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Link-local security

Link-local security. J.W. Atwood, S. Islam, S. Maziar PIM Working Group 2008/11/18 bill@cse.concordia.ca. draft-ietf-pim-sm-linklocal-05. Minor changes Introduction sets up the environment Notes possibility of GSAKMP for automated key management Some housekeeping New Stuff

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Link-local security

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  1. Link-local security J.W. Atwood, S. Islam, S. Maziar PIM Working Group 2008/11/18 bill@cse.concordia.ca

  2. draft-ietf-pim-sm-linklocal-05 • Minor changes • Introduction sets up the environment • Notes possibility of GSAKMP for automated key management • Some housekeeping • New Stuff • Section on “Rekeying” (copied from 4552)

  3. Recent activity • Attempts to get help on the “environment” problem • Distributed key servers • Router identification • Realization that this draft is (almost) independent of those issues

  4. Setting the Environment • Router identification • Controlling keys • Controlling adjacency • Usefulness of distributed keyservers

  5. Router Identity • A mechanism exists to give each router an identity • Unique within an administrative region • PKI, HIP, etc. • See “Router Identification Problem Statement” at IETF-71

  6. Controlling keys and adjacency • GC/KS exists • Assign DEKs and SAIs • GC can answer the question, “is this router a legitimate neighbor for me?” • A “distributed key server” model may be appropriate • See “Distributed Keyservers” at IETF-71

  7. Examples • Two “end” cases provide the examples • One key, one SA for the entire administrative region • One key, one SA for each speaking router

  8. A walk through the draft • RFC 4601 is based on the new AH, and mandates authentication using AH • We draw heavily from RFC 4552 • Specify mandatory authentication and optional confidentiality • Keying • Require manual keying • Provide means of support for automatic keying

  9. Transport vs. Tunnel mode • Two routers are acting as hosts • MUST support transport mode • MAY support tunnel mode

  10. Authentication & Confidentiality • MUST support authentication • MUST support ESP • MAY support AH • SHOULD support confidentiality • MUST use ESP

  11. IPsec requirements • Transport mode • Multiple SPDs • Selectors • Interface ID tagging • Manual key support • No stream ciphers • IP encapsulation

  12. Key management • MUST support manual keying • Do not preclude the use of IKE or GSAKMP to establish keys

  13. Manual Key Management • Manual configuration at boot-up • SAD entries • SPD entries

  14. Automated Key Management • Cannot use IKE • Could use GDOI • Could use GSAKMP

  15. Communication Patterns • Each “speaker” represents a small group • All are sending on the same destination address • New rules in IPsec allow using sender address and interface ID tag to differentiate

  16. Key Server Models • Go to regional KS for keys • Go to local KS (the speaking router) for keys • (allows continuing when path to regional KS is broken)

  17. Neighbor Relationships • Managed by regional GC • Out of scope for this document

  18. Number of Sas • Optional: one SA for each neighbor plus one for outgoing • Mandatory: one SA for all neighbors and one for outgoing

  19. Rekeying • Procedure for doing it • Configurable KeyRolloverInterval • Rekeying Interval • Manual: 90 days • Automatic: Will be specified by the key server document

  20. IPsec Protection Barrier and GSPD • Manual Keying • SAD entries • SPD entries

  21. ..2 • Automatic Keying • SAD entries (created by the automatic procedure) • GSPD entries • Configured “send only” • Triggered by the automatic procedure • PAD entries • Filled by adjacency management • Out of scope for document

  22. Security Association Lookup • Multicast lookup uses • Sender address (not unique because of link-local addresses) • Interface ID tag • SPI

  23. Activating Anti-replay • Only recommended for automatic keying • Keep sequence number per SA • Keep SA per sender

  24. SAD per interface • 4601 suggests it may be desirable • 4301 deprecates SAD per interface • Replaced with interface ID tags for lookup

  25. Extended Sequence Number • Suggested for use with manual keying

  26. Security Considerations • Limitations of manual keys • Impersonation in single-key group • Pointers to • 4593 (Generic Threats to Routing Protocols) • 5294 (Specific threats to PIM-SM) • 4601 (PIM-SM)

  27. Plans • Tidy up a few housekeeping issues • Listen carefully for feedback during and after this meeting • Ask for WGLC, based on the next version of the draft

  28. Questions?

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