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PANA Discussion and Open Issues (draft-ietf-pana-pana-01.txt)

PANA Discussion and Open Issues (draft-ietf-pana-pana-01.txt). Dan Forsberg, Yoshihiro Ohba, Basavaraj Patil, Hannes Tschofenig, Alper Yegin. Open Issue List (ordered by importance) http://www.danforsberg.info:8080/pana-issues/. Issue 9: Message Format.

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PANA Discussion and Open Issues (draft-ietf-pana-pana-01.txt)

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  1. PANA Discussion and Open Issues(draft-ietf-pana-pana-01.txt) Dan Forsberg, Yoshihiro Ohba, Basavaraj Patil, Hannes Tschofenig, Alper Yegin IETF 57 PANA WG

  2. Open Issue List (ordered by importance)http://www.danforsberg.info:8080/pana-issues/ IETF57 PANA WG

  3. Issue 9: Message Format • Issue: Message format Not defined in -00 draft • Proposed resolution: -01 draft contains format • Diameter-like message format: header + AVPs • No application-Identifier (as in Diameter) in PANA message header • Hop-by-hop and End-to-end identifiers (that exist in Diameter header) are replaced with sequence numbers in PANA header • The same AVP format as Diameter AVPs • Changes to message names (from 00 to 01) IETF57 PANA WG

  4. PANA Header Format 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R r r r F r r r| Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Transmitted Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Received Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVPs ... +-+-+-+-+-+-+-+-+-+-+-+-+- • Flags • ‘R’-flag: Indicates whether the message is a request. • ‘F’-flag: Indicates if this was the final authentication from sender's perspective. Used in PANA-Bind-Request/Answer messages. IETF57 PANA WG

  5. PANA AVP Format 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AVP Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V M r r r r r r| AVP Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor-Id (opt) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Data ... +-+-+-+-+-+-+-+-+ • Flags • ‘V’-flag: Indicates whether this AVP is a vendor-specific AVP. • ‘M’-flag: Indicates whether this AVP is mandatory supported AVP. IETF57 PANA WG

  6. List of Changes in Message Names IETF57 PANA WG

  7. List of AVPs • Cookie AVP • Device-Id AVP • EAP-Payload AVP • MAC AVP • Protection-Capability AVP • Result-Code AVP • Session-Id AVP • Session-Lifetime AVP • Termination-Cause AVP IETF57 PANA WG

  8. Issue 4,5,16: Device Identifier • Issues: • There is a scenario where the DI needs to be updated • There may be a case where both MAC and IP addresses are used at the same time as a DI • There may be a case where multiple IP addresses are used as a DI IETF57 PANA WG

  9. Updating Device Identifier • Possible scenario: • PaC performs PANA using unspecified IP address and establishes MSK • The MAC address is used as the DI and bound to MSK, or DI can be null if it is enough to bind Session-ID to the MSK • PaC obtains an IP address (via DHCP, etc.) • PaC and EP bootstraps IKE from the MSK • The MSK needs to be bound to the IP address • Proposed Resolution: DI update can be done in PANA-Reauth exchange • PANA-Reauth-{Request,Answer} message can carry Device-ID AVP IETF57 PANA WG

  10. Using both MAC and IP addressesat the same time as DI • This is the case where both L2 and L3 ciphering are bootstrapped from PANA • Insider attackers can spoof either IP or MAC address of data packets without both ciphering • Resolution? • Support either MAC or IP addresses as a DI, and not both addresses at the same time • Support both addresses at the same time as well • Note: neither A nor B solves IP address ownership problem which is solved only by SEND IETF57 PANA WG

  11. Multiple IP Addresses as DI • PaC can have multiple IP addresses on the same interface • Link local address, global addresses, etc. • PaC does not specify all IP addresses as PANA DI if: • Only L2 ciphering is used, or • One (link-local) address is used as DI and the local end-point of IPsec tunnel, and other addresses are configured inside the tunnel • Multi-interfaced PaC can perform separate PANA per interface • Resolution? • Is this sufficient? • Should we list all IP addresses as DI and bind to PANA session (in order to solve IP address authorization problem)? IETF57 PANA WG

  12. Issue 6: Session Identifier • Issue: How can a PANA session be identified? • Discussion: • Can a DI be used as a session identifier ? • A separate session ID is useful when updating DI • Such a session ID can be used for mobility handling • Proposed resolution: A Session-Id AVP is defined • The Session-Id AVP MAY use Diameter message formatting IETF57 PANA WG

  13. Issue 3: PANA SA • Issue: What is PANA SA? How it is created? • Proposed resolution: Added a new section 4.1.5 “PANA Security Association IETF57 PANA WG

  14. Definition of PANA SA • A PANA SA is created when EAP authentication succeeds with a creation of MSK (Master Session Key) • When two EAP authentications are performed in PANA (i.e., ISP/NAP separation), two MSKs may be created • PANA SA is bound to the first established MSK, not to both MSKs • PANA_MAC_Key = The first N-bit of HMAC_SHA1(MSK, ISN_pac|ISN_paa|Session-ID) (N=128 and 160, if MAC algorithm is HMAC-MD5 and HMAC-SHA1, respectively) IETF57 PANA WG

  15. Issue 8: Refresh Interval Negotiation • Issue: What parameter should PAA communicate to PaC to perform re-authentication? • There are two types of re-authentication: (I) EAP-based re-auth. and (II) fast re-auth. via PANA-Reauth exchange • Possible parameters: • Session lifetime for EAP-based reauthentication • Interval for PANA-Reauth exchange • Mobile IP supports refresh interval negotiation while 802.1X and IKEv2 do not • Resolution? • Should session lifetime be carried? • When carried, it is indicated by the PAA as a non-negotiable, informational parameter • Should PANA-Reauth interval be carried? IETF57 PANA WG

  16. Issue 11: New PANA Client Notification • Issue: Should PANA define message format for event notification from EP to PAA? • Proposed resolution: Added a new section 4.10 “Event Notification” • Event notification message can be one of the messages provided by the PAA-EP protocol or can be a “PANA-Discover” message IETF57 PANA WG

  17. Issue 7: Mobility Handling • Issue: In case of mobility it is useful to move PANA session state from one PAA to another forperformance reasons • Proposed resolution: Added a new section 4.9 “Mobility Handling” • Fast re-authentication can be used instead of EAP-based re-authentication when PANA session state is available on the new PAA • Assumes the state can be brought to the new PAA (e.g., by Seamoby Context Transfer Protocol) IETF57 PANA WG

  18. Mobility Handling Example Old PAA New PAA PaC PANA-Discover PANA-Start-Request[Cookie] Context Transfer (Session-Id, MSK, etc) PANA-Start-Answer[Cookie, Session-Id] PANA-Reauth-Request[Session-Id,MAC] PANA-Reauth-Answer[Session-Id,MAC] IETF57 PANA WG

  19. Issue 15: Cookie vs. Puzzle • Issue: The cookie mechanism defined in discovery and handshake phase might not be effective for on-link attackers • Another mechanism based on ‘Puzzle’ is proposed • The PAA sends a challenge that does not need a shared secret for PaC to respond but need some calculation on PaC • Introducing another DoS attack by sending ‘difficult-to-solve’ puzzle to PaC • Proposed Resolution: • Use Cookie by default, with allowing Puzzle to be specified in a separate document if needed IETF57 PANA WG

  20. Issue 18,19: Values for Termination-Cause and Result-Code AVPs • Issue: AVP values need to be defined for Termination-Cause and Result-Code AVPs • Proposed resolution: Values are defined in sections 9.4.6 and 9.4.7 IETF57 PANA WG

  21. Issue 1,2: Capability Negotiation and Downgrading Protection • Issue: Does PANA need to support capability negotiation • Capability of L2/L3 ciphers • Discussion: • Capability negotiation outside EAP can be a place for downgrading attack • Proposed resolution • Support capability indication (i.e., non-negotiable) from PAA • Protection-Capability AVP in protected PANA-Bind-Request/Answer exchange is used for this purpose IETF57 PANA WG

  22. Thank you! IETF57 PANA WG

  23. Backup Slides IETF57 PANA WG

  24. Termination-Cause AVP Values IETF57 PANA WG

  25. Result-Code AVP Values IETF57 PANA WG

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