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diff --git a/lib/diameter/doc/standard/rfc7075.txt b/lib/diameter/doc/standard/rfc7075.txt new file mode 100644 index 0000000000..f5fd905e72 --- /dev/null +++ b/lib/diameter/doc/standard/rfc7075.txt @@ -0,0 +1,563 @@ + + + + + + +Internet Engineering Task Force (IETF) T. Tsou +Request for Comments: 7075 Huawei Technologies (USA) +Updates: 6733 R. Hao +Category: Standards Track Comcast Cable +ISSN: 2070-1721 T. Taylor, Ed. + Huawei Technologies + November 2013 + + + Realm-Based Redirection In Diameter + +Abstract + + The Diameter protocol includes a capability for message redirection, + controlled by an application-independent "redirect agent". In some + circumstances, an operator may wish to redirect messages to an + alternate domain without specifying individual hosts. This document + specifies an application-specific mechanism by which a Diameter + server or proxy (node) can perform such a redirection when the + Straightforward-Naming Authority Pointer (S-NAPTR) is not used for + dynamic peer discovery. A node performing this new function is + referred to as a "Realm-based Redirect Server". + + This memo updates Sections 6.13 and 6.14 of RFC 6733 with respect to + the usage of the Redirect-Host-Usage and Redirect-Max-Cache-Time + Attribute-Value Pairs (AVPs). + +Status of This Memo + + This is an Internet Standards Track document. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Further information on + Internet Standards is available in Section 2 of RFC 5741. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + http://www.rfc-editor.org/info/rfc7075. + + + + + + + + + + + +Tsou, et al. Standards Track [Page 1] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +Copyright Notice + + Copyright (c) 2013 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 + 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 + 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 + 2. Support of Realm-Based Redirection Within Applications . . . 4 + 3. Realm-Based Redirection . . . . . . . . . . . . . . . . . . . 5 + 3.1. Configuration of the Realm-Based Redirect Server . . . . 5 + 3.2. Behavior of Diameter Nodes . . . . . . . . . . . . . . . 6 + 3.2.1. Behavior at the Realm-Based Redirect Server . . . . . 6 + 3.2.2. Proxy Behavior . . . . . . . . . . . . . . . . . . . 6 + 3.2.3. Client Behavior . . . . . . . . . . . . . . . . . . . 7 + 3.3. The Redirect-Realm AVP . . . . . . . . . . . . . . . . . 7 + 3.4. DIAMETER_REALM_REDIRECT_INDICATION Protocol Error Code . 7 + 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 + 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 + 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 + 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 + 7.2. Informative References . . . . . . . . . . . . . . . . . 9 + + + + + + + + + + + + + + + + + +Tsou, et al. Standards Track [Page 2] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +1. Introduction + + The Diameter base protocol [RFC6733] specifies a basic redirection + service provided by a redirect agent. The redirect indication + returned by the redirect agent is described in Section 6.1.8 and + Sections 6.12 through 6.14 of [RFC6733]. It provides one or more + individual hosts to the message sender as the destination of the + redirected message. + + However, consider the case where an operator has offered a specific + service but no longer wishes to do so. The operator has arranged for + an alternative domain to provide the service. To aid in the + transition to the new arrangement, the original operator maintains a + redirect server to indicate to the message sender the alternative + domain to which the redirect the request should be sent. However, + the original operator should not have to configure the redirect + server with a list of hosts to contact in the alternative operator's + domain; the original operator should simply be able to provide + redirect indications to the domain as a whole. + +1.1. Terminology + + 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]. + + Within this specification, the term "realm-based redirection" is used + to refer to a mode of operation where a realm, rather than an + individual host, is returned as the redirect indication. + + The term "Realm-based Redirect Server" denotes the Diameter node + (Diameter server or proxy) that returns the realm-based redirection. + The behavior of the Realm-based Redirect Server itself is a slight + modification to the behavior of a basic redirect agent as described + in Section 6.1.8 of [RFC6733]. + + The use of a number of terms in this document is consistent with the + usage in [RFC6733]: "Diameter client", "Diameter node", "Diameter + peer", "Diameter server", "proxy", "realm" or "domain", "redirect + agent", and "session" as defined in Section 1.2, and "application" as + defined implicitly by Sections 1.3.4, 2.3, and 2.4. + + + + + + + + + + +Tsou, et al. Standards Track [Page 3] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +2. Support of Realm-Based Redirection Within Applications + + The DNS-based dynamic peer discovery mechanism defined in the + Diameter base protocol [RFC6733] provides a simple mechanism for + realm-based redirection using the S-NAPTR DDDS application [RFC3958]. + When S-NAPTR is used for peer discovery, redirection of Diameter + requests from the original realm to a new realm may be performed by + updating the existing NAPTR resource records (RRs) for the original + realm as follows: the NAPTR RR for the desired application(s) and + supported application protocol(s) provided by the new realm will have + an empty FLAG field and the REPLACEMENT field will contain the new + realm to use for the next DNS lookup. The new realm can be + arbitrary; the restriction in [RFC6733] that the NAPTR replacement + field match the domain of the original query does not apply for + realm-based redirect purposes. + + However, the use of DNS-based dynamic peer discovery is optional for + Diameter implementations. For deployments that do not make use of + S-NAPTR peer discovery, support of realm-based redirection needs to + be specified as part of the functionality supported by a Diameter + application. In this way, support of the considered Diameter + application (discovered during capabilities exchange phase as defined + in Diameter base protocol [RFC6733]) indicates implicit support of + the realm-based redirection mechanism. A new application + specification can incorporate the mechanism specified here by making + it mandatory to implement for the application and referencing this + specification normatively. + + The result of making realm-based redirection an application-specific + behavior is that it cannot be performed by a redirect agent as + defined in [RFC6733], but MUST be performed instead by an + application-aware Diameter node (Diameter server or proxy) (hereafter + called a "Realm-based Redirect Server"). + + An application can specify that realm-based redirection operates only + on complete sessions beginning with the initial message or on every + message within the application, even if earlier messages of the same + session were not redirected. This distinction matters only when + realm-based redirection is first initiated. In the former case, + existing sessions will not be disrupted by the deployment of realm- + based redirection. In the latter case, existing sessions will be + disrupted if they are stateful. + + + + + + + + + +Tsou, et al. Standards Track [Page 4] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +3. Realm-Based Redirection + + This section specifies an extension of the Diameter base protocol + [RFC6733] to achieve realm-based redirection. The elements of this + solution are: + + o a new result code, DIAMETER_REALM_REDIRECT_INDICATION (3011); + + o a new attribute-value pair (AVP), Redirect-Realm (620); and + + o associated behavior at Diameter nodes implementing this + specification. + + This behavior includes the optional use of the Redirect-Host-Usage + and Redirect-Max-Cache-Time AVPs. In this document, these AVPs apply + to the peer discovered by a node acting on the redirect server's + response, an extension to their normal usage as described in Sections + 6.13 and 6.14 of [RFC6733]. + + Section 3.2.2 and Section 3.2.3 describe how a proxy or client may + update its routing table for the application and initial realm as a + result of selecting a peer in the new realm after realm-based + redirection. Note that as a result, the proxy or client will + automatically route subsequent requests for that application to the + new realm (with the possible exception of requests within sessions + already established with the initial realm) until the cached routing + entry expires. This should be borne in mind if the rerouting is + intended to be temporary. + +3.1. Configuration of the Realm-Based Redirect Server + + A Diameter node (Diameter server or proxy) acting as a Realm-based + Redirect Server MUST be configured as follows to execute realm-based + redirection: + + o configured with an application that incorporates realm-based + redirection; + + o the Local Action field of the routing table described in + Section 2.7 of [RFC6733] is set to LOCAL; + + o an application-specific field is set to indicate that the required + local action is to perform realm-based redirection; + + o an associated application-specific field is configured with the + identities of one or more realms to which the request should be + redirected. + + + + +Tsou, et al. Standards Track [Page 5] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +3.2. Behavior of Diameter Nodes + +3.2.1. Behavior at the Realm-Based Redirect Server + + As mentioned in Section 2, an application can specify that realm- + based redirection operates only on complete sessions beginning with + the initial message (i.e., to prevent disruption of established + sessions) or on every message within the application, even if earlier + messages of the same session were not redirected. + + If a Realm-based Redirect Server configured as described in + Section 3.1 receives a request to which realm-based redirection + applies, the Realm-based Redirect Server MUST reply with an answer + message with the 'E' bit set, while maintaining the Hop-by-Hop + Identifier in the header. The Realm-based Redirect Server MUST + include the Result-Code AVP set to + DIAMETER_REALM_REDIRECT_INDICATION. The Realm-based Redirect Server + MUST also include the alternate realm identifier(s) with which it has + been configured, each in a separate Redirect-Realm AVP instance. + + The Realm-based Redirect Server MAY include a copy of the Redirect- + Host-Usage AVP, which SHOULD be set to REALM_AND_APPLICATION. If + this AVP is added, the Redirect-Max-Cache-Time AVP MUST also be + included. Note that these AVPs apply to the peer discovered by a + node acting on the Realm-based Redirect Server's response as + described in the next section. This is an extension of their normal + usage as described by Sections 6.13 and 6.14 of [RFC6733]. + + Realm-based redirection MAY be applied even if a Destination-Host + AVP is present in the request, depending on the operator-based + policy. + +3.2.2. Proxy Behavior + + A proxy conforming to this specification that receives an answer + message with the Result-Code AVP set to + DIAMETER_REALM_REDIRECT_INDICATION MUST attempt to reroute the + original request to a server in a realm identified by a Redirect- + Realm AVP instance in the answer message, and if it fails MUST + forward the indication toward the client. To reroute the request, it + MUST take the following actions: + + 1. Select a specific realm from amongst those identified in + instances of the Redirect-Realm AVP in the answer message. + + 2. If successful, locate and establish a route to a peer in the + realm given by the Redirect-Realm AVP, using normal discovery + procedures as described in Section 5.2 of [RFC6733]. + + + +Tsou, et al. Standards Track [Page 6] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + + 3. If again successful: + + A. update its cache of routing entries for the realm and + application to which the original request was directed, + taking into account the Redirect-Host-Usage and Redirect-Max- + Cache-Time AVPs, if present in the answer. + + B. Remove the Destination-Host (if present) and Destination- + Realm AVPs from the original request and add a new + Destination-Realm AVP containing the realm selected in the + initial step. + + C. Forward the modified request. + + 4. If either of the preceding steps 2-3 fail and additional realms + have been identified in the original answer, select another + instance of the Redirect-Realm AVP in that answer and repeat + steps 2-3 for the realm that it identifies. + +3.2.3. Client Behavior + + A client conforming to this specification MUST be prepared to receive + either an answer message containing a Result-Code AVP set to + DIAMETER_REALM_REDIRECT_INDICATION, or, as the result of proxy + action, some other result from a realm differing from the one to + which it sent the original request. In the case where it receives + DIAMETER_REALM_REDIRECT_INDICATION, the client SHOULD follow the same + steps prescribed in the previous section for a proxy, in order to + both update its routing table and obtain service for the original + request. + +3.3. The Redirect-Realm AVP + + The Redirect-Realm AVP (620) is of type DiameterIdentity. It + specifies a realm to which a node receiving a redirect indication + containing the result code value DIAMETER_REALM_REDIRECT_INDICATION + and the Redirect-Realm AVP SHOULD route the original request. + +3.4. DIAMETER_REALM_REDIRECT_INDICATION Protocol Error Code + + The DIAMETER_REALM_REDIRECT_INDICATION (3011) Protocol error code + indicates that a server has determined that the request within an + application supporting realm-based redirection could not be satisfied + locally, and the initiator of the request SHOULD direct the request + directly to a peer within a realm that has been identified in the + response. When set, the Redirect-Realm AVP MUST be present. + + + + + +Tsou, et al. Standards Track [Page 7] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +4. Security Considerations + + The general recommendations given in Section 13 of the Diameter base + protocol [RFC6733] apply. Specific security recommendations related + to the realm-based redirection defined in this document are described + below. + + Realm-based redirection implies a change in the business relationship + between organizations. Before redirecting a request towards a realm + different from the initial realm, the client or proxy MUST ensure + that the authorization checks have been performed at each connection + along the path toward the realm identified in the realm-based + redirect indication. Details on Diameter authorization path set-up + are given in Section 2.9 of [RFC6733]. Section 13 of [RFC6733] + provides recommendations on how to authenticate and secure each peer- + to-peer connection (using TLS, DTLS, or IPsec) along the way, thus + permitting the necessary hop-by-hop authorization checks. + + Although it is assumed that the administrative domains are secure, a + compromised Diameter node acting as a Realm-based Redirect Server + would be able to redirect a large number of Diameter requests towards + a victim domain that would then be flooded with undesired Diameter + requests. Such an attack is nevertheless discouraged by the use of + secure Diameter peer-to-peer connections and authorization checks, + since these would enable a potential victim domain to discover from + where an attack is coming. That in itself, however, does not prevent + such a DoS attack. + + Because realm-based redirection defined in this document implies that + the Destination-Realm AVP in a client-initiated request can be + changed by a Diameter proxy in the path between the client and the + server, any cryptographic algorithm that would use the Destination- + Realm AVP as input to the calculation performed by the client and the + server would be broken by this form of redirection. Application + specifications that would rely on such cryptographic algorithms + SHOULD NOT incorporate this realm-based redirection. + +5. IANA Considerations + + This specification allocates a new AVP code Redirect-Realm (620) in + the "AVP Codes" registry under "Authentication, Authorization, and + Accounting (AAA) Parameters". + + This specification allocates a new Result-Code value + DIAMETER_REALM_REDIRECT_INDICATION (3011) in the "Result-Code AVP + Values (code 268) - Protocol Errors" registry under "Authentication, + Authorization, and Accounting (AAA) Parameters". + + + + +Tsou, et al. Standards Track [Page 8] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +6. Acknowledgements + + Glen Zorn, Sebastien Decugis, Wolfgang Steigerwald, Mark Jones, + Victor Fajardo, Jouni Korhonen, Avi Lior, and Lionel Morand + contributed comments that helped to shape this document. As + shepherd, Lionel contributed a second set of comments that added + polish to the document before it was submitted to the IESG. Benoit + Claise picked up additional points that were quickly resolved with + Lionel's help. During IETF Last Call Review, Enrico Marocco picked + up some important editorial corrections. Stefan Winter contributed + text on the use of S-NAPTR as an alternative method of realm-based + redirection already specified in [RFC6733]. Derek Atkins performed a + review on behalf of the Security Directorate. Lionel noted one more + correction. + + Finally, this document benefited from comments and discussion raised + by IESG members Stewart Bryant, Stephen Farrell, Barry Leiba, Pete + Resnick, Jari Arkko, and Sean Turner during IESG review. + + The authors are very grateful to Lionel Morand for his active role as + document shepherd. At each stage, he worked to summarize and resolve + comments, making the editor's role easy. Thank you. + +7. References + +7.1. Normative References + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + + [RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn, + "Diameter Base Protocol", RFC 6733, October 2012. + +7.2. Informative References + + [RFC3958] Daigle, L. and A. Newton, "Domain-Based Application + Service Location Using SRV RRs and the Dynamic Delegation + Discovery Service (DDDS)", RFC 3958, January 2005. + + + + + + + + + + + + + +Tsou, et al. Standards Track [Page 9] + +RFC 7075 Realm-Based Redirection In Diameter November 2013 + + +Authors' Addresses + + Tina Tsou + Huawei Technologies (USA) + 2330 Central Expressway + Santa Clara, CA 95050 + USA + + Phone: +1 408 330 4424 + EMail: [email protected] + URI: http://tinatsou.weebly.com/contact.html + + + Ruibing Hao + Comcast Cable + One Comcast Center + Philadelphia, PA 19103 + USA + + Phone: +1 215 286 3991(O) + EMail: [email protected] + + + Tom Taylor (editor) + Huawei Technologies + Ottawa + Canada + + EMail: [email protected] + + + + + + + + + + + + + + + + + + + + + + +Tsou, et al. Standards Track [Page 10] + |