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DNSSEC Basics

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					DNSSEC Deployment WG                                Peter Koch




                          DNSSEC
                           Basics

                              Peter Koch
                              DENIC eG
                            pk@DENIC.DE



                         Luxembourg, 2005-07-12



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DNSSEC Deployment WG                                            Peter Koch




                                         Agenda

           • Why? – DNS weaknesses

           • Why, really? – . . . and when they matter

           • What can implementations do?
           • What will DNSSEC achieve?

           • How does it work?




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DNSSEC Deployment WG                                          Peter Koch




                                   DNS Weatures

           • Millions of Interacting Components

           • No Cryptographic Security
           • Lightweight, UDP based
              No Connections

           • 16bit ID space
              Guessing, Flooding, Birthday Attacks

           • Caching, Additional Section Processing
              Kashpureff Style Attacks



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DNSSEC Deployment WG                                           Peter Koch




                           Today’s Implementations

           • Ignore much Additional Information

           • Apply Credibility Heuristics to DNS Answers
           • Truly Randomize IDs and Ports

           • Allow for Restricted Recursion
           • are Strengthened but Not Immune




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DNSSEC Deployment WG                                              Peter Koch




                            The Main DNSSEC Benefits

           • Data Origin Authentication
                – Data Forgery will be detected
           • Data Integrity
                – Data Modification will be detected




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DNSSEC Deployment WG                                                     Peter Koch




                         How are the Benefits Achieved?

           • Industrial Grade Public Key Signatures
           • No PKI needed, leverages on DNS Scalability and Pervasion

           • Vendor Independent Technology (IETF Proposed Standard)
              (RFCs 4033, 4034, 4035, March 2005)
           • Per Zone Key Pair

           • Chain of Trust through the well known Delegation Process




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DNSSEC Deployment WG                                            Peter Koch




                              Some DNSSEC Details

           • Authenticates DNS Resource Record Sets
              (All addresses of www.example.org)

           • . . . as well as the Absence of Records or Names
              (rss.example.org does not exist)
           • Introduces four New DNS Record Types

           • Full RFC 4033-35 support in BIND 9.3 and NSD 2




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DNSSEC Deployment WG                                               Peter Koch




                                  Almost Gory Details

           • Zone Maintainer generates per Zone Key Pair

           • Public Key is Published through DNS
           • Private Key is used to sign . . .
                – all Records
                – all Gaps between Names
                – DS Records for Delegated Child Zones
           • Signatures are piggy backed on DNS responses

           • . . . if querying client signaled DNSSEC capability



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DNSSEC Deployment WG                                          Peter Koch




                                     Registries’ Tasks

           • Have DNSSEC Capable Name Servers for the TLD
           • Have Policies in Place

           • Registrar Interaction

           • Key Handling
           • Signatures over DS Records




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DNSSEC Deployment WG                                                            Peter Koch




                            The main DNSSEC costs


                             End User   Domain Holder      ISP   Registrar   Registry
              CPU cycles        X                          X                    X
           Key Management      (X)           (X)           X       (X)         (X)
                Expertise                                  X        X           X




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DNSSEC Deployment WG                                                                      Peter Koch



                          Is DNSSEC Really Necessary?

           • We do not fuel panic, there’s no guarantee for attack tomorrow
           • . . . However, spoofing tools are readily available
           • Most target the local recursive server
           • . . . but some are more sophisticated
           • Even sophisticated implementations with enough random cannot
             protect against spoofing
           • This is not only about bugs, it is about a protocol inherent vulnerability
           • There are too many components that need to be configured correctly
           • Currently, the incentive is low
           • . . . since, e.g. phishing is much easier

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DNSSEC Deployment WG                                                              Peter Koch




                                  Where DNSSEC fits

           • DNSSEC is not a panacea

           • . . . but a Piece of the Security Puzzle
           • You know, we have Safety Belts and Airbags and ESP and Guard Rails
             and . . .

           • https is Not Enough
           • . . . and Not Always Applicable




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DNSSEC Deployment WG                                                              Peter Koch




                                  Time to Say Hello

           • DNSSEC needs preparation
           • Can’t just Ship a Patch

           • Needs Interaction with Registrars and/or Customers (DNS Zone
             Maintainers)
           • So, when attacks start next year, you better start preparing today




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DNSSEC Deployment WG                                                               Peter Koch




                                Why we, why now?

           • Honestly, we are trying to be responsible

           • Initiative for security measures has always come from the outside
           • Ban of cleartext passwords (in protocols) needed a strong word from
             the IESG

           • Secure DNS Tree needs Signed TLDs (and Root!)
           • Helps Securing the Underlying Technical Infrastructure




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DNSSEC Deployment WG                      Peter Koch




                         ?–!




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Description: DNS Security Extensions, is a series provided by the IETF DNS security authentication mechanisms (refer to RFC2535). It provides a source of identification and data integrity of the extensions, but do not guarantee availability, encryption, and proven domain name does not exist.