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RFC 4740

 
 
 

Diameter Session Initiation Protocol (SIP) Application

Part 4 of 4, p. 59 to 72
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10.  New Values for Existing AVPs

   This section defines new values that the Diameter SIP application
   extends to already existing AVPs.

10.1.  Extension to the Result-Code AVP Values

   The Result-Code AVP is already defined in RFC 3588 [RFC3588].  In
   addition to the values already defined in RFC 3588 [RFC3588], the
   Diameter SIP application defines the following new Result-Code AVP
   values:

10.1.1.  Success Result-Code AVP Values

   A Diameter peer uses Result-Code AVP values that fall into the
   success category to inform the remote peer that a request has been
   successfully completed.

   o  DIAMETER_FIRST_REGISTRATION 2003
      The user was not previously registered.  The Diameter server has
      now authorized the registration.

   o  DIAMETER_SUBSEQUENT_REGISTRATION 2004
      The user is already registered.  The Diameter server has now
      authorized the re-registration.

   o  DIAMETER_UNREGISTERED_SERVICE 2005
      The user is not currently registered, but the requested service
      can still be granted to the user.

   o  DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED 2006
      The request operation was successfully processed.  The Diameter
      server does not keep a record of the SIP server address assigned
      to the user.

   o  DIAMETER_SERVER_SELECTION 2007
      The Diameter server has authorized the registration.  The user has
      already been assigned a SIP server, but it may be necessary to
      select a new SIP server for the user.

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   o  DIAMETER_SUCCESS_AUTH_SENT_SERVER_NOT_STORED 2008
      The requested operation was successfully executed.  The Diameter
      server is sending a number of authentication credentials in the
      answer message.  The Diameter server does not keep a record of the
      SIP server.

10.1.2.  Transient Failures Result-Code AVP Values

   A Diameter peer uses a Result-Code AVP value that falls in the
   transient failures category to inform the remote peer that a request
   could not be satisfied at the time it was received, but it MAY be
   satisfied by the Diameter peer in the future.

   o  DIAMETER_USER_NAME_REQUIRED 4013
      The Diameter request did not contain a User-Name AVP, which is
      required to complete the transaction.  The Diameter peer MAY
      include a User-Name AVP and attempt the request again.

10.1.3.  Permanent Failures Result-Code AVP Values

   A Diameter peer uses a Result-Code AVP value that falls into the
   permanent failure category to inform the remote peer that the request
   failed and should not be attempted again.

   o  DIAMETER_ERROR_USER_UNKNOWN 5032
      The SIP-AOR AVP value does not belong to a known user in this
      realm.

   o  DIAMETER_ERROR_IDENTITIES_DONT_MATCH 5033
      The value in one of the SIP-AOR AVPs is not allocated to the user
      specified in the User-Name AVP.

   o  DIAMETER_ERROR_IDENTITY_NOT_REGISTERED 5034
      A query for location information is received for a SIP AOR that
      has not been registered before.  The user to which this identity
      belongs cannot be given service in this situation.

   o  DIAMETER_ERROR_ROAMING_NOT_ALLOWED 5035
      The user is not allowed to roam to the visited network.

   o  DIAMETER_ERROR_IDENTITY_ALREADY_REGISTERED 5036
      The identity being registered has already been assigned a server
      and the registration status does not allow that it is overwritten.

   o  DIAMETER_ERROR_AUTH_SCHEME_NOT_SUPPORTED 5037
      The authentication scheme indicated in an authentication request
      is not supported.

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   o  DIAMETER_ERROR_IN_ASSIGNMENT_TYPE 5038
      The SIP server address sent in the SIP-Server-URI AVP value of the
      Diameter Server-Assignment-Request (SAR) command is the same SIP
      server address that is currently assigned to the user name, but
      the SIP-Server-Assignment-Type AVP is not allowed.  For example,
      the user is registered and the Server-Assignment-Request indicates
      the assignment for an unregistered user.

   o  DIAMETER_ERROR_TOO_MUCH_DATA 5039
      The Diameter peer in the SIP server receives more data than it can
      accept.  The SIP server cannot overwrite the already stored data.

   o  DIAMETER_ERROR_NOT SUPPORTED_USER_DATA 5040
      The SIP server informs the Diameter server that the received
      subscription data contained information that was not recognized or
      supported.

11.  Authentication Details

   Authenticating a user can occur through various mechanisms.
   Currently HTTP Digest authentication is supported.  The actual
   authentication is performed in either the SIP server or the Diameter
   server.

   If the Diameter server wants to assure that authentication will take
   place in the Diameter server (as opposed to a delegated
   authentication taking place in the SIP server), it MUST NOT include a
   Digest-HA1 AVP (part of the grouped SIP-Authenticate AVP, which in
   turn is part of the SIP-Auth-Data-Item AVP) in a MAA message.  The
   Diameter server MAY include a pre-calculated Digest-HA1 AVP in the
   MAA message if it wants to delegate authentication of the user to the
   SIP server.

   Note that on systems where the SIP User Agent is using HTTP Digest
   authentication [RFC2617] inside of Transport Layer Security (TLS)
   [RFC4346], where only the SIP proxy server has a certificate,
   delegating authentication to the SIP server (by making Digest-HA1
   available to the SIP server) might reduce the load on the Diameter
   server.

   When requesting authentication, the Diameter client indicates in the
   SIP-Number-Auth-Items AVP value of a Diameter MAR message how many
   authentication credentials are being requested.  In the Diameter MAA
   message, the Diameter server MAY include more than one
   SIP-Auth-Data-Item AVP, but it is only useful for the Diameter client
   if the Digest-QoP AVP was set to 'auth-int' (in the MAR message), and
   if future authentications will have the same realm.  When including
   more than one SIP-Auth-Data-Item AVP, the Diameter server SHOULD

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   indicate how many instances of SIP-Auth-Data-Item AVPs are present
   with the SIP-Number-Auth-Items AVP.  This number may be different
   from the one requested in the Diameter MAR message.  If multiple
   SIP-Auth-Data-Item AVPs are present, and their ordering is
   significant, the Diameter server MUST include a SIP-Item-Number AVP
   in each grouping to indicate the order.  The
   SIP-Authentication-Scheme AVP indicates "Digest" and the
   SIP-Authenticate AVP contains data (typically a challenge of some
   kind) that the user can use for her authentication.  The grouped
   SIP-Authorization AVP contains the AVPs that conform to the response
   expected from the user.

   If the Diameter server performs the authentication of the user, the
   Diameter MAR message that the Diameter client sends to the Diameter
   server MUST include all the authentication credentials supplied by
   the SIP UA (there might be more than one credential, e.g., different
   realms, authentication of proxies, etc.).  Each credential is
   inserted in a grouped SIP-Authorization AVP (part of the grouped
   SIP-Auth-Data-Item AVP).  The Diameter client MUST insert a
   SIP-Number-Auth-Items AVP with the value set to the number of
   credentials enclosed.  If necessary, the Digest-Entity-Body-Hash AVP
   will contain a hash of the body, needed to perform the
   authentication.  If the authentication is successful, the Diameter
   MAA message will contain a Result-Code AVP indicating success, and if
   necessary, the Diameter server MAY include one or more
   SIP-Auth-Data-Item AVPs to provide further authentication credentials
   to the SIP server.  If the authentication is unsuccessful due to
   missing credentials, the Diameter MAA message will include a
   SIP-Auth-Data-Item AVP with the SIP-Authentication-Scheme and
   SIP-Authenticate AVPs containing data (typically a challenge of some
   kind) that the user can use to authenticate itself.

   There are situations where a SIP request traverses several proxies,
   and each of the proxies requests to authenticate the SIP UA.  In this
   situation, it is a valid scenario that a SIP request received at a
   SIP server contains several sets of credentials.  The 'realm'
   directive in HTTP is the key that the Diameter client can use to
   determine which credential is applicable.  Also, none of the realms
   may be of interest to the Diameter client, in which case the Diameter
   client MUST consider that no credentials (of interest) were sent.  In
   any case, a Diameter client MUST send zero or exactly one credential
   to the Diameter server.  The Diameter client MUST choose the
   credential based on the 'realm' directive in the
   Authorization/Proxy-Authorization header field, and it MUST match the
   realm of the Diameter client.

   It must be noted that nonces are always generated in the Diameter
   server.

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12.  Migration from RADIUS

   RADIUS offers support for HTTP Digest authentication in the RADIUS
   Extension for Digest Authentication [RFC4590].  A number of AVPs (the
   Digest-* AVPs) of this Diameter SIP application are imported from the
   RADIUS attributes namespace, thus making the migration from RADIUS to
   Diameter smooth.

   Note that the RADIUS Extension for Digest Authentication [RFC4590]
   provides a more limited scope than this Diameter SIP application.
   Specifically, the RADIUS extension for Digest Authentication merely
   provides support for HTTP Digest authentication, whereas the Diameter
   SIP application provides support for user location, profile
   downloading and update, etc.

   The following sections discuss several configurations in which a
   gateway translates RADIUS to Diameter and vice versa.

12.1.  Gateway from RADIUS Client to Diameter Server

   The gateway maps Access-Request messages to MAR request.  If a RADIUS
   Access-Request message contains at least one Digest-* attribute, the
   gateway maps all Digest-* attributes to the AVPs of a Diameter
   SIP-Authorization AVP, constructs a MAR message, and sends it to the
   Diameter server.  If the RADIUS Access-Request message does not
   contain any Digest-* attribute, then the RADIUS client does not want
   to apply HTTP Digest authentication, in which case, actions at the
   gateway are outside the scope of this document.

   The Diameter server responds with a MAA message.  If the MAA message
   contains a Result-Code AVP set to the value DIAMETER_MULTI_ROUND_AUTH
   and contains challenge parameters in a SIP-Authenticate AVP, then the
   gateway translates the AVPs of SIP-Authenticate AVP and puts the
   resulting RADIUS attributes into an Access-Challenge message.  It
   sends the Access-Challenge message to the RADIUS client.

   If the MAA message contains a SIP-Authentication-Info and a
   Digest-Response AVP, the gateway converts these AVPs to the
   corresponding RADIUS attributes and constructs a RADIUS message.  If
   the Result-Code AVP is DIAMETER_SUCCESS, an Access-Accept is sent.
   In all other cases, an Access-Reject is sent.

12.2.  Gateway from Diameter Client to RADIUS Server

   The Diameter client sends a Diameter MAR message to the gateway.  If
   the MAR message does not contain SIP-Auth-Data-Item AVPs, the gateway
   constructs an Access-Request message and maps the SIP-AOR and
   SIP-Method AVPs to RADIUS attributes.  The gateway sends the

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   Access-Request message to the RADIUS server, which will respond with
   an Access-Challenge.  The gateway creates a MAA message with a
   Result-Code AVP set to DIAMETER_MULTI_ROUND_AUTH and maps the
   Digest-* attributes to Diameter AVPs in a SIP-Authenticate AVP.  The
   gateway sends the resulting MAA to the Diameter client, which will
   respond with a new MAR.

   The gateway checks the SIP-Auth-Data-Item AVPs of this MAR for an AVP
   where the Digest-Realm AVP matches the locally configured realm
   value.  It takes the AVPs from this SIP-Auth-Data-Item AVP, converts
   them into the corresponding RADIUS attributes and constructs a RADIUS
   Access-Request message.  The gateway sends the Access-Request message
   to the RADIUS server.  If the RADIUS server responds with an
   Access-Accept message, the gateway converts the RADIUS attributes to
   Diameter AVPs, constructs a MAA message with a Result-Code AVP set to
   DIAMETER_SUCCESS and sends this message to the Diameter client.  If
   the RADIUS server responds with an Access-Reject message, the gateway
   converts the RADIUS attributes to Diameter AVPs, constructs a MAA
   message with a Result-Code AVP set to
   DIAMETER_ERROR_IDENTITIES_DONT_MATCH, and sends this message to the
   Diameter client.

12.3.  Known Limitations

   As mentioned earlier, there is not a 100% match between the Diameter
   SIP application and the RADIUS Extension for Digest Authentication
   [RFC4590].  In particular, the RADIUS Extension for Digest
   Authentication [RFC4590] does not offer equivalent functionality to
   the Diameter UAR/UAA, SAR/SAA, LIR/LIA, RTR/RTA, and PPR/PPA messages
   defined by this specification.

13.  IANA Considerations

   This document serves as IANA registration request for a number of
   items that should be registered in the AAA parameters registry.

13.1.  Application Identifier

   This document defines a standards-track Application-ID that falls
   into the Application Identifier standards-track address space defined
   by RFC 3588 [RFC3588] Section 11.3.  This Application-ID has been
   registered in the Application IDs sub-registry of the AAA parameters
   registry with the following data:

    ID values     Name                                Reference
   -----------    ------------------------            ---------
           6      Diameter Session Initiation         RFC 4740
                  Protocol (SIP) Application

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13.2.  Command Codes

   This document defines new standard commands whose Command Codes are
   to be allocated within the standard permanent Command Codes address
   space defined in RFC 3588 [RFC3588] Section 11.2.1.  These command
   codes should be registered in the Command Codes sub-registry of the
   AAA parameters registry.

   Table 1 in Section 8 contains the detailed list of Command Code names
   and values that are part of this Diameter application.

13.3.  AVP Codes

   This document defines new standard AVPs, whose AVP Codes are to be
   allocated within the AVP Codes address space defined in RFC 3588
   [RFC3588] Section 11.4.  These AVP codes have been registered in the
   AVP Codes sub-registry of the AAA parameters registry.

   Table 2 in Section 9 contains the detailed list of AVP names and AVP
   codes that are part of this Diameter application.

13.4.  Additional Values for the Result-Code AVP Value

   This document defines new standard Result-Code AVP values to be
   allocated within the Result-Code AVP address space defined in RFC
   3588 [RFC3588] Section 14.4.1.  These values are listed in the
   Result-Code AVP values section of the AVP Specific Values
   sub-registry of the AAA parameters registry.

   Section 10.1.1 lists the new Result-Code AVP values that fall into
   the success category, according to RFC 3588 [RFC3588] Section 7.1.2.

   Section 10.1.2 lists the new Result-Code AVP values that fall into
   the transient failures category, according to RFC 3588 [RFC3588]
   Section 7.1.4.

   Section 10.1.3 lists the new Result-Code AVP values that fall into
   the permanent failures category, according to RFC 3588 [RFC3588]
   Section 7.1.5.

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13.5.  Creation of the SIP-Server-Assignment-Type Section in the AAA
       Registry

   This document defines a new SIP-Server-Assignment-Type AVP (see
   Section 9.4).  This AVP is of type Enumerated.  We define an initial
   set of values that should be registered by IANA.  IANA should create
   a new "SIP-Sever-Assignment-Type AVP values" section under the AVP
   Specific Values sub-registry of the AAA parameters registry.  The
   initial list of values is listed in Section 9.4.

13.6.  Creation of the SIP-Authentication-Scheme Section in the AAA
       Registry

   This document defines a new SIP-Authentication-Scheme AVP (see
   Section 9.5.1).  This AVP is of type Enumerated.  We currently define
   a single value that should be registered by IANA.  IANA should create
   a new "SIP-Authentication-Scheme AVP values" section under the AVP
   Specific Values sub-registry of the AAA parameters registry.  The
   initial list of values is included in Section 9.5.1.

13.7.  Creation of the SIP-Reason-Code Section in the AAA Registry

   This document defines a new SIP-Reason-Code AVP (see Section 9.7.1).
   This AVP is of type Enumerated.  We define an initial set of values
   that should be registered by IANA.  IANA should create a new
   "SIP-Reason-Code AVP values" section under the AVP Specific Values
   sub-registry of the AAA parameters registry.  The initial list of
   values is listed in Section 9.7.1.

13.8.  Creation of the SIP-User-Authorization-Type Section in the AAA
       Registry

   This document defines a new SIP-User-Authorization-Type AVP (see
   Section 9.10).  This AVP is of type Enumerated.  We define an initial
   set of values that should be registered by IANA.  IANA should create
   a new "SIP-User-Authorization-Type AVP values" section under the AVP
   Specific Values sub-registry of the AAA parameters registry.  The
   initial list of values is listed in Section 9.10.

13.9.  Creation of the SIP-User-Data-Already-Available Section in the
       AAA Registry

   This document defines a new SIP-User-Data-Already-Available AVP (see
   Section 9.13).  This AVP is of type Enumerated.  We define an initial
   set of values which should be registered by IANA.  IANA should create
   a new "SIP-User-Data-Already-Available AVP values" section under the
   AVP Specific Values sub-registry of the AAA parameters registry.  The
   initial list of values is listed in Section 9.13.

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14.  Security Considerations

   This memo does not describe a stand-alone protocol, but a particular
   application for the Diameter protocol [RFC3588].  Consequently, all
   the security considerations applicable to Diameter automatically
   apply to this memo.  In particular, Section 13 of RFC 3588 applies to
   this memo.

   This Diameter SIP application allows a Diameter client to use the
   properties of HTTP Digest authentication [RFC2617] by evaluating or
   sending to the Diameter server the credentials supplied by a user.
   The discussion of HTTP Digest authentication in Section 4 of RFC 2617
   [RFC2617] is also applicable to this memo.

   This Diameter SIP application also allows a Diameter client to use
   the properties of HTTP Digest authentication using AKA [RFC3310] by
   evaluating or sending to the Diameter server the credentials supplied
   by a user.  Section 5 of RFC 3310 [RFC3310] is also applicable to
   this memo.

14.1.  Final Authentication Check in the Diameter Client/SIP Server

   The Diameter SIP application can be configured to operate in a
   scenario where the final authentication check is performed in the
   Diameter client (SIP server).  There are a number of security
   considerations associated to it; all of them are consequences of the
   requirement to transfer H(A1) from the Diameter server to the
   Diameter client:

   o  Both Diameter client and server must trust each other, such as
      when both client and server belong to the same administrative
      domain.

   o  To avoid eavesdroppers, the transport protocol between the
      Diameter client and server MUST be secured.  RFC 3588 [RFC3588]
      specifies TLS [RFC4346] and IPsec as possible transport protection
      mechanisms for Diameter.

   Due to these security considerations, it is RECOMMENDED to configure
   the Diameter SIP application to operate in the mode where the final
   authentication check is performed in the Diameter server.

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15.  Contributors

   The authors would like to thank the following contributors who made
   substantial contributions to this work:

          Pete McCann           Lucent

          Jaakko Rajaniemi      Nokia

   Wolfgang Beck (Deutsche Telekom AG) provided the text in Section 12,
   "Migration from RADIUS".

16.  Acknowledgements

   The authors would like to thank Tony Johansson and Kevin Purser for
   their invaluable contribution to the start-up of this application and
   the continuous progress.  The authors would like to thank Daniel
   Warren, Jayshree Bharatia, Kuntal Chowdhury, Jari Arkko, Avi Lior,
   Wolfgang Beck, Ulrich Wiehe, Cullen Jennings, Anu Leinonen, Glen
   Zorn, German Blanco, Mikko Aittola, Bert Wijnen, and Sam Hartman for
   their reviews and valuable comments.

   The Diameter SIP application is based on the Diameter application for
   the Cx interface of the 3GPP IP Multimedia Subsystem [3GPP.29.229].
   The authors would like to thank 3GPP Working Group CN4 for this work.

17.  References

17.1.  Normative References

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

   [RFC2617]      Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence,
                  S., Leach, P., Luotonen, A., and L. Stewart, "HTTP
                  Authentication: Basic and Digest Access
                  Authentication", RFC 2617, June 1999.

   [RFC3261]      Rosenberg, J., Schulzrinne, H., Camarillo, G.,
                  Johnston, A., Peterson, J., Sparks, R., Handley, M.,
                  and E.  Schooler, "SIP: Session Initiation Protocol",
                  RFC 3261, June 2002.

   [RFC3310]      Niemi, A., Arkko, J., and V. Torvinen, "Hypertext
                  Transfer Protocol (HTTP) Digest Authentication Using
                  Authentication and Key Agreement (AKA)", RFC 3310,
                  September 2002.

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   [RFC3588]      Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and
                  J.  Arkko, "Diameter Base Protocol", RFC 3588,
                  September 2003.

   [RFC4590]      Sterman, B., Sadolevsky, D., Schwartz, D., Williams,
                  D., and W. Beck, "RADIUS Extension for Digest
                  Authentication", RFC 4590, July 2006.

17.2.  Informative References

   [RFC4346]      Dierks, T. and E. Rescorla, "The Transport Layer
                  Security (TLS) Protocol Version 1.1", RFC 4346, April
                  2006.

   [RFC3263]      Rosenberg, J. and H. Schulzrinne, "Session Initiation
                  Protocol (SIP): Locating SIP Servers", RFC 3263,
                  June 2002.

   [RFC3680]      Rosenberg, J., "A Session Initiation Protocol (SIP)
                  Event Package for Registrations", RFC 3680,
                  March 2004.

   [RFC3880]      Lennox, J., Wu, X., and H. Schulzrinne, "Call
                  Processing Language (CPL): A Language for User Control
                  of Internet Telephony Services", RFC 3880,
                  October 2004.

   [RFC4004]      Calhoun, P., Johansson, T., Perkins, C., Hiller, T.,
                  and P. McCann, "Diameter Mobile IPv4 Application",
                  RFC 4004, August 2005.

   [RFC4005]      Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
                  "Diameter Network Access Server Application",
                  RFC 4005, August 2005.

   [RFC4006]      Hakala, H., Mattila, L., Koskinen, J-P., Stura, M.,
                  and J. Loughney, "Diameter Credit-Control
                  Application", RFC 4006, August 2005.

   [3GPP.29.229]  3GPP, "Cx and Dx interfaces based on the Diameter
                  protocol; Protocol details", 3GPP TS 29.229 5.12.0,
                  June 2006.

   [JSR-000116]   Java Community Process, "SIP Servlet API Specification
                  1.0 Final Release", JSR 000116, March 2003.

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Authors' Addresses

   Miguel A. Garcia-Martin (Editor)
   Nokia
   P.O. Box 407
   NOKIA GROUP, FIN  00045
   Finland

   Phone: +358 50 480 4586
   EMail: miguel.an.garcia@nokia.com


   Maria-Carmen Belinchon
   Ericsson
   Via de los Poblados 13
   Madrid  28033
   Spain

   Phone: +34 91 339 3535
   EMail: maria.carmen.belinchon@ericsson.com


   Miguel A. Pallares-Lopez
   Ericsson
   Via de los Poblados 13
   Madrid  28033
   Spain

   Phone: +34 91 339 4222
   EMail: miguel-angel.pallares@ericsson.com


   Carolina Canales-Valenzuela
   Ericsson
   Via de los Poblados 13
   Madrid  28033
   Spain

   Phone: +34 91 339 2680
   EMail: carolina.canales@ericsson.com

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   Kalle Tammi
   Nokia
   P.O.Box 785
   Tampere  33101
   Finland

   Phone: +358 40 505 8670
   EMail: kalle.tammi@nokia.com

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Full Copyright Statement

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