samuel Morse Dr
   Columbia, MD  21046
   US

   Email: suresh@tislabs.com


























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