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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SIPPING D. Petrie 3 Internet-Draft SIPez LLC. 4 Intended status: Standards Track S. Channabasappa, Ed. 5 Expires: April 27, 2008 CableLabs 6 October 25, 2007 8 A Framework for Session Initiation Protocol User Agent Profile Delivery 9 draft-ietf-sipping-config-framework-13 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on April 27, 2008. 36 Copyright Notice 38 Copyright (C) The IETF Trust (2007). 40 Abstract 42 This document specifies a framework to enable configuration of 43 Session Initiation Protocol (SIP) User Agents in SIP deployments. 44 The framework provides a means to deliver profile data that User 45 Agents need to be functional, automatically and with minimal or no 46 User and Administrative intervention. The framework describes how 47 SIP User Agents can discover sources, request profiles and receive 48 notifications related to profile modifications. As part of this 49 framework, a new SIP event package is defined for notification of 50 profile changes. The framework provides minimal data retrieval 51 options to ensure interoperability. The framework does not include 52 specification of the profile data within its scope. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 58 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 3.1. Reference Model . . . . . . . . . . . . . . . . . . . . . 6 60 3.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 7 61 3.3. Profile Types . . . . . . . . . . . . . . . . . . . . . . 9 62 3.4. Profile delivery stages . . . . . . . . . . . . . . . . . 10 63 4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 10 64 4.1. Simple Deployment Scenario . . . . . . . . . . . . . . . . 11 65 4.2. Devices supporting multiple users from different 66 Service Providers . . . . . . . . . . . . . . . . . . . . 12 67 5. Profile Delivery Framework . . . . . . . . . . . . . . . . . . 14 68 5.1. Profile delivery stages . . . . . . . . . . . . . . . . . 14 69 5.1.1. Profile Enrollment . . . . . . . . . . . . . . . . . . 14 70 5.1.2. Content Retrieval . . . . . . . . . . . . . . . . . . 17 71 5.1.3. Change Notification . . . . . . . . . . . . . . . . . 17 72 5.1.4. Enrollment Data and Caching . . . . . . . . . . . . . 18 73 5.2. Securing Profile Delivery . . . . . . . . . . . . . . . . 21 74 5.2.1. Securing Profile Enrollment . . . . . . . . . . . . . 21 75 5.2.2. Securing Content Retrieval . . . . . . . . . . . . . . 23 76 5.2.3. Securing Change Notification . . . . . . . . . . . . . 24 77 5.3. Additional Considerations . . . . . . . . . . . . . . . . 24 78 5.3.1. Identities and Credentials . . . . . . . . . . . . . . 24 79 5.3.2. Profile Enrollment Request Attempt . . . . . . . . . . 26 80 5.3.3. Device Types . . . . . . . . . . . . . . . . . . . . . 30 81 5.3.4. Profile Data . . . . . . . . . . . . . . . . . . . . . 30 82 5.3.5. Profile Data Frameworks . . . . . . . . . . . . . . . 31 83 5.3.6. Additional Profile Types . . . . . . . . . . . . . . . 31 84 5.3.7. Deployment considerations . . . . . . . . . . . . . . 32 85 5.4. Usage of Outbound . . . . . . . . . . . . . . . . . . . . 32 86 6. Event Package Definition . . . . . . . . . . . . . . . . . . . 33 87 6.1. Event Package Name . . . . . . . . . . . . . . . . . . . . 33 88 6.2. Event Package Parameters . . . . . . . . . . . . . . . . . 33 89 6.3. SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 36 90 6.4. Subscription Duration . . . . . . . . . . . . . . . . . . 36 91 6.5. NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . 37 92 6.6. Notifier Processing of SUBSCRIBE Requests . . . . . . . . 37 93 6.7. Notifier Generation of NOTIFY Requests . . . . . . . . . . 37 94 6.8. Subscriber Processing of NOTIFY Requests . . . . . . . . . 38 95 6.9. Handling of Forked Requests . . . . . . . . . . . . . . . 38 96 6.10. Rate of Notifications . . . . . . . . . . . . . . . . . . 39 97 6.11. State Agents . . . . . . . . . . . . . . . . . . . . . . . 39 98 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 99 7.1. Example 1: Device requesting profile . . . . . . . . . . . 39 100 7.2. Example 2: Device obtaining change notification . . . . . 42 101 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46 102 8.1. SIP Event Package . . . . . . . . . . . . . . . . . . . . 46 103 8.2. Registry of SIP configuration profile types . . . . . . . 46 104 9. Security Considerations . . . . . . . . . . . . . . . . . . . 47 105 9.1. Local-network profile . . . . . . . . . . . . . . . . . . 49 106 9.2. Device profile . . . . . . . . . . . . . . . . . . . . . . 50 107 9.3. User profile . . . . . . . . . . . . . . . . . . . . . . . 51 108 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 52 109 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 53 110 11.1. Normative References . . . . . . . . . . . . . . . . . . . 53 111 11.2. Informative References . . . . . . . . . . . . . . . . . . 54 112 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 54 113 Intellectual Property and Copyright Statements . . . . . . . . . . 56 115 1. Introduction 117 SIP User Agents require configuration data to function properly. 118 Examples include local network, device and user specific information. 119 A configuration data set specific to an entity is termed a profile. 120 For example, device profile contains the configuration data related 121 to a device. The process of providing devices with one or more 122 profiles is termed profile delivery. Ideally, this profile delivery 123 process should be automatic and require minimal or no user 124 intervention. 126 Many deployments of SIP User Agents require dynamic configuration and 127 cannot rely on pre-configuration. This framework provides a standard 128 means of providing dynamic configuration which simplifies deployments 129 containing SIP User Agents from multiple vendors. This framework 130 also addresses change notifications when profiles change. However, 131 the framework does not define the content or format of the profile, 132 leaving that to future standardization activities. 134 This document is organized as follows. Section 3 provides a high- 135 level overview of the abstract components, profiles, and the profile 136 delivery stages. Section 4 provides some motivating use cases. 137 Section 5 provides details of the framework operation and 138 requirements. Section 6 provides a concise event package definition. 139 Section 7 follows with illustrative examples of the framework in use. 141 2. Terminology 143 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 144 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 145 document are to be interpreted as described in RFC 2119 [RFC2119]. 147 This document also reuses the SIP terminology defined in [RFC3261] 148 and [RFC3265], and specifies the usage of the following terms. 150 Device: software or hardware entity containing one or more SIP user 151 agents. It may also contain entities such as a DHCP client. 153 Device Provider: the entity responsible for managing a given device. 155 Local Network Provider: the entity that controls the local network 156 to which a given device is connected. 158 SIP Service Provider: the entity providing SIP services to users. 159 This can refer to private enterprises or public entities. 161 Profile: configuration data set specific to an entity (e.g., user, 162 device, local network or other). 164 Profile Type: a particular category of Profile data (e.g., User, 165 Device, Local Network or other). 167 Profile Delivery Server (PDS): the source of a Profile, it is the 168 logical collection of the Profile Notification Component (PNC) and 169 the Profile Content Component(PCC). 171 Profile Notification Component (PNC): the logical component of a 172 Profile Delivery Server that is responsible for enrolling devices 173 and providing profile notifications. 175 Profile Content Component (PCC): the logical component of a Profile 176 Delivery Server that is responsible for storing, providing access 177 to, and accepting profile content. 179 Profile Delivery Stages: the processes that lead a device to obtain 180 profile data, and any subsequent changes, are collectively called 181 profile delivery stages. 183 3. Overview 185 This section provides an overview of the configuration framework. It 186 presents the reference model, the motivation, the profile delivery 187 stages and a mapping of the concepts to specific use cases. It is 188 meant to serve as a reference section for the document, rather than 189 providing a specific logical flow of material, and it may be 190 necessary to revisit these sections for a complete appreciation of 191 the framework. 193 The SIP UA Profile Delivery Framework uses a combination of SIP event 194 messages (SUBSCRIBE and NOTIFY; [RFC3265]) and traditional file 195 retrieval protocols, such as HTTP [RFC2616], to discover, monitor, 196 and retrieve configuration profiles. The framework defines three 197 types of profiles (local-network, device, and user) in order to 198 separate aspects of the configuration which may be independently 199 managed by different administrative domains. The initial SUBSCRIBE 200 message for each profile allows the UA to describe itself (both its 201 implementation and the identity requesting the profile), while 202 requesting access to a profile by type, without prior knowledge of 203 the profile name or location. Discovery mechanisms are specified to 204 help the UA form the subscription URI (the Request URI for the SIP 205 SUBSCRIBE). The SIP UAS handling these subscriptions is the Profile 206 Delivery Server (PDS). When the PDS accepts a subscription, it sends 207 a NOTIFY to the device. The initial NOTIFY from the PDS for each 208 profile may contain profile data or a reference to the location of 209 the profile, to be retrieved using HTTP or similar file retrieval 210 protocols. By maintaining a subscription to each profile, the UA 211 will receive additional NOTIFY messages if the profile is later 212 changed. These may contain a new profile, a reference to a new 213 profile, or a description of profile changes, depending on the 214 Content-Type [RFC3261] in use by the subscription. The framework 215 describes the mechanisms for obtaining three different profile types, 216 but does not describe the data model they utilize (the data model is 217 out of scope for this specification). 219 3.1. Reference Model 221 The design of the framework was the result of a careful analysis to 222 identify the configuration needs of a wide range of SIP deployments. 223 As such, the reference model provides for a great deal of 224 flexibility, while breaking down the interactions to their basic 225 forms, which can be reused in many different scenarios. 227 The reference model for the framework defines the interactions 228 between the Profile Delivery Server(PDS) and the device. The device 229 needs the profile data to function effectively in the network. The 230 PDS is responsible for responding to device requests and providing 231 the profile data. The reference model is illustrated in Figure 1. 233 +-------------------------+ 234 +--------+ | Profile Delivery Server | 235 | Device |<==========================>| +---+ +---+ | 236 +--------+ | |PNC| |PCC| | 237 | +---+ +---+ | 238 +-------------------------+ 240 PNC = Profile Notification Component 241 PCC = Profile Content Component 243 Figure 1: Framework Reference Model 245 The PDS is subdivided into two logical components: 246 o Profile Notification Component (PNC), responsible for enrolling 247 devices for profiles and providing profile change notifications; 248 o Profile Content Component (PCC), responsible for storing, 249 providing access to, and accepting modifications related to 250 profile content. 252 3.2. Motivation 254 The motivation for the framework can be demonstrated by applying the 255 reference model presented in Section 3.1 to two scenarios that are 256 representative of the two ends of a spectrum of potential SIP 257 deployments. 259 In the simplest deployment scenario, a device connects through a 260 network that is controlled by a single provider who provides the 261 local-network, manages the devices, and offers services to the users. 262 The provider propagates profile data to the device that contains all 263 the necessary information to obtain services in the network 264 (including information related to the local-network and the users). 265 This is illustrated in Figure 2. An example is a simple enterprise 266 network that supports SIP-based devices. 268 -------------- 269 / Local-network, \ 270 | Device & Service | 271 \ Provider / 272 ---------------- 273 | 274 | 275 -------- 276 | Device | 277 -------- 278 | 279 | 280 ---- 281 |User| 282 ---- 284 Figure 2: Simple Deployment Model 286 In more complex deployments, devices connect via a local network that 287 is not controlled by the SIP Service Provider, such as devices that 288 connect via available public WiFi hotspots. In such cases, local 289 network providers may wish to provide local network information such 290 as bandwidth constraints to the devices. 292 Devices may also be controlled by device providers that are 293 independent of the SIP service provider who provides user services, 294 such as kiosks that allow users to access services from remote 295 locations. In such cases the profile data may have to be obtained 296 from different profile sources: local network provider, device 297 provider and SIP service provider. This is indicated in Figure 3 . 299 -------- 300 / SIP \ 301 | Service | -> Provides 'user' profile 302 | Provider | data (e.g., services 303 \ / configuration) 304 -------- -------- 305 | / \ 306 | | Device | -> Provides 'device' profile 307 | | Provider | data (e.g., device specifics) 308 | \ / 309 | --------- 310 | / 311 | / ------- 312 | / / Local \ 313 | / | Network | 314 | | | Provider | -> Provides 'local-network' profile 315 | | \ / data (e.g., bandwidth) 316 | | ------- 317 | | / 318 | | / 319 | | | 320 =================== 321 ( Local Network ) 322 =================== 323 | 324 | 325 -------- 326 | Device | -> Needs the 'local-network' 327 -------- and 'device' profile 328 / \ 329 / \ 330 ------ ------ 331 |User A| |User B| -> Users need 'user' profiles 332 ------ ------ 333 Figure 3: Complex Deployment Model 335 In either case, Providers need to deliver to the device, profile data 336 that is required to participate in their network. Examples of 337 profile data include the list of codecs that can be used and the SIP 338 proxies to connect to for services. Pre-configuration of such 339 information is one option if the device is always served by the same 340 set of Providers. In all other cases, the profile delivery needs to 341 be automated and consistent across Providers. Given the presence of 342 a number of large deployments where pre-configuration is neither 343 desired nor optimal, there is a need for a common configuration 344 framework such as the one described in this document. 346 Further, the former deployment model can be accomplished by the 347 device obtaining profile data from a single provider. However, the 348 latter deployment model requires the device to obtain profile data 349 from different providers. To address either deployment, or any 350 variation in between, one needs to allow for profile delivery via 351 one, or more, Providers. The framework accomplishes this by 352 specifying multiple profile types and a set of profile delivery 353 stages to obtain them. These are introduced in the sub-sections to 354 follow. 356 3.3. Profile Types 358 The framework handles the presence of potentially different Providers 359 by allowing for multiple profile types. Clients request each profile 360 and obtain them from the same, or different, Providers. Additional 361 profile types may also be specified. A deployment can also choose to 362 pre-configure the device to request only a subset of the specified 363 profile types. The framework specifies three basic profile types, as 364 follows: 366 Local Network Profile: contains configuration data related to the 367 local network to which a device is directly connected, provided by 368 the Local Network Provider. 370 Device Profile: contains configuration data related to a specific 371 device, provided by the Device Provider. 373 User Profile: contains configuration data related to a specific 374 User, as required to reflect that user's preferences and the 375 particular services subscribed to. It is provided by the SIP 376 Service Provider. 378 PDSs and devices will implement all the three profile types. Unless 379 configured otherwise, a device will try to obtain all the three 380 profile types. A retrieval order is specified by the framework. The 381 data models associated with each profile type is out of scope for 382 this document. Follow-on standardization activities are expected to 383 specify such data models. 385 3.4. Profile delivery stages 387 The framework specified in this document requires a device to 388 explicitly request profiles. It also requires one or more PDSs which 389 provide the profile data. The processes that lead a device to obtain 390 profile data, and any subsequent changes, can be explained in three 391 stages, termed the profile delivery stages. 393 Profile Enrollment: the process by which a device requests, and if 394 successful, enrolls with a PDS capable of providing a profile. A 395 successful enrollment is indicated by a notification containing 396 the profile information (contents or content indirection 397 information). Depending on the request, this could also result in 398 a subscription to notification of profile changes. 400 Profile Content Retrieval: the process by which a device retrieves 401 profile contents, if the profile enrollment resulted in content 402 indirection information. 404 Profile Change Notification: the process by which a device is 405 notified of any changes to an enrolled profile. This may provide 406 the device with modified profile data or content indirection 407 information. 409 4. Use Cases 411 This section provides a small, non-comprehensive set of 412 representative use cases to further illustrate how this Framework can 413 be utilized in SIP deployments. The first use case is simplistic in 414 nature, whereas the second is relatively complex. The use cases 415 illustrate the effectiveness of the framework in either scenario. 417 For Security Considerations please refer to Section 5 and Section 9. 419 4.1. Simple Deployment Scenario 421 Description: Consider a deployment scenario (e.g., a small private 422 enterprise) where a single entity enables the local network, manages 423 deployed devices and provides SIP services. The devices only attach 424 to the local network, and are pre-configured with a single user. 426 The following assumptions apply: 427 o The device profile data contains all the information necessary 428 for the device to participate in the local network and obtain 429 services. 430 o The device is pre-configured to only request the device profile. 431 o The enrollment notification contains the profile data (profile 432 content retrieval is not required). 433 o There are no proxies in the network. 435 Figure 4 illustrates this use case and highlights the communications 436 relevant to the framework specified in this document. 438 +----------------------+ 439 +--------+ | Local Network, Device| 440 | Device | |& SIP Service Provider| 441 | | | | 442 +--------+ | DHCP PDS | 443 +----------------------+ 444 | | | 445 (A) |<============== DHCP =============>| | 446 | | 447 | | 448 | | 449 (B) |<=========== Profile Enrollment ============>| 450 | | Profile data 451 | | is modified 452 | | 453 (C) |<============ Profile Change ================| 454 | Notification | 455 | | 456 | | 457 Figure 4: Use Case 1 459 The following is an explanation of the interactions in Figure 4. 460 (A) Upon initialization, the device obtains IP configuration 461 parameters using DHCP. 462 (B) The device performs Profile Enrollment for the device profile; 463 the device profile data is contained in the enrollment 464 notification. 465 (C) Due to a modification of the device profile, a Profile Change 466 Notification is sent across to the device, along with the 467 modified profile. 469 4.2. Devices supporting multiple users from different Service Providers 471 Description: Consider a single device (e.g., Kiosk at an airport) 472 that allows multiple users to obtain services from a list of pre- 473 configured SIP Service Providers. 475 The following assumptions apply: 476 o Provider A is the Device and Local Network Provider for the 477 device, and the SIP Service Provider for user A; Provider B is 478 the SIP Service Provider for user B. 479 o Profile enrollment always results in content indirection 480 information requiring profile content retrieval. 481 o Communication between the device and the PDSs is facilitated by 482 SIP proxies. 484 Figure 4 illustrates the use case and highlights the communications 485 relevant to the framework specified in this document. 487 User User 488 A B +----------------------+ +----------------------+ 489 +--------+ | Provider | | Provider | 490 | Device | | A | | B | 491 | | | | | | 492 +--------+ | DHCP PROXY PDS | | PROXY PDS | 493 +----------------------+ +----------------------+ 494 | | | | | | 495 (A) |<====DHCP====>| | | | | 496 | | | | | 497 | | | | | 498 | Profile Enrollment | | | | 499 (B) ||<====>| | | 500 | 501 | <> 502 | 503 | 504 | Profile Enrollment | | | | 505 (C) |<== device profile ==> |<====>| | | 506 | 507 | <> 508 | 509 . 510 . 511 . 512 [[User A obtains services]] 514 | Profile Enrollment | | | | 515 (D) |<= user profile (A) => |<====>| | | 516 | | | | | 517 | 518 | <> 519 . 520 . 521 . 522 . 523 [[User B obtains services]] 525 | 526 | Profile Enrollment | | 527 (E) |<=========== user profile (B) ==========>|<=========>| 528 | | | 529 | <> 530 | 531 Figure 5: Use Case 2 533 The following is an explanation of the interactions in Figure 5. 534 (A) Upon initialization, the device obtains IP configuration 535 parameters using DHCP. This also provides the local domain 536 information to help with local-network profile enrollment. 537 (B) The device requests profile enrollment for the local network 538 profile. It receives an enrollment notification containing 539 content indirection information from Provider A's PDS. The 540 device retrieves the profile (this contains useful information 541 such as firewall port restrictions and available bandwidth). 542 (C) The device then requests profile enrollment for the device 543 profile. It receives an enrollment notification resulting in 544 device profile content retrieval. The device initializes the 545 User interface for services. 546 (D) User A with a pre-existing service relationship with Provider A 547 attempts communication via the user Interface. The device uses 548 the user supplied information (including any credential 549 information) and requests profile enrollment for user A's 550 profile. Successful enrollment and profile content retrieval 551 results in services for user A. 552 (E) At a different point in time, user B with a service relationship 553 with Provider B attempts communication via the user Interface. 554 It enrolls and retrieves user B's profile and this results in 555 services for user B. 557 5. Profile Delivery Framework 559 This section specifies the profile delivery framework. It provides 560 the requirements for the three profile delivery stages introduced in 561 Section 3.4 and presents the associated security requirements. It 562 also presents considerations such as back-off and retry mechanisms. 564 5.1. Profile delivery stages 566 The three profile delivery stages - enrollment, content retrieval and 567 change notification - apply to any profile type specified for use 568 with this framework. The following sub-sections provide the 569 requirements associated with each stage. 571 5.1.1. Profile Enrollment 573 Profile enrollment is the process by means of which a device 574 requests, and receives, profile data. Each profile type specified in 575 this document requires an independent enrollment request. However, a 576 particular PDS can support enrollment for one or more profile types. 578 Profile enrollment consists of the following operations, in the 579 specified order. 581 Enrollment request transmission 583 Profile enrollment is initiated when the device transmits a SIP 584 SUBSCRIBE request [RFC3265] for the 'ua-profile' event package, 585 specified in Section 6. The profile being requested is indicated 586 using the 'profile-type' parameter. The device MUST transmit the 587 SIP SUBSCRIBE message via configured outbound proxies for the 588 destination domain, or in accordance with RFC 3263 [RFC3263]. 590 The device needs certain data to create an enrollment request, 591 form a Request URI, and authenticate to the network. This 592 includes the profile provider's domain name, identities and 593 credentials. Such data can be "configured" during device 594 manufacturing, by the user, or via profile data retrieval (see 595 Section 5.3.1). The data can also be "discovered" using the 596 procedures specified by this framework. The "discovered" data can 597 be retained across device resets (but not across factory resets) 598 and such data is referred to as "cached". Thus, data can be 599 configured, discovered or cached. The following requirements 600 apply. 602 * If the device is configured with a specific domain name (for 603 the local network provider or device provider), it MUST NOT 604 attempt "discovery" of the domain name. This is the case when 605 the device is pre-configured (e.g., via a UI) to be managed by 606 specific entities. 607 * The device MUST only use data associated with the provider's 608 domain in an enrollment request. As an example, when the 609 device is requesting a local-network profile in the domain 610 'example.net', it cannot present a user AoR associated with the 611 local domain 'example.com'. 612 * The device SHOULD adhere to the following order of data usage: 613 configured, cached and discovered. An exception is when the 614 device is explicitly configured to use a different order. 616 Upon failure to obtain the profile using any methods specified in 617 this framework, the device MAY provide a user interface to allow 618 for user intervention. This can result in temporary, one-time 619 data to bootstrap the device. Such temporary data is not 620 considered to be "configured" and is not expected to be cached 621 across resets. The configuration obtained using such data MAY 622 provide the configuration data required for the device to continue 623 functioning normally. 625 Devices attempting enrollment MUST comply with the SIP-specific 626 event notification specified in [RFC3265], the event package 627 requirements specified in Section 6.2, and the security 628 requirements specified in Section 5.2. 630 Enrollment request admittance 632 A PDS or a SIP proxy will receive a transmitted enrollment 633 request. If a SIP infrastructure element receives the request, it 634 will relay it to the authoritative proxy for the domain indicated 635 in the Request-URI (the same way it would handle any other 636 SUBSCRIBE message). The authoritative proxy is required to 637 examine the request (e.g., event package) and transmit it to a PDS 638 capable of addressing the profile enrollment request. 640 A PDS receiving the enrollment request SHOULD respond to the 641 request, or proxy it to a PDS that can respond. An exception is 642 when a policy prevents a response (e.g., recognition of a DoS 643 attack, an invalid device, etc.). The PDS then verifies the 644 identity presented in the request and performs any necessary 645 authentication. Once authentication is successful, the PDS MAY 646 admit or reject the enrollment request, based on applicable 647 authorization policies. A PDS admitting the enrollment request 648 indicates it via a 2xx-class response, as specified in [RFC3265]. 650 Refer to Section 6.6 and Section 5.2 for more information on 651 subscription request handling and security requirements, 652 respectively. 654 Enrollment request acceptance 656 A PDS that admits the enrollment request verifies applicable 657 policies, identifies the requested profile data and prepares a SIP 658 NOTIFY message to the device. Such a notification can either 659 contain the profile data or contain content indirection 660 information that results in the device performing profile content 661 retrieval. The PDS then transmits the prepared SIP notification. 662 When the device successfully receives and accepts the SIP 663 notification, profile enrollment is complete. 665 When it receives the SIP NOTIFY message, indicating successful 666 profile enrollment, the device MUST make the new profile effective 667 within the specified timeframe, as described in Section 6.2. 669 Once profile enrollment is successful, the PDS MUST consider the 670 device enrolled for the specific profile, for the duration of the 671 subscription. 673 5.1.2. Content Retrieval 675 A successful profile enrollment leads to an initial SIP notification, 676 and may result in subsequent change notifications. Each of these 677 notifications can either contain profile data, or content indirection 678 information. If it contains content indirection information, the 679 device is required to retrieve the profile data using the specified 680 content retrieval protocols. This process is termed profile content 681 retrieval. For information regarding the use of the SIP NOTIFY 682 message body please refer to Section 6.5. 684 Devices and PDSs implementing this framework MUST implement two 685 content retrieval protocols: HTTP and HTTPS as specified in [RFC2616] 686 and [RFC2818], respectively. Future enhancements or usage of this 687 framework may specify additional or alternative content retrieval 688 protocols. For security requirements and considerations please refer 689 to Section 5.2. 691 5.1.3. Change Notification 693 Profile data can change over time. Changes can be initiated by 694 various entities (e.g., via the device, back-office components and 695 end-user web interfaces) and for various reasons (e.g., change in 696 user preferences and modifications to services). Profiles may also 697 be shared by multiple devices simultaneously. When a profile is 698 changed the PDS MUST inform all the devices currently enrolled for 699 the specific profile. This process of informing a device of any 700 changes to the profile that it is currently enrolled for is termed 701 change notification. 703 The PDS provides change notification using a SIP notification (SIP 704 NOTIFY message as specified in [RFC3265]). The SIP notification may 705 provide the changes, a revised profile or content indirection which 706 contains a pointer to the revised data. When a device successfully 707 receives a profile change notification for an enrolled profile, it 708 MUST act upon the changes prior to the expiration of the 709 'effective-by' parameter. 711 For NOTIFY content please refer to Section 6.5. 713 5.1.4. Enrollment Data and Caching 715 The requirements for the contents of the SIP SUBSCRIBE used to 716 request profile enrollment are described in this section. The data 717 required can be configured, cached or discovered - depending on the 718 profile type. If the data is not configured, the device MUST use 719 relevant cached data or proceed with data discovery. This section 720 describes the requirements for creating a SIP SUBSCRIBE for 721 enrollment, the caching requirements and how data can be discovered. 723 5.1.4.1. Local-Network Profile 725 To create a Subscription URI to request the local-network profile a 726 device needs the local network domain name, the device identifier and 727 optionally a user AoR with associated credentials (if one is 728 configured). Since the device can be potentially initialized in a 729 different local-network each time, it SHOULD NOT cache the local 730 network domain, the SIP subscription URI or the local-network profile 731 data across resets. An exception to this is when the device can 732 confirm that it is reinitialized in the same network (using means 733 outside the scope of this document). Thus, in most cases, the device 734 needs to discover the local network domain name. The device 735 discovers this by establishing IP connectivity in the local network 736 (such as via DHCP or pre-configured IP information). Once 737 established, the device MUST attempt to use the local network domain 738 obtained via pre-configuration, if available. If it is not pre- 739 configured, it MUST employ dynamic discovery using DHCPv4 ([RFC2132], 740 Domain Name option) or DHCPv6 ([RFC4704]). Once the local network 741 domain is obtained, the device creates the SIP SUBSCRIBE for 742 enrollment as described below. 743 o The device MUST NOT populate the user part of the Request URI. 744 The device MUST set the host portion of the Request URI to the 745 dot-separated concatenation of "_sipuaconfig" and the local 746 network domain (see example below). 747 o If the device has been configured with a user AoR for the local 748 network domain (verified as explained in Section 5.2) it MUST use 749 it to populate the "From" field, unless configured not to (due to 750 privacy concerns, for example). Otherwise, the device MUST set 751 the "From" field to a value of "anonymous@anonymous.invalid". 752 o The device MUST include the +sip.instance parameter within the 753 'Contact' header, as specified in [I-D.ietf-sip-outbound]. The 754 device MUST ensure that the value of this parameter is the same as 755 that included in any subsequent profile enrollment request. 757 For example, if the device requested and received the local domain 758 name via DHCP to be: airport.example.net, then the local-network 759 Profile SUBSCRIBE Request URI would look like: 761 sip:_sipuaconfig.airport.example.net 763 The local-network profile SUBSCRIBE Request URI does not have a user 764 part so that the URI is distinct between the "local" and "device" 765 URIs when the domain is the same for the two. This provides a means 766 of routing to the appropriate PDS in domains where there are distinct 767 servers. 769 The From field is populated with the user AoR, if available. This 770 allows the local network provider to propagate user-specific profile 771 data, if available. The "+sip.instance" parameter within the 772 "Contact" header is set to the device identifier or specifically, the 773 SIP UA instance. Even though every device may get the same (or 774 similar) local-network Profile, the uniqueness of the "+sip.instance" 775 parameter provides an important capability. Having unique instance 776 ID fields allows the management of the local network to track devices 777 present in the network and consequently also manage resources such as 778 bandwidth allocation. 780 5.1.4.2. Device Profile Type 782 Once associated with a device, the device provider is not expected to 783 change frequently. An exception is a user who changes device 784 providers, but retains the device. Thus, the device is allowed to, 785 and SHOULD cache the Subscription URI for the device profile upon 786 successful enrollment. Exceptions include cases where the device 787 identifier has changed (e.g., new network card), device provider 788 information has changed (e.g., user initiated change) or the device 789 cannot obtain its profile using the Subscription URI. Thus, when 790 available, the device MUST use a cached Subscription URI. If no 791 cached URI is available then it needs to create a Subscription URI. 792 To create a Subscription URI, the device needs a device identity and 793 the device provider's domain name. Unless already configured, the 794 device needs to discover the necessary information and form the 795 subscription URI. In such cases, the following requirements apply 796 for creating a Subscription URI for requesting the device profile: 798 o The device MUST use the device identifier and the device 799 provider's domain name to form the Request URI. 800 o The device MUST set the "From" field to a value of anonymous@ 801 . 802 o The device MUST include the +sip.instance parameter within the 803 'Contact' header, as specified in [I-D.ietf-sip-outbound]. The 804 device MUST use the same value as the one presented while 805 requesting the local-network profile. 807 Note that the discovered AoR for the Request URI can be overridden by 808 a special, provisioned, AoR that is unique to the device. In such 809 cases, the provisioned AoR is used to form the Request URI and to 810 populate the From field. 812 If the device is not configured with an AoR, and needs a domain name, 813 it can either use a configured domain name, if available, or discover 814 it. The options to discover are described below. The device MUST 815 use the results of each successful discovery process for one 816 enrollment attempt, in the order specified below. 818 o Option 1: Devices that support DHCP MUST attempt to obtain the 819 hostname of the outbound proxy during the DHCP process, using the 820 DHCP option for SIP servers defined in [RFC3361] or [RFC3319] (for 821 IPv4 and IPv6 respectively). 822 o Option 2: Devices that support DHCP MUST attempt to obtain the 823 local IP network domain during the DHCP process (refer to 824 [RFC2132] and [RFC4704] ). 825 o Option 3: Devices MUST use the local network domain name 826 (configured or discovered to retrieve the local-network profile), 827 prefixing it with the label "_sipuaconfig". 829 If the device needs to create a subscription URI and needs to use its 830 device identifier, it MUST use the UUID-based URN representation as 831 specified in [RFC4122]. The following requirements apply: 832 o When the device has a non-alterable MAC address it SHOULD use 833 version 1 UUID representation with the timestamp and clock 834 sequence bits set to a value of '0'. This will allow for easy 835 recognition, and uniqueness of MAC address based UUIDs. An 836 exception is the case where the device supports independent device 837 configuration for more than one SIP UA. An example would be 838 multiple SIP UAs on the same platform. 839 o If the device cannot use a non-alterable MAC Address, it SHOULD 840 use an alternative non-alterable device identifier. For example, 841 the International Manufacturer's Equipment Identifier (IMEI) for 842 mobile devices. 843 o If the device cannot use a non-alterable MAC Address, it MUST be 844 use the same approach as defining a user agent Instance ID in 845 [I-D.ietf-sip-outbound]. 846 o As a note, when the URN is used as the user part of the Request 847 URI, it MUST be URL escaped 848 The colon (":") is not a legal character in the user part of an 849 addr-spec ([RFC4122]), and must be escaped. 851 For example, the instance ID: 852 urn:uuid:f81d4fae-7ced-11d0-a765-00a0c91e6bf6@example.com 854 would be escaped to look as follows in a URI: 856 sip:urn%3auuid%3af81d4fae-7ced-11d0-a765-00a0c91e6bf6@ 857 example.com 859 The ABNF for the UUID representation is provided in [RFC4122] 861 5.1.4.3. User Profile Type 863 To create a Subscription URI to request the user profile on behalf of 864 a user, the device needs to know the user's AoR. This can be 865 statically or dynamically configured on the device (e.g., user input, 866 or propagated as part of the device profile). Similar to device 867 profiles, the content and propagation of user profiles may differ, 868 based on deployment scenarios (i.e., users belonging to the same 869 domain may - or may not - be provided the same profile). To create a 870 subscription URI, the following rules apply: 871 o The device MUST set the Request URI to the user AoR. 872 o The device MUST populate the "From" field with the user AoR. 874 5.2. Securing Profile Delivery 876 Profile data can contain sensitive information that needs to be 877 secured, such as identities and credentials. Security involves 878 authentication, message integrity and privacy. Authentication is the 879 process by which you verify that an entity is who it claims to be, 880 such as a user AoR presented during profile enrollment. Message 881 integrity provides the assurance that the message contents 882 transmitted between two entities, such as between the PDS and the 883 device, has not been modified during transit. Privacy ensures that 884 the message contents have not been subjected to monitoring by 885 unwanted elements, during transit. At a minimum, authentication and 886 message integrity are required to ensure that the profile contents 887 were received by a valid entity, from a valid source, and without any 888 modifications during transit. For profiles that contain sensitive 889 data, privacy is required to ensure that the data is not snooped by 890 unwanted elements. 892 For an overview of potential security threats, refer to Section 9.The 893 requirements to address the concerns are required for all stages of 894 profile delivery, and are presented in the following subsections. 896 5.2.1. Securing Profile Enrollment 898 During profile enrollment, the device needs to authenticate two 899 entities. The next-hop entity, i.e., a proxy or a PDS, to which the 900 device transmits the profile enrollment request, and the initial 901 notification from the PDS. On the Provider's side, a PDS that 902 recognizes an identity, such as the user AoR, that will result in 903 sensitive (or even non-generic) data included in the initial or 904 change notifications, will need to authenticate the device claiming 905 such identities. 907 Authentication of the next-hop entity by the device is accomplished 908 by using the procedures specified in [RFC2818], Section 3.1, over an 909 establish TLS connection ([RFC4346]). The 'Server Identity' in this 910 case is always the domain of the next-hop SIP entity. A device 911 presenting a SIPS URI as a user AoR MUST establish TLS with the next- 912 hop SIP entity to which it sends the enrollment request. In all 913 other cases, the device SHOULD still attempt establishment of TLS 914 with the next-hop SIP entity. An exception is when it is explicitly 915 configured not to. If it attempts to establish TLS and it fails 916 because the next-hop SIP entity does not support TLS, the device 917 SHOULD attempt other resolved next-hop SIP entities prior to 918 attempting enrollment without TLS. If the device attempts to 919 establish a TLS session and fails to verify the next-hop entity 920 (e.g., the domain name could not be verified) the device MUST NOT 921 continue with the current enrollment request, and must retry with 922 other resolved next-hop SIP entities. If the device is attempting to 923 establish TLS, and exhausts the entire list of next-hop entities, 924 then: 926 o if the device has a user interface, and unless configured not to, 927 the device SHOULD prompt the user if it can continue without TLS; 928 o if the device has no user interface, and unless configured not to, 929 the device MUST retry enrollment without TLS and without 930 presenting any configured user AoR (note: this means that user 931 profiles cannot be retrieved). 933 In the absence of a Server Identity authenticated TLS session with 934 the next-hop SIP entity: 935 o the device MUST NOT respond to any authentication challenges; 936 o the device MUST ignore any notifications containing sensitive 937 profile data. 939 Once enrolled, the device obtains the initial notification. This is 940 authenticated using two methods. If this initial notification was 941 transmitted on the mutually authenticated TLS session established for 942 enrollment requests, then it is considered authenticated. If not, 943 the device MUST verify the presence of a SIP Identity header from the 944 PDS and validate that it belongs to the Provider's domain. If the 945 SIP Identity header is absent or the device cannot validate it, the 946 device MUST reject any sensitive profile data. If the SIP Identity 947 header is present, and the device cannot validate it, then it MUST 948 reject the profile data and retry enrollment. To allow for this 949 authentication, the PDS SHOULD include the SIP Identity header as 950 specified in [RFC4474]. Exceptions are PDSs that do not serve 951 sensitive profiles, or those in deployments where communication with 952 the PDS in the absence of a mutually authenticated TLS is disallowed. 953 When the SIP Identify header is used, the PDS MUST set the host 954 portion of the AoR in the 'From' header to the Provider's domain. 956 Note that both Server Identity authentication ([RFC2818]) and SIP 957 Identity ([RFC4474] require X.509 certificates. Additionally, the 958 use of TLS and mutual authentication also provides message integrity 959 and privacy between the device and the next-hop entity. When the 960 next-hop entity is a proxy, the Provider will need ensure mutual 961 authentication and integrity between intermediary components such as 962 proxies and PDSs. This is mandatory when a SIPS URI is presented by 963 the device. 965 Authentication of the identity requesting the profile is accomplished 966 by the PDS by using the Digest Authentication mechanism, over TLS. 967 Thus, devices and PDSs MUST implement Digest Authentication specified 968 in [RFC3261], and TLS as specified in [RFC4346]. If the device 969 presents a user AoR, it should be recognized by the network. If not 970 (e.g., discovered or device identities) it may not be known by the 971 PDS (and hence, may not be associated with credentials). If known by 972 the PDS and the notification will result in data specific to the user 973 AoR, the PDS MUST challenge the request using Digest authentication 974 specified in [RFC3261]. If the device successfully responds to the 975 challenge, it is provided the initial notification, which contains 976 the profile data within, or via content indirection. If user 977 authentication fails the PDS MAY refuse enrollment, or provide 978 profile data without the user-specific information. As a note, if 979 the PDS attempts authentication in the absence of an authenticated 980 TLS session between the device and the next-hop entity, it will be 981 ignored by the device. A PDS that does not perform authentication 982 MUST use content indirection to a PCC that supports authentication, 983 integrity protection and privacy for conveying sensitive profile 984 data. 986 5.2.2. Securing Content Retrieval 988 Initial or change notifications following a successful enrollment can 989 provide a device with the requested profile data, or use content 990 indirection to direct it to a PCC that can provide the profile data. 991 This document specifies HTTP and HTTPS as content retrieval 992 protocols. 994 If the profile is provided via content indirection and contains 995 sensitive profile data then the PDS MUST use a HTTPS URI for content 996 indirection. PCCs and devices MUST NOT use HTTP for sensitive 997 profile data. A device MUST authenticate the PCC as specified in 999 [RFC2818], Section 3.1. A device that is being provided with profile 1000 data that contains sensitive data MUST be authenticated using Digest 1001 as specified in [RFC2617], with the exception of a device that is 1002 being bootstrapped for the first time. The resulting mutually 1003 authenticated TLS channel also provides message integrity. 1005 5.2.3. Securing Change Notification 1007 A successful profile enrollment results in an initial notification. 1008 If the device requested enrollment via a SIP subscription with a non- 1009 zero 'Expires' parameter, it can also result in change notifications 1010 for the duration of the subscription. 1012 If the device established TLS with the next-hop entity then any such 1013 notifications SHOULD be sent over the same TLS session by the PDS. 1014 If the TLS session exists, the device MUST ignore any notifications 1015 sent outside the TLS session. If no such TLS session exists, the 1016 device MUST NOT accept any sensitive profile data without verifying 1017 the presence of, and validating, a SIP Identity header. 1019 A PDS that does not support TLS MUST use content indirection to a PCC 1020 that supports authentication and integrity protection for conveying 1021 sensitive profile data. 1023 5.3. Additional Considerations 1025 This section provides additional considerations such as details on 1026 how a device obtains identities and credentials, backoff and retry 1027 methods, guidelines on profile data and additional profile types. 1029 5.3.1. Identities and Credentials 1031 When requesting a profile the device can provide an identity such as 1032 a user AoR. To do so, the device needs to be configured. This can 1033 be accomplished in one of many ways: 1035 Pre-configuration 1037 The device may be pre-configured with identities and associated 1038 credentials, such as a user AoR and digest password. 1040 Out-of-band methods 1042 A device or Provider may provide hardware- or software-based 1043 credentials such as SIM cards or USB drives. 1045 End-user interface 1047 The end-user may be provided with user AoRs and credentials. The 1048 end-user can then configure the device (using a user interface), 1049 or present when required (e.g., IM login screen). 1051 Using this framework 1053 When a device is initialized, even if it has no pre-configured 1054 information, it can request the local-network and device profiles. 1055 In such a case the device profile can provide three kinds of 1056 information: 1057 * Profile data that allows the end-user to communicate with the 1058 device or SIP service provider. The provider can then use any 1059 applicable method (e.g., web portal) to provide the user AoR. 1060 * Profile data that redirects the device to an entity, such as 1061 the PCC, that can provide identity data. As an example, 1062 consider a device that has a X.509 certificate that can be 1063 authenticated by the PCC. In such a case, the PCC can use 1064 HTTPS to provide the user AoR. 1065 * Profile data containing user identity to be used. This can be 1066 used in cases where the device is initialized for the first 1067 time, or after a factory reset, in the device provider's 1068 network. 1070 If a device presents a user AoR in the enrollment request, the PDS 1071 can challenge it. To respond to such authentication challenges, the 1072 device needs to have associated credentials. Thus, any of the 1073 configuration methods indicated above need to provide the user 1074 credentials along with any AoRs. 1076 Additionally, AoRs are typically known by PDSs that serve the domain 1077 indicated by the AoR. Thus, devices can only present the configured 1078 AoRs in the respective domains. An exception is the use of federated 1079 identities. This allows a device to use a user's AoR in multiple 1080 domains. 1082 The configured user AoR and associated credentials can be used in 1083 applicable domains for any of the profile types specified by this 1084 framework. In the absence of the user AoR, the device is not 1085 expected to contain any other credentials. Future enhancements can 1086 specify additional identities and credentials. 1088 5.3.2. Profile Enrollment Request Attempt 1090 A state diagram representing a device requesting any specific profile 1091 defined by this framework is shown in Figure 6. 1093 +------------+ 1094 | Initialize | 1095 +-----+------+ 1096 | 1097 | 1098 V 1099 +-------------+ 1100 | Prepare | 1101 +--------->| Enrollment |<------------------+ 1102 | | Request | | 1103 | +------+------+ | 1104 +------+------+ | | 1105 | Failure | Enroll. Req. prepared | 1106 +-->| Handling & | /Send Req | 1107 | | Delay | | | 1108 | +-------------+ V | 1109 | ^ ^ +-------------+ | 1110 | | | | Await | | 1111 | | +--------+ Enrollment | | 1112 | | Timeout, | acceptance | | 1113 | | non-2xx/- +------+------+ | 1114 | | | | 1115 | Timeout 200 OK/- Enrollment 1116 | /Terminate | Timeout/- 1117 | Enrollment V | 1118 | | +--------------+ | 1119 | | | Enrollment | | 1120 | +------------+ accepted | | 1121 Retries Exceeded |(await NOTIFY)| | 1122 /Retry Enrollment +---+------+---+ | 1123 | | | | 1124 | | | | 1125 | NOTIFY w. Content Ind| | NOTIFY w. Profile | 1126 | /Retrieve Profile | | /Accept Profile | 1127 | +------------+ +------------+ | 1128 | | | | 1129 | V V | 1130 | +------------+ +------------+ | 1131 +-----+ Retrieving | Retrieved | Enrollment +---+ 1132 ,->| Profile +--/Apply Profile-->| Successful | 1133 / | | |(monitoring)|<--. 1134 Timeout +--+---------+ +--+----+----+ : 1135 /Retry ; ^ | : ; 1136 `------' | NOTIFY w. Cont.Ind | `-------' 1137 +---/Retrieve Profile-----+ NOTIFY w. Profile 1138 /Apply Profile 1140 Figure 6: Device State Diagram 1142 As a reminder: 1143 o The timeout for SIP messages is specified by [RFC3261] 1144 o The timeout for profile retrieval using content indirection will 1145 be as specified by profile retrieval protocols employed 1147 In addition, since profile enrollment is a process unique to this 1148 framework, the device MUST follow the enrollment attempt along with 1149 exponential backoff and retry mechanisms as indicated in Figure 7. 1151 Function for Profile Enrollment () 1153 Iteration i=0 1155 Loop: Attempt 1157 Loop: For each SIP Subscription URI 1159 Loop: For each next-hop SIP entity 1161 - Prepare & transmit Enrollment Request 1163 - Await Enrollment Acceptance and initial NOTIFY 1165 + If the profile enrollment is successful 1166 = Exit this function() 1168 + If profile enrollment fails due to an explicit 1169 failure or a timeout as specified in RFC3261 1170 = Continue with this function() 1172 End Loop: Next-hop SIP entity contact 1174 End Loop: SIP Subscription URI formation 1176 (Note: If you are here, profile enrollment did not succeed) 1178 + Is any valid cached profile data available? 1179 = If yes, use it and continue with this function() 1181 + If the enrollment request is for a non-mandatory profile 1182 = then spawn the next profile and continue with this 1183 function() 1185 - Delay for 2^i*(64*T1); -- this is exponential backoff 1187 - increment i; 1189 - If i>8, reset i=8; 1191 End loop: Attempt 1193 End Function() 1195 Figure 7: Profile Enrollment Attempt (pseudo-code) 1197 The pseudo-code above (Figure 7) allows for cached profiles to be 1198 used. However, any cached Local Network profile MUST NOT be used 1199 unless the device can ensure that it is in the same local network 1200 which provided the cached data. This framework does not provide any 1201 procedures for local network recognition. Any cached device and user 1202 profiles MUST only be used in domains that they are associated with. 1203 For example, a cached device profile is used only when the associated 1204 domain matches the current device provider's domain. If a PDS wants 1205 to invalidate a profile it may do so by transmitting a NOTIFY with an 1206 'empty profile' (not to be confused with an empty NOTIFY). A device 1207 receiving such a NOTIFY MUST discard the applicable profile (i.e., it 1208 cannot even store it in the cache). Additionally, if a factory reset 1209 is available and performed on a device, it MUST reset the device to 1210 its initial state prior to any configuration. Specifically, the 1211 device MUST set the device back to the state when it was originally 1212 distributed. 1214 The order of profile enrollment is important. For the profiles 1215 specified in this framework, the device must enroll in the order: 1216 local-network, device and user. The pseudo-code presented earlier 1217 (Figure 7) differentiates between 'mandatory' and 'non-mandatory' 1218 profiles. This distinction is left to profile data definitions. 1220 It is to be noted that this framework does not allow the devices to 1221 inform the PDSs of profile retrieval errors such as invalid data. 1222 Follow-on standardization activities are expected to address this 1223 feature. 1225 5.3.3. Device Types 1227 The examples in this framework tend to associate devices with 1228 entities that are accessible to end-users. However, this is not 1229 necessarily the only type of device that can utilize the specified 1230 Framework. Devices can be entities such as SIP Phones or soft 1231 clients, with or without user interfaces (that allow for device 1232 Configuration), entities in the network that do not directly 1233 communicate with any users (e.g., gateways, media servers, etc) or 1234 network infrastructure elements e.g., SIP servers). 1236 5.3.4. Profile Data 1238 This framework does not specify the contents for any profile type. 1239 Follow-on standardization activities are expected to address profile 1240 contents. However, the framework provides the following requirements 1241 and recommendations for profile data definitions: 1243 o The device profile type SHOULD specify parameters to configure the 1244 identities and credentials. These parameters may be optional or 1245 mandatory and will be used for dynamically configuring devices 1246 that initialize in a network without any pre-configuration. 1247 o Each profile MUST clearly identify if it may contain any sensitive 1248 data. Such profiles MUST also identify the data elements that are 1249 considered sensitive, i.e., data that cannot be compromised. As 1250 an example, a device profile definition may identify itself as 1251 containing sensitive data and indicate data such as device 1252 credentials to be sensitive. 1253 o When the device receives multiple profiles, the contents of each 1254 profile type SHOULD only contain data relevant to the entity it 1255 represents. As an example, consider a device that obtains all the 1256 defined profiles. Information pertaining to the local network is 1257 contained in the 'local-network' profile and not the 'user' 1258 profile. This does not preclude relevant data about a different 1259 entity from being included in a profile type, e.g., the 'device' 1260 profile type may contain information about the users allowed to 1261 access services via the device. A profile may also contain 1262 starting information to obtain subsequent Profiles. 1263 o Data overlap SHOULD be avoided across profile types, unless 1264 necessary. If data overlap is present, prioritization of the data 1265 is left to data definitions. As an example, the device profile 1266 may contain the list of codecs to be used by the device and the 1267 user Profile (for a user on the device) may contain the codecs 1268 preferred by the user. Thus, the same data (usable codecs) is 1269 present in two profiles. However, the data definitions may 1270 indicate that to function effectively, any codec chosen for 1271 communication needs to be present in both the profiles. 1273 5.3.5. Profile Data Frameworks 1275 The framework specified in this document does not address profile 1276 data representation, storage or retrieval protocols. It assumes that 1277 the PDS has a PCC based on existing or other Profile Data Frameworks. 1279 While this framework does not impose specific constraints on any such 1280 framework, it does allow for the propagation of profile content to 1281 the PDS (specifically the PCC) from a network element or the device. 1282 Thus, Profile Data or Retrieval frameworks used in conjunction with 1283 this framework MAY consider techniques for propagating incremental, 1284 atomic changes to the PDS. One means for propagating changes to a 1285 PDS is defined in XCAP ([RFC4825]). 1287 5.3.6. Additional Profile Types 1289 This document specifies three profile types: local-network, device 1290 and user. However, there may be use cases for additional profile 1291 types. e.g., profile types for application specific profile data or 1292 to provide enterprise-specific policies. Definition of such 1293 additional profile types is not prohibited, but considered out of 1294 scope for this document. Such profile definitions MUST specify the 1295 order of retrieval with respect to all the other profiles such as the 1296 local-network, device and user profile types defined in this 1297 document. 1299 5.3.7. Deployment considerations 1301 The framework defined in this document was designed to address 1302 various deployment considerations, some of which are highlighted 1303 below. 1305 Provider relationships: 1306 o The local network provider and the SIP service provider can often 1307 be different entities, with no administrative or business 1308 relationship with each other. 1309 o There may be multiple SIP service providers involved, one for each 1310 service that a user subscribes to (telephony service, instant 1311 messaging, etc.); this Framework does not specify explicit 1312 behavior in such a scenario, but it does not prohibit its usage 1313 either. 1314 o Each user accessing services via the same device may subscribe to 1315 different sets of services, from different Service Providers. 1317 User-device relationship: 1318 o The relationship between devices and users can be many-to-many 1319 (e.g., a particular device may allow for many users to obtain 1320 subscription services through it, and individual users may have 1321 access to multiple devices). 1322 o Each user may have different preferences for use of services, and 1323 presentation of those services in the device user interface. 1324 o Each user may have different personal information applicable to 1325 use of the device, either as related to particular services, or 1326 independent of them. 1328 5.4. Usage of Outbound 1330 PDSs that support devices behind NATs, and devices that can be behind 1331 NATs can use procedures specified in [I-D.ietf-sip-outbound]. The 1332 Outbound proxies can be configured or discovered. Clients that 1333 support such behavior MUST include the 'outbound' option-tag in a 1334 Supported header field value, and add the "ob" parameter as specified 1335 in [I-D.ietf-sip-outbound] within the SIP SUBSCRIBE for profile 1336 enrollment. 1338 6. Event Package Definition 1340 The framework specified in this document proposes and specifies a new 1341 SIP Event Package as allowed by [RFC3265]. The purpose is to allow 1342 for devices to subscribe to specific profile types with PDSs and for 1343 the PDSs to notify the devices with the profile data or content 1344 indirection information. 1346 The requirements specified in [RFC3265] apply to this package. The 1347 following sub-sections specify the Event Package description and the 1348 associated requirements. The framework requirements are defined in 1349 Section 5. 1351 6.1. Event Package Name 1353 The name of this package is "ua-profile". This value appears in the 1354 Event header field present in SUBSCRIBE and NOTIFY requests for this 1355 package as defined in [RFC3265]. 1357 6.2. Event Package Parameters 1359 This package defines the following new parameters for the event 1360 header: 1361 "profile-type", "vendor", "model", "version", and "effective-by" 1363 The following rules apply: 1364 o All the new parameters, with the exception of the "effective-by" 1365 parameter MUST only be used in SUBSCRIBE requests and ignored if 1366 they appear in NOTIFY requests. 1367 o The "effective-by" parameter is for use in NOTIFY requests only 1368 and MUST be ignored if it appears in SUBSCRIBE requests. 1370 The semantics of these new parameters are specified in the following 1371 sub-sections. 1373 6.2.1. profile-type 1375 The "profile-type" parameter is used to indicate the token name of 1376 the profile type the user agent wishes to obtain and to be notified 1377 of subsequent changes. This document defines three logical types of 1378 profiles and their token names. They are as follows: 1380 local-network: specifying the "local-network" type profile indicates 1381 the desire for profile data specific to the local network. 1383 device: specifying the "device" type profile(s) indicates the desire 1384 for the profile data and profile change notification that is 1385 specific to the device or user agent. 1387 user: Specifying "user" type profile indicates the desire for the 1388 profile data and profile change notification specific to the user. 1390 The profile type is identified in the Event header parameter: 1391 "profile-type". A separate SUBSCRIBE dialog is used for each profile 1392 type. Thus, the subscription dialog on which a NOTIFY arrives 1393 implies which profile's data is contained in, or referred to, by the 1394 NOTIFY message body. The Accept header of the SUBSCRIBE request MUST 1395 include the MIME types for all profile content types for which the 1396 subscribing user agent wishes to retrieve profiles, or receive change 1397 notifications. 1399 In the following syntax definition using ABNF, EQUAL and token are 1400 defined in [RFC3261]. It is to be noted that additional profile 1401 types may be defined in subsequent documents. 1403 Profile-type = "profile-type" EQUAL profile-value 1404 profile-value = profile-types / token 1405 profile-types = "device" / "user" / "local-network" 1407 The "device", "user" or "local-network" token in the profile-type 1408 parameter may represent a class or set of profile properties. 1409 Follow-on standards defining specific profile contents may find it 1410 desirable to define additional tokens for the profile-type parameter. 1411 Also, additional content types may be defined along with the profile 1412 formats that can be used in the Accept header of the SUBSCRIBE to 1413 filter or indicate what data sets of the profile are desired. 1415 6.2.2. vendor, model and version 1417 The "vendor", "model" and "version" parameter values are tokens 1418 specified by the implementer of the user agent. These parameters 1419 MUST be provided in the SUBSCRIBE request for all profile types. The 1420 implementer SHOULD use their DNS domain name (e.g., example.com) as 1421 the value of the "vendor" parameter so that it is known to be unique. 1422 These parameters are useful to the PDS to affect the profiles 1423 provided. In some scenarios it is desirable to provide different 1424 profiles based upon these parameters. e.g., feature property X in a 1425 profile may work differently on two versions of the same user agent. 1426 This gives the PDS the ability to compensate for or take advantage of 1427 the differences. In the following ABNF defining the syntax, EQUAL 1428 and quoted-string are defined in [RFC3261]. 1430 Vendor = "vendor" EQUAL quoted-string 1431 Model = "model" EQUAL quoted-string 1432 Version = "version" EQUAL quoted-string 1434 6.2.3. effective-by parameter 1436 The "effective-by" parameter in the Event header of the NOTIFY 1437 request specifies the maximum number of seconds before the user agent 1438 must attempt to make the new profile effective. The "effective-by" 1439 parameter MAY be provided in the NOTIFY request for any of the 1440 profile types. A value of 0 (zero) indicates that the subscribing 1441 user agent must attempt to make the profiles effective immediately 1442 (despite possible service interruptions). This gives the PDS the 1443 power to control when the profile is effective. This may be 1444 important to resolve an emergency problem or disable a user agent 1445 immediately. The "effective-by" parameter is ignored in all messages 1446 other than the NOTIFY request. In the following ABNF, EQUAL and 1447 DIGIT are defined in [RFC3261]. 1449 Effective-By = "effective-by" EQUAL 1*DIGIT 1451 6.2.4. Summary of event parameters 1453 The following are example Event headers which may occur in SUBSCRIBE 1454 requests. These examples are not intended to be complete SUBSCRIBE 1455 requests. 1457 Event: ua-profile;profile-type=device; 1458 vendor="vendor.example.com";model="Z100";version="1.2.3" 1460 Event: ua-profile;profile-type=user; 1461 vendor="premier.example.com";model="trs8000";version="5.5" 1463 The following are example Event headers which may occur in NOTIFY 1464 requests. These example headers are not intended to be complete 1465 SUBSCRIBE requests. 1467 Event: ua-profile;effective-by=0 1469 Event: ua-profile;effective-by=3600 1470 The following table shows the use of Event header parameters in 1471 SUBSCRIBE requests for the three profile types: 1473 profile-type || device | user | local-network 1474 ============================================= 1475 vendor || m | m | m 1476 model || m | m | m 1477 version || m | m | m 1478 effective-by || | | 1480 m - mandatory 1481 s - SHOULD be provided 1482 o - optional 1484 Non-specified means that the parameter has no meaning and should be 1485 ignored. 1487 The following table shows the use of Event header parameters in 1488 NOTIFY requests for the three profile types: 1490 profile-type || device | user | local-network 1491 ============================================= 1492 vendor || | | 1493 model || | | 1494 version || | | 1495 effective-by || o | o | o 1497 6.3. SUBSCRIBE Bodies 1499 This package defines no use of the SUBSCRIBE request body. If 1500 present, it SHOULD be ignored. The exception being future 1501 enhancements to the framework which may specify a use for the 1502 SUBSCRIBE request body. 1504 6.4. Subscription Duration 1506 The duration of a subscription is specific to SIP deployments and no 1507 specific recommendation is made by this Event Package. If absent, a 1508 value of 86400 seconds (24 hours; 1 day) is RECOMMENDED since the 1509 presence (or absence) of a device subscription is not time critical 1510 to the regular functioning of the PDS. 1512 It is to be noted that a one-time fetch of a profile, without ongoing 1513 subscription, can be accomplished by setting the 'Expires' parameter 1514 to a value of Zero, as specified in [RFC3265]. 1516 6.5. NOTIFY Bodies 1518 The framework specifying the Event Package allows for the NOTIFY body 1519 to contain the profile data, or a pointer to the profile data using 1520 content indirection. For profile data delivered via content 1521 indirection, i.e., a pointer to a PCC, then the Content-ID MIME 1522 header, as described in [RFC4483] MUST be used for each Profile 1523 document URI. At a minimum, the "http:" and "https:" URI schemes 1524 MUST be supported; other URI schemes MAY be supported based on the 1525 Profile Data Frameworks (examples include FTP [RFC0959], HTTP 1526 [RFC2616], HTTPS [RFC2818], LDAP [RFC4510] and XCAP [RFC4825] ). 1528 A non-empty NOTIFY body MUST include a MIME type specified in the 1529 'Accept' header of the SUBSCRIBE. Further, if the Accept header of 1530 the SUBSCRIBE included the MIME type message/external-body 1531 (indicating support for content indirection) then the PDS MAY use 1532 content indirection in the NOTIFY body for providing the profiles. 1534 6.6. Notifier Processing of SUBSCRIBE Requests 1536 A successful SUBSCRIBE request results in a NOTIFY with either 1537 profile contents or a pointer to it (via Content Indirection). The 1538 SUBSCRIBE SHOULD be either authenticated, or transmitted over an 1539 integrity protected SIP communications channel. Exceptions include 1540 cases where the identity of the Subscriber is unknown and the 1541 Notifier is configured to accept such requests. 1543 The Notifier MAY also authenticate SUBSCRIBE messages even if the 1544 NOTIFY is expected to only contain a pointer to profile data. 1545 Securing data sent via Content Indirection is covered in Section 9. 1547 If the profile type indicated in the "profile-type" Event header 1548 parameter is unavailable or the Notifier is configured not to provide 1549 it, the Notifier SHOULD return a 404 response to the SUBSCRIBE 1550 request. If the specific user or device is unknown, the Notifier MAY 1551 either accept or reject the subscription. 1553 6.7. Notifier Generation of NOTIFY Requests 1555 As specified in [RFC3265], the Notifier MUST always send a NOTIFY 1556 request upon accepting a subscription. If the device or user is 1557 unknown and the Notifier chooses to accept the subscription, the 1558 Notifier MAY either respond with profile data (e.g., default profile 1559 data) or provide no profile information (i.e. no body or content 1560 indirection). 1562 If the URI in the SUBSCRIBE request is a known identity and the 1563 requested profile information is available (i.e. as specified in the 1564 profile-type parameter of the Event header), the Notifier SHOULD send 1565 a NOTIFY with profile data. Profile data MAY be sent as profile 1566 contents or via Content Indirection (if the content indirection MIME 1567 type was included in the Accept header). The Notifier MUST NOT use 1568 any scheme that was not indicated in the "schemes" Contact header 1569 field. 1571 The Notifier MAY specify when the new profiles must be made effective 1572 by the Subscriber by specifying a maximum time in seconds (zero or 1573 more) in the "effective-by" event header parameter. 1575 If the SUBSCRIBE was received over an integrity protected SIP 1576 communications channel, the Notifier SHOULD send the NOTIFY over the 1577 same channel. 1579 6.8. Subscriber Processing of NOTIFY Requests 1581 A Subscriber to this event package MUST adhere to the NOTIFY request 1582 processing behavior specified in [RFC3265]. If the Notifier 1583 indicated an effective time (using the "effective-by" Event Header 1584 parameter), the Subscriber SHOULD attempt to make the profiles 1585 effective within the specified time. Exceptions include deployments 1586 that prohibit such behavior in certain cases (e.g., emergency 1587 sessions are in progress). When profile data cannot be applied 1588 within the recommended timeframe and this affects device behavior, 1589 any actions to be taken SHOULD be defined by the profile data 1590 definitions. By default, the Subscriber is RECOMMENDED to make the 1591 profiles effective as soon as possible. 1593 When accepting content indirection, the Subscriber MUST always 1594 support "http:" or "https:" and be prepared to accept NOTIFY messages 1595 with those URI schemes. The Subscriber wishes to support alternative 1596 URI schemes it MUST be indicated in the "schemes" Contact header 1597 field parameter as defined in [RFC4483]. The Subscriber MUST also be 1598 prepared to receive a NOTIFY request with no body. The subscriber 1599 MUST NOT reject the NOTIFY request with no body. The subscription 1600 dialog MUST NOT be terminated by a NOTIFY with no body. 1602 6.9. Handling of Forked Requests 1604 This Event package allows the creation of only one dialog as a result 1605 of an initial SUBSCRIBE request as described in section 4.4.9 of 1606 [RFC3265]. It does not support the creation of multiple 1607 subscriptions using forked SUBSCRIBE requests. 1609 6.10. Rate of Notifications 1611 The rate of notifications for the profiles in this framework is 1612 deployment specific, but expected to be infrequent. Hence, the Event 1613 Package specification does not specify a throttling or minimum period 1614 between NOTIFY requests 1616 6.11. State Agents 1618 State agents are not applicable to this Event Package. 1620 7. Examples 1622 This section provides examples along with sample SIP message bodies 1623 relevant to this framework. Both the examples are derived from a 1624 snapshot of Section 4.1, specifically the request for the device 1625 profile. The examples are purely informative and in case of 1626 conflicts with the framework or protocols used for illustration, the 1627 latter should be deemed normative. 1629 7.1. Example 1: Device requesting profile 1631 This example illustrates the detailed message flows between the 1632 device and the SIP Service Provider's network for requesting and 1633 retrieving the profile (the flow uses the device profile as an 1634 example). 1636 The following are assumed for this example: 1638 o Device is assumed to have established local network connectivity; 1639 NAT and Firewall considerations are assumed to have been addressed 1640 by the SIP Service Provider. 1641 o Examples are snapshots only and do not illustrate all the 1642 interactions between the device and the Service Provider's network 1643 (and none between the entities in the SIP Service Provider's 1644 network). 1645 o All SIP communication with the SIP Service Provider happens via a 1646 SIP Proxy. 1647 o HTTP over TLS is assumed to be the Content Retrieval method used 1648 (any suitable alternative can be used as well). 1650 The flow diagram and an explanation of the messages follow. 1652 +----------------------+ 1653 +--------+ | SIP Service Provider | 1654 | Device | | | 1655 |(SIP UA)| | SIP PDS HTTP | 1656 +--------+ | PROXY Server | 1657 | | 1658 +----------------------+ 1659 | | | | 1660 | | | | 1661 | SUBSCRIBE | | | 1662 (SReq)|--------device profile--------->| | | 1663 | |------>| | 1664 | |200 OK | | 1665 | 200 OK |<------| | 1666 (SRes)|<-------------------------------| | | 1667 | | | | 1668 | | NOTIFY| | 1669 | NOTIFY (Content Indirection)|<------| | 1670 (NTFY)|<-------------------------------| | | 1671 | 200 OK | | | 1672 (NRes)|------------------------------->|200 OK | | 1673 | |------>| | 1674 | | 1675 | | 1676 | | 1677 |<<<<<<<<<<<<< TLS establishment >>>>>>>>>>>>>| 1678 | | 1679 | HTTP Request | 1680 (XReq)|---------------------------------------------->| 1681 | | 1682 | HTTP Response | 1683 (XRes)|<----------------------------------------------| 1684 | | 1686 (SReq) 1688 the device transmits a request for the 'device' profile using the 1689 SIP SUBSCRIBE utilizing the Event Package specified in this 1690 framework. 1692 * Note: Some of the header fields (e.g., SUBSCRIBE, Event, via) 1693 are continued on a separate line due to format constraints of 1694 this document. 1696 SUBSCRIBE sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB 1697 @example.com SIP/2.0 1698 Event: ua-profile;profile-type=device;vendor="vendor.example.net"; 1699 model="Z100";version="1.2.3"; 1700 From: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB 1701 @example.com;tag=1234 1702 To: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com 1703 Call-ID: 3573853342923422@192.0.2.44 1704 CSeq: 2131 SUBSCRIBE 1705 Contact: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB 1706 @example.com 1707 ;+sip.instance="" 1708 ;schemes="http,https" 1709 Via: SIP/2.0/TCP 192.0.2.41; 1710 branch=z9hG4bK6d6d35b6e2a203104d97211a3d18f57a 1711 Accept: message/external-body, application/x-z100-device-profile 1712 Content-Length: 0 1714 (SRes) 1716 the SUBSCRIBE request is received by a SIP Proxy in the Service 1717 Provider's network which transmits it to the PDS. The PDS accepts 1718 the response and responds with a 200 OK 1719 * Note: The device and the SIP proxy may have established a 1720 secure communications channel (e.g., TLS). 1722 (NTFY) 1724 subsequently, the PDS transmits a SIP NOTIFY message indicating 1725 the profile location 1726 * Note: Some of the fields (e.g., content-type) are continued on 1727 a separate line due to format constraints of this document. 1729 NOTIFY sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB 1730 @192.0.2.44 SIP/2.0 1731 Event: ua-profile;effective-by=3600 1732 From: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com 1733 ;tag=abca 1734 To: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com 1735 ;tag=1231 1736 Call-ID: 3573853342923422@192.0.2.44 1737 CSeq: 322 NOTIFY 1738 Via: SIP/2.0/UDP 192.0.2.3; 1739 branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d0 1740 MIME-Version: 1.0 1741 Content-Type: message/external-body; access-type="URL"; 1742 expiration="Mon, 01 Jan 2010 09:00:00 UTC"; 1743 URL="http://example.com/z100-000000000000.html"; 1744 size=9999; 1745 hash=10AB568E91245681AC1B 1747 Content-Type: application/x-z100-device-profile 1748 Content-ID: <39EHF78SA@example.com> 1749 . 1750 . 1751 . 1753 (NRes) 1755 Device accepts the NOTIFY message and responds with a 200 OK 1757 (XReq) 1759 once the necessary secure communications channel is established, 1760 the device sends an HTTP request to the HTTP server indicated in 1761 the NOTIFY 1763 (XRes) 1765 the HTTP server responds to the request via a HTTP response 1766 containing the profile contents 1768 7.2. Example 2: Device obtaining change notification 1770 The following example illustrates the case where a user (X) is 1771 simultaneously accessing services via two different devices (e.g., 1772 Multimedia entities on a PC and PDA) and has access to a user 1773 Interface (UI) that allows for changes to the user profile. 1775 The following are assumed for this example: 1776 o The devices (A & B) obtain the necessary profiles from the same 1777 SIP Service Provider. 1778 o The SIP Service Provider also provides a user Interface (UI) that 1779 allows the user to change preferences that impact the user 1780 profile. 1782 The flow diagram and an explanation of the messages follow. 1783 o Note: The example only shows retrieval of user X's profile, but it 1784 may request and retrieve other profiles (e.g., local-network, 1785 Device). 1787 ----- ----- 1788 |User |_________| UI* | * = User Interface 1789 | X | | | 1790 ----- ----- 1791 / \ 1792 / \ 1793 / \ +----------------------+ 1794 +--------+ +--------+ | SIP Service Provider | 1795 | Device | | Device | | | 1796 | A | | B | | SIP PDS HTTP | 1797 +--------+ +--------+ | PROXY Server | 1798 +----------------------+ 1799 | | | | 1800 | | | | 1801 (A-EX)|<=Enrolls for User X's profile=>|<=====>| | 1802 | | | | 1803 | | 1804 (A-RX)|<===Retrieves User X's profile================>| 1805 | | 1806 | | | | | 1807 | | Enrolls for | | | 1808 | (B-EX)|<== User X's ==>|<=====>| | 1809 | | profile | | | 1810 | | | | | 1811 | | | 1812 | (B-RX)|<= Retrieves User X's profile=>| 1813 | | 1814 | | | 1815 | (HPut)|---------------------->| 1816 | | | 1817 | (HRes)|<----------------------| 1818 | | 1819 | | | | 1820 | | NOTIFY| | 1821 | NOTIFY |<------| | 1822 (A-NT)|<-------------------------------| | | 1823 | 200 OK | | | 1824 (A-RS)|------------------------------->|200 OK | | 1825 | |------>| | 1826 | | 1827 | | | NOTIFY| | 1828 | | NOTIFY |<------| | 1829 | (B-NT)|<---------------| | | 1830 | | 200 OK | | | 1831 | (B-RS)|--------------->|200 OK | | 1832 | | |------>| | 1833 | | 1834 | | 1835 (A-RX)|<===Retrieves User X's profile================>| 1836 | | 1837 | | | 1838 | | | 1839 | (B-RX)|<= Retrieves User X's profile=>| 1840 | | | 1842 (A-EX) Device A discovers, enrolls and obtains notification related 1843 to user X's profile. 1844 (A-RX) Device A retrieves user X's profile. 1845 (B-EX) Device B discovers, enrolls and obtains notification related 1846 to user X's profile. 1847 (B-RX) Device B retrieves user X's profile. 1848 (HPut) Changes affected by the user via the user Interface (UI) are 1849 uploaded to the HTTP Server. 1850 * Note: The UI itself can act as a device and subscribe to user 1851 X's profile. This is not the case in the example shown. 1852 (HRes) Changes are accepted by the HTTP server. 1853 (A-NT) PDS transmits a NOTIFY message to device A indicating the 1854 changed profile. A sample message is shown below: 1855 Note: Some of the fields (e.g., Via) are continued on a 1856 separate line due to format constraints of this document. 1858 NOTIFY sip:userX@192.0.2.44 SIP/2.0 1859 Event: ua-profile;effective-by=3600 1860 From: sip:userX@sip.example.net;tag=abcd 1861 To: sip:userX@sip.example.net.net;tag=1234 1862 Call-ID: 3573853342923422@192.0.2.44 1863 CSeq: 322 NOTIFY 1864 Via: SIP/2.0/UDP 192.0.2.3; 1865 branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d1 1866 MIME-Version: 1.0 1867 Content-Type: message/external-body; access-type="URL"; 1868 expiration="Mon, 01 Jan 2010 09:00:00 UTC"; 1869 URL="http://www.example.com/user-x-profile.html"; 1870 size=9999; 1871 hash=123456789AAABBBCCCDD 1872 . 1873 . 1874 . 1876 (A-RS) Device A accepts the NOTIFY and sends a 200 OK 1877 (B-NT) PDS transmits a NOTIFY message to device B indicating the 1878 changed profile. A sample message is shown below: 1879 Note: Some of the fields (e.g., Via) are continued on a 1880 separate line due to format constraints of this document. 1882 NOTIFY sip:userX@192.0.2.43 SIP/2.0 1883 Event: ua-profile;effective-by=3600 1884 From: sip:userX@sip.example.net;tag=abce 1885 To: sip:userX@sip.example.net.net;tag=1235 1886 Call-ID: 3573853342923422@192.0.2.43 1887 CSeq: 322 NOTIFY 1888 Via: SIP/2.0/UDP 192.0.2.3; 1889 branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d2 1890 MIME-Version: 1.0 1891 Content-Type: message/external-body; access-type="URL"; 1892 expiration="Mon, 01 Jan 2010 09:00:00 UTC"; 1893 URL="http://www.example.com/user-x-profile.html"; 1894 size=9999; 1895 hash=123456789AAABBBCCCDD 1896 . 1897 . 1898 . 1900 (B-RS) Device B accepts the NOTIFY and sends a 200 OK 1901 (A-RX) Device A retrieves the updated profile pertaining to user X 1902 (B-RX) Device B retrieves the updated profile pertaining to user X 1904 8. IANA Considerations 1906 There are two IANA considerations associated with this document, SIP 1907 Event Package and SIP configuration profile types. These are 1908 outlined in the following sub-sections. 1910 8.1. SIP Event Package 1912 This specification registers a new event package as defined in 1913 [RFC3265]. The following information required for this registration: 1915 Package Name: ua-profile 1916 Package or Template-Package: This is a package 1917 Published Document: RFC XXXX (Note to RFC Editor: Please fill in 1918 XXXX with the RFC number of this specification) 1919 Persons to Contact: Daniel Petrie dan.ietf AT SIPez DOT com, 1920 sumanth@cablelabs.com 1921 New event header parameters: profile-type, vendor, model, version, 1922 effective-by (the profile-type parameter has predefined values. 1923 The new event header parameters do not) 1924 The following table illustrates the additions to the IANA SIP Header 1925 Field Parameters and Parameter Values: (Note to RFC Editor: Please 1926 fill in XXXX with the RFC number of this specification) 1928 Predefined 1929 Header Field Parameter Name Values Reference 1930 ---------------------------- --------------- --------- --------- 1931 Event profile-type Yes [RFCXXXX] 1932 Event vendor No [RFCXXXX] 1933 Event model No [RFCXXXX] 1934 Event version No [RFCXXXX] 1935 Event effective-by No [RFCXXXX] 1937 8.2. Registry of SIP configuration profile types 1939 This document requests IANA to register new SIP configuration profile 1940 types at http://www.iana.org/assignments/sip-parameters under "SIP 1941 Configuration Profile Types". 1943 SIP configuration profile types allocations fall under the category 1944 "Specification Required", as explained in "Guidelines for Writing an 1945 IANA Considerations Section in RFCs" ([RFC2434]). 1947 Registrations with the IANA MUST include a the profile type, and a 1948 published document which describes its purpose and usage. 1950 As this document specifies three SIP configuration profile types, the 1951 initial IANA registration will contain the information shown in the 1952 table below. It also demonstrates the type of information maintained 1953 by the IANA. 1955 Profile Type Reference 1956 -------------- --------- 1957 local-network [RFCXXXX] 1958 device [RFCXXXX] 1959 user [RFCXXXX] 1961 CONTACT: 1962 ------- 1963 sumanth@cablelabs.com 1964 Daniel Petrie dan.ietf AT SIPez DOT com 1966 Note to RFC editor: Please replace RFCXXXX with the RFC number 1967 assigned to this document. 1969 9. Security Considerations 1971 The framework specified in this document enables profile data 1972 delivery to devices. It specifies profile delivery stages, an event 1973 package and several profile types. 1975 There are three stages: Enrollment, Content Retrieval, and Change 1976 Notification. 1978 +------+ +-----+ 1979 | | | | 1980 |Device| | PNC | 1981 | | | | 1982 +------+ +-----+ 1983 | | 1984 | Profile Enrollment | 1985 |---------------------->| 1986 | | 1987 | Initial Notification | 1988 |<----------------------| 1989 | | 1991 +------+ +-----+ 1992 | | | | 1993 |Device| | PNC | 1994 | | | | 1995 +------+ +-----+ 1996 | | 1997 | Profile Enrollment | 1998 |---------------------->| 1999 | | 2000 | Change Notification | 2001 |<----------------------| 2002 | | 2004 +------+ +-----+ 2005 | | | | 2006 |Device| | PCC | 2007 | | | | 2008 +------+ +-----+ 2009 | | 2010 | Profile Request | (When content 2011 |---------------------->| indirection 2012 | | is used) 2013 | Profile Response | 2014 |<----------------------| 2015 | | 2017 PNC = Profile Notification Component 2018 PCC = Profile Content Component 2019 Figure 23: Profile Delivery Stages 2021 Enrollment allows a device to request a profile. To transmit the 2022 request the device relies on configured, cached or discovered data. 2023 Such data includes provider domain names, identities, and 2024 credentials. The device either uses configured Outbound proxies or 2025 discoveries the next-hop entity using [RFC3263] that can result in a 2026 SIP proxy or the PDS. It then transmits the request, after 2027 establishing a TLS session if required. If obtained via a SIP proxy, 2028 the Request-URI is used to route it to a PDS (via an authoritative 2029 SIP proxy, if required). 2031 When a PDS receives the enrollment request, it can either challenge 2032 the presented identity (if any) or admit the enrollment. 2033 Authorization then decides if the enrollment is accepted. If 2034 accepted, the PDS sends an initial notification that contains either 2035 the profile data, or content indirection information. The profile 2036 data can contain information specific to an entity (such as the 2037 device or a user) and may contain sensitive information (such as 2038 credentials). Compromise of such data can lead to threats such as 2039 impersonation attacks (establishing rogue sessions), theft of service 2040 (if services are obtainable), and zombie attacks. Even if the 2041 profile data is provided using content indirection, PCC information 2042 within the notification can lead to threats such as denial of service 2043 attacks (rogue devices bombard the PCC with requests for a specific 2044 profile) and attempts to modify erroneous data onto the PCC (since 2045 the location and format may be known). It is also important for the 2046 device to ensure the authenticity of the PNC since impersonation of 2047 the SIP service provider can lead to Denial of Service, Man-in-the- 2048 Middle attacks, etc. 2050 Profile content retrieval allows a device to retrieve profile data 2051 from a PCC. This communication is accomplished using one of many 2052 profile delivery protocols or frameworks, such as HTTP or HTTPS as 2053 specified in this document. However, since the profile data returned 2054 is subject to the same considerations as that sent via profile 2055 notification, the same threats exist. 2057 Profile-specific considerations follow. 2059 9.1. Local-network profile 2061 A local network may or may not (e.g., home router) support local- 2062 network profiles as specified in this framework. Even if supported, 2063 the PDS may only be configured with a generic local-network profile 2064 that is provided to every device capable of accessing the network. 2065 Such a PDS may not implement any authentication requirements or TLS. 2067 Alternatively, certain deployments may require the entities - device 2068 and the PDS - to mutually authenticate prior to profile enrollment. 2069 Such networks may pre-configure user identities to the devices and 2070 allow user-specific local-network profiles. In such networks the PDS 2071 will contain X.509 certificates and support TLS, and the devices are 2072 pre-configured with user identities, credentials and implement TLS. 2074 This framework supports both use cases and variations in-between. 2075 However, devices obtaining local-network profiles from an 2076 unauthenticated PDS are cautioned against potential MiM or PDS 2077 impersonation attacks. This framework requires that a device reject 2078 sensitive data, such as credentials, from unauthenticated local- 2079 network sources (exceptions are noted). It also prohibits devices 2080 from responding to authentication challenges from unauthenticated 2081 PDSs. Responding to unauthenticated challenges allows for dictionary 2082 attacks that can reveal weak passwords. 2084 If deployments prefer devices to obtain profiles only from pre- 2085 configured domains (e.g., partner networks), they MAY require such 2086 devices to establish TLS prior to obtaining the local-network 2087 profile. 2089 The use of SIP Identity is useful in cases when TLS is not used but 2090 the device still obtains a profile (e.g., the local-network profile). 2091 In such cases the device provider, or the user, can use the SIP 2092 Identity header to verify the source of the local-network profile. 2093 However, the presence of the header does not guarantee the validity 2094 of the data. It verifies the source and confirms data integrity, but 2095 the data obtained from an undesired source may still be invalid 2096 (e.g., it can be invalid or contain malicious content). 2098 9.2. Device profile 2100 Device profiles deal with device-specific configuration. They may be 2101 provided to unknown devices that are attempting to obtaining profiles 2102 for purposes of trials and self-subscription to SIP services (not to 2103 be confused with [RFC3265]), emergency services 2104 ([I-D.ietf-ecrit-phonebcp]), or to devices that are known by the PDS. 2105 Devices that are not aware of any device providers (i.e., no cached 2106 or configured information) will have to discover a PDS in the network 2107 they connect to. In such a case the discovered information may lead 2108 them to a PDS that provides enough profile data to enable device 2109 operation. This configuration can also provide a user AoR that can 2110 be used in the local-network and credentials (temporary or long-term) 2111 that will be used for future communication with the network. This 2112 may enable the device to communicate with a device provider who 2113 allows for self-subscription (e.g., web interface, interactive voice 2114 response or customer service representative). It may also allow the 2115 device a choice of device providers and allow the end-user to choose 2116 one. It is to be noted that such devices are at the mercy of the 2117 network they connect to initially. If they are initialized in a 2118 rogue network, or get hijacked by a rogue PDS, the end-user may be 2119 left without desired device operation, or worse unwanted operation. 2120 To mitigate such factors the device provider may communicate 2121 temporary credentials (PINs that can be entered via an interface) or 2122 permanent credentials (e.g., a USB device) to the end-user for 2123 connectivity. If such methods are used the large-entropy credentials 2124 MUST be used, or quickly replaced with such, to minimize the impact 2125 of dictionary attacks. Future enhancements to this framework may 2126 specify device capabilities that allow for mutual authentication 2127 without pre-configuration (e.g., X.509 certificates using PKI). 2129 Once a device is associated with a device provider (either 2130 dynamically or via pre-configuration using a user interface or prior 2131 to distribution), the device profile is vital to device operation. 2132 This is because the device profile can contain important operational 2133 information such as users that are to be allowed access (white-list 2134 or black-list), user credentials (if required) and other sensitive 2135 information. Thus, it is also necessary to ensure that the device 2136 profile is not obtained via an unauthenticated source or tampered 2137 during transit. Thus the framework requires that devices supporting 2138 any sensitive device profiles establish next-hop authenticated TLS 2139 connections prior to device enrollment. However, given the 2140 importance of the device profile it also allows for profile requests 2141 in cases where the PDS does not implement TLS. It also allows the 2142 PDSs to perform authentication without requiring TLS. However, this 2143 leaves the communication open to MiM attacks and SHOULD be avoided. 2144 Additionally any credential used SHOULD be of sufficiently large- 2145 entropy to prevent dictionary attacks. Devices SHOULD use the 2146 'cnonce' parameter ([RFC2617]) to thwart "offline" dictionary 2147 attacks. 2149 9.3. User profile 2151 Devices can only request user profiles for users that are known by a 2152 SIP service provider. Thus, PDSs are prohibited from accepting user 2153 profile enrollment requests for users that are unknown in the 2154 network. If the user AoR is a SIPS URI then the device is required 2155 to establish a next-hop authenticated TLS session. This framework 2156 requires this for profiles with sensitive data. If it is a SIP URI, 2157 then the device is still recommended to attempt TLS establishment to 2158 ensure protection against rogue PDSs. Further, the PDS will 2159 authenticate requests prior to accepting profile enrollment requests 2160 that can result in sensitive data. A mutually authenticated TLS 2161 channel provides message integrity and privacy. 2163 10. Acknowledgements 2165 The author appreciates all those who contributed and commented on the 2166 many iterations of this document. Detailed comments were provided by 2167 the following individuals: Jonathan Rosenberg from Cisco, Henning 2168 Schulzrinne from Columbia University, Cullen Jennings from Cisco, 2169 Rohan Mahy from Plantronics, Rich Schaaf from Pingtel, Volker Hilt 2170 from Bell Labs, Adam Roach of Estacado Systems, Hisham Khartabil from 2171 Telio, Henry Sinnreich from MCI, Martin Dolly from AT&T Labs, John 2172 Elwell from Siemens, Elliot Eichen and Robert Liao from Verizon, Dale 2173 Worley from Pingtel, Francois Audet from Nortel, Roni Even from 2174 Polycom, Jason Fischl from Counterpath, Josh Littlefield from Cisco, 2175 Nhut Nguyen from Samsung. 2177 The final revisions of this document were a product of design team 2178 discussions. The editor wishes to extend special appreciation to the 2179 following design team members for their numerous reviews and specific 2180 contributions to various sections: Josh Littlefield from Cisco 2181 (Overview, Section 6), Peter Blatherwick from Mitel (Section 6), 2182 Cullen Jennings (Security), Sam Ganesan (Section 6) and Mary Barnes 2183 (layout, Section 6). 2185 The following design team members are thanked for numerous reviews 2186 and general contributions: Martin Dolly from AT&T Labs, Jason Fischl 2187 from Counterpath, Alvin Jiang of Engin and Francois Audet from 2188 Nortel. 2190 The following SIPPING WG members are thanked for numerous reviews, 2191 comments and recommendations: John Elwell from Siemens, Donald Lukacs 2192 from Telcordia, Roni Even from Polycom, David Robbins from Verizon, 2193 Shida Schubert from NTT Advanced Technology Corporation, and Eugene 2194 Nechamkin from Broadcom. The editor would also like to extend a 2195 special thanks to the comments and recommendations provided by the 2196 SIPPING WG, specifically Keith Drage from Lucent (restructuring 2197 proposal). 2199 Additionally, appreciation is also due to Peter Koch for expert DNS 2200 advice. 2202 And finally, sincere appreciation is extended to the chairs (Mary 2203 Barnes from Nortel and Gonzalo Camarillo from Ericsson) and the Area 2204 Directors (Cullen Jennings from Cisco and Jon Peterson from Neustar) 2205 for facilitating discussions, reviews and contributions. 2207 11. References 2209 11.1. Normative References 2211 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 2212 Requirement Levels", BCP 14, RFC 2119, March 1997. 2214 [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an 2215 IANA Considerations Section in RFCs", BCP 26, RFC 2434, 2216 October 1998. 2218 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 2219 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 2220 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 2222 [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., 2223 Leach, P., Luotonen, A., and L. Stewart, "HTTP 2224 Authentication: Basic and Digest Access Authentication", 2225 RFC 2617, June 1999. 2227 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. 2229 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 2230 A., Peterson, J., Sparks, R., Handley, M., and E. 2231 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 2232 June 2002. 2234 [RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation 2235 Protocol (SIP): Locating SIP Servers", RFC 3263, 2236 June 2002. 2238 [RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific 2239 Event Notification", RFC 3265, June 2002. 2241 [RFC3319] Schulzrinne, H. and B. Volz, "Dynamic Host Configuration 2242 Protocol (DHCPv6) Options for Session Initiation Protocol 2243 (SIP) Servers", RFC 3319, July 2003. 2245 [RFC3361] Schulzrinne, H., "Dynamic Host Configuration Protocol 2246 (DHCP-for-IPv4) Option for Session Initiation Protocol 2247 (SIP) Servers", RFC 3361, August 2002. 2249 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 2250 Unique IDentifier (UUID) URN Namespace", RFC 4122, 2251 July 2005. 2253 [RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security 2254 (TLS) Protocol Version 1.1", RFC 4346, April 2006. 2256 [RFC4474] Peterson, J. and C. Jennings, "Enhancements for 2257 Authenticated Identity Management in the Session 2258 Initiation Protocol (SIP)", RFC 4474, August 2006. 2260 [RFC4483] Burger, E., "A Mechanism for Content Indirection in 2261 Session Initiation Protocol (SIP) Messages", RFC 4483, 2262 May 2006. 2264 [RFC4704] Volz, B., "The Dynamic Host Configuration Protocol for 2265 IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN) 2266 Option", RFC 4704, October 2006. 2268 11.2. Informative References 2270 [I-D.ietf-ecrit-phonebcp] 2271 Rosen, B. and J. Polk, "Best Current Practice for 2272 Communications Services in support of Emergency Calling", 2273 draft-ietf-ecrit-phonebcp-02 (work in progress), 2274 September 2007. 2276 [I-D.ietf-sip-outbound] 2277 Jennings, C. and R. Mahy, "Managing Client Initiated 2278 Connections in the Session Initiation Protocol (SIP)", 2279 draft-ietf-sip-outbound-10 (work in progress), July 2007. 2281 [RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol", 2282 STD 9, RFC 959, October 1985. 2284 [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor 2285 Extensions", RFC 2132, March 1997. 2287 [RFC4510] Zeilenga, K., "Lightweight Directory Access Protocol 2288 (LDAP): Technical Specification Road Map", RFC 4510, 2289 June 2006. 2291 [RFC4825] Rosenberg, J., "The Extensible Markup Language (XML) 2292 Configuration Access Protocol (XCAP)", RFC 4825, May 2007. 2294 Authors' Addresses 2296 Daniel Petrie 2297 SIPez LLC. 2298 34 Robbins Rd 2299 Arlington, MA 02476 2300 USA 2302 Email: dan.ietf AT SIPez DOT com 2303 URI: http://www.SIPez.com/ 2305 Sumanth Channabasappa (Editor) 2306 CableLabs 2307 858 Coal Creek Circle 2308 Louisville, Co 80027 2309 USA 2311 Email: sumanth@cablelabs.com 2312 URI: http://www.cablelabs.com/ 2314 Full Copyright Statement 2316 Copyright (C) The IETF Trust (2007). 2318 This document is subject to the rights, licenses and restrictions 2319 contained in BCP 78, and except as set forth therein, the authors 2320 retain all their rights. 2322 This document and the information contained herein are provided on an 2323 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 2324 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 2325 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 2326 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 2327 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 2328 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 2330 Intellectual Property 2332 The IETF takes no position regarding the validity or scope of any 2333 Intellectual Property Rights or other rights that might be claimed to 2334 pertain to the implementation or use of the technology described in 2335 this document or the extent to which any license under such rights 2336 might or might not be available; nor does it represent that it has 2337 made any independent effort to identify any such rights. Information 2338 on the procedures with respect to rights in RFC documents can be 2339 found in BCP 78 and BCP 79. 2341 Copies of IPR disclosures made to the IETF Secretariat and any 2342 assurances of licenses to be made available, or the result of an 2343 attempt made to obtain a general license or permission for the use of 2344 such proprietary rights by implementers or users of this 2345 specification can be obtained from the IETF on-line IPR repository at 2346 http://www.ietf.org/ipr. 2348 The IETF invites any interested party to bring to its attention any 2349 copyrights, patents or patent applications, or other proprietary 2350 rights that may cover technology that may be required to implement 2351 this standard. Please address the information to the IETF at 2352 ietf-ipr@ietf.org. 2354 Acknowledgment 2356 Funding for the RFC Editor function is provided by the IETF 2357 Administrative Support Activity (IASA).