--- 1/draft-ietf-sipping-config-framework-13.txt 2007-11-18 22:15:20.000000000 +0100 +++ 2/draft-ietf-sipping-config-framework-14.txt 2007-11-18 22:15:20.000000000 +0100 @@ -1,19 +1,19 @@ SIPPING D. Petrie Internet-Draft SIPez LLC. Intended status: Standards Track S. Channabasappa, Ed. -Expires: April 27, 2008 CableLabs - October 25, 2007 +Expires: May 21, 2008 CableLabs + November 18, 2007 A Framework for Session Initiation Protocol User Agent Profile Delivery - draft-ietf-sipping-config-framework-13 + draft-ietf-sipping-config-framework-14 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that @@ -24,21 +24,21 @@ and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on April 27, 2008. + This Internet-Draft will expire on May 21, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document specifies a framework to enable configuration of Session Initiation Protocol (SIP) User Agents in SIP deployments. The framework provides a means to deliver profile data that User @@ -59,65 +59,65 @@ 3.1. Reference Model . . . . . . . . . . . . . . . . . . . . . 6 3.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Profile Types . . . . . . . . . . . . . . . . . . . . . . 9 3.4. Profile delivery stages . . . . . . . . . . . . . . . . . 10 4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1. Simple Deployment Scenario . . . . . . . . . . . . . . . . 11 4.2. Devices supporting multiple users from different Service Providers . . . . . . . . . . . . . . . . . . . . 12 5. Profile Delivery Framework . . . . . . . . . . . . . . . . . . 14 5.1. Profile delivery stages . . . . . . . . . . . . . . . . . 14 - 5.1.1. Profile Enrollment . . . . . . . . . . . . . . . . . . 14 + 5.1.1. Profile Enrollment . . . . . . . . . . . . . . . . . . 15 5.1.2. Content Retrieval . . . . . . . . . . . . . . . . . . 17 5.1.3. Change Notification . . . . . . . . . . . . . . . . . 17 5.1.4. Enrollment Data and Caching . . . . . . . . . . . . . 18 5.2. Securing Profile Delivery . . . . . . . . . . . . . . . . 21 - 5.2.1. Securing Profile Enrollment . . . . . . . . . . . . . 21 + 5.2.1. Securing Profile Enrollment . . . . . . . . . . . . . 22 5.2.2. Securing Content Retrieval . . . . . . . . . . . . . . 23 - 5.2.3. Securing Change Notification . . . . . . . . . . . . . 24 + 5.2.3. Securing Change Notification . . . . . . . . . . . . . 23 5.3. Additional Considerations . . . . . . . . . . . . . . . . 24 5.3.1. Identities and Credentials . . . . . . . . . . . . . . 24 - 5.3.2. Profile Enrollment Request Attempt . . . . . . . . . . 26 - 5.3.3. Device Types . . . . . . . . . . . . . . . . . . . . . 30 - 5.3.4. Profile Data . . . . . . . . . . . . . . . . . . . . . 30 - 5.3.5. Profile Data Frameworks . . . . . . . . . . . . . . . 31 + 5.3.2. Profile Enrollment Request Attempt . . . . . . . . . . 25 + 5.3.3. Device Types . . . . . . . . . . . . . . . . . . . . . 29 + 5.3.4. Profile Data . . . . . . . . . . . . . . . . . . . . . 29 + 5.3.5. Profile Data Frameworks . . . . . . . . . . . . . . . 30 5.3.6. Additional Profile Types . . . . . . . . . . . . . . . 31 - 5.3.7. Deployment considerations . . . . . . . . . . . . . . 32 - 5.4. Usage of Outbound . . . . . . . . . . . . . . . . . . . . 32 - 6. Event Package Definition . . . . . . . . . . . . . . . . . . . 33 - 6.1. Event Package Name . . . . . . . . . . . . . . . . . . . . 33 - 6.2. Event Package Parameters . . . . . . . . . . . . . . . . . 33 - 6.3. SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 36 - 6.4. Subscription Duration . . . . . . . . . . . . . . . . . . 36 - 6.5. NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . 37 - 6.6. Notifier Processing of SUBSCRIBE Requests . . . . . . . . 37 - 6.7. Notifier Generation of NOTIFY Requests . . . . . . . . . . 37 - 6.8. Subscriber Processing of NOTIFY Requests . . . . . . . . . 38 - 6.9. Handling of Forked Requests . . . . . . . . . . . . . . . 38 - 6.10. Rate of Notifications . . . . . . . . . . . . . . . . . . 39 - 6.11. State Agents . . . . . . . . . . . . . . . . . . . . . . . 39 - 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 - 7.1. Example 1: Device requesting profile . . . . . . . . . . . 39 - 7.2. Example 2: Device obtaining change notification . . . . . 42 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46 - 8.1. SIP Event Package . . . . . . . . . . . . . . . . . . . . 46 - 8.2. Registry of SIP configuration profile types . . . . . . . 46 - 9. Security Considerations . . . . . . . . . . . . . . . . . . . 47 - 9.1. Local-network profile . . . . . . . . . . . . . . . . . . 49 - 9.2. Device profile . . . . . . . . . . . . . . . . . . . . . . 50 - 9.3. User profile . . . . . . . . . . . . . . . . . . . . . . . 51 - 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 52 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 53 - 11.1. Normative References . . . . . . . . . . . . . . . . . . . 53 - 11.2. Informative References . . . . . . . . . . . . . . . . . . 54 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 54 - Intellectual Property and Copyright Statements . . . . . . . . . . 56 + 5.3.7. Deployment considerations . . . . . . . . . . . . . . 31 + 5.4. Support for NATs . . . . . . . . . . . . . . . . . . . . . 31 + 6. Event Package Definition . . . . . . . . . . . . . . . . . . . 32 + 6.1. Event Package Name . . . . . . . . . . . . . . . . . . . . 32 + 6.2. Event Package Parameters . . . . . . . . . . . . . . . . . 32 + 6.3. SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 35 + 6.4. Subscription Duration . . . . . . . . . . . . . . . . . . 35 + 6.5. NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . 36 + 6.6. Notifier Processing of SUBSCRIBE Requests . . . . . . . . 36 + 6.7. Notifier Generation of NOTIFY Requests . . . . . . . . . . 36 + 6.8. Subscriber Processing of NOTIFY Requests . . . . . . . . . 37 + 6.9. Handling of Forked Requests . . . . . . . . . . . . . . . 37 + 6.10. Rate of Notifications . . . . . . . . . . . . . . . . . . 38 + 6.11. State Agents . . . . . . . . . . . . . . . . . . . . . . . 38 + 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 + 7.1. Example 1: Device requesting profile . . . . . . . . . . . 38 + 7.2. Example 2: Device obtaining change notification . . . . . 41 + 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45 + 8.1. SIP Event Package . . . . . . . . . . . . . . . . . . . . 45 + 8.2. Registry of SIP configuration profile types . . . . . . . 45 + 9. Security Considerations . . . . . . . . . . . . . . . . . . . 46 + 9.1. Local-network profile . . . . . . . . . . . . . . . . . . 47 + 9.2. Device profile . . . . . . . . . . . . . . . . . . . . . . 48 + 9.3. User profile . . . . . . . . . . . . . . . . . . . . . . . 50 + 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 50 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 51 + 11.1. Normative References . . . . . . . . . . . . . . . . . . . 51 + 11.2. Informative References . . . . . . . . . . . . . . . . . . 52 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 52 + Intellectual Property and Copyright Statements . . . . . . . . . . 54 1. Introduction SIP User Agents require configuration data to function properly. Examples include local network, device and user specific information. A configuration data set specific to an entity is termed a profile. For example, device profile contains the configuration data related to a device. The process of providing devices with one or more profiles is termed profile delivery. Ideally, this profile delivery process should be automatic and require minimal or no user @@ -348,44 +348,46 @@ variation in between, one needs to allow for profile delivery via one, or more, Providers. The framework accomplishes this by specifying multiple profile types and a set of profile delivery stages to obtain them. These are introduced in the sub-sections to follow. 3.3. Profile Types The framework handles the presence of potentially different Providers by allowing for multiple profile types. Clients request each profile - and obtain them from the same, or different, Providers. Additional - profile types may also be specified. A deployment can also choose to - pre-configure the device to request only a subset of the specified - profile types. The framework specifies three basic profile types, as - follows: + separately, and obtain them from the same, or different, Providers. + A deployment can also choose to pre-configure the device to request + only a subset of the specified profile types. The framework + specifies three basic profile types, as follows: Local Network Profile: contains configuration data related to the local network to which a device is directly connected, provided by the Local Network Provider. Device Profile: contains configuration data related to a specific device, provided by the Device Provider. User Profile: contains configuration data related to a specific User, as required to reflect that user's preferences and the particular services subscribed to. It is provided by the SIP Service Provider. - PDSs and devices will implement all the three profile types. Unless - configured otherwise, a device will try to obtain all the three - profile types. A retrieval order is specified by the framework. The - data models associated with each profile type is out of scope for - this document. Follow-on standardization activities are expected to - specify such data models. + Additional profile types may also be specified. + PDSs and devices will implement all the three profile types. A + device that has not been configured otherwise will try to obtain all + the three profile types, in the order specified by this framework. + The device can be configuration with a different behavior via profile + data previously obtained by the device, other means such as pre- + configuration or manual configuration. The data models associated + with each profile type are out of scope for this document. Follow-on + standardization activities are expected to specify such data models. 3.4. Profile delivery stages The framework specified in this document requires a device to explicitly request profiles. It also requires one or more PDSs which provide the profile data. The processes that lead a device to obtain profile data, and any subsequent changes, can be explained in three stages, termed the profile delivery stages. Profile Enrollment: the process by which a device requests, and if @@ -410,39 +412,37 @@ representative use cases to further illustrate how this Framework can be utilized in SIP deployments. The first use case is simplistic in nature, whereas the second is relatively complex. The use cases illustrate the effectiveness of the framework in either scenario. For Security Considerations please refer to Section 5 and Section 9. 4.1. Simple Deployment Scenario Description: Consider a deployment scenario (e.g., a small private - enterprise) where a single entity enables the local network, manages - deployed devices and provides SIP services. The devices only attach - to the local network, and are pre-configured with a single user. - - The following assumptions apply: - o The device profile data contains all the information necessary - for the device to participate in the local network and obtain - services. - o The device is pre-configured to only request the device profile. - o The enrollment notification contains the profile data (profile - content retrieval is not required). - o There are no proxies in the network. + enterprise) where a participating device implements this framework + and is configured, using previously obtained profile data, to request + only the device profile. Assume that the device operates in the same + network as the PDS (i.e., there is no NAT) and it obtains its IP + configuration using DHCP. Typical communication between the device + and the PDS will traverse one or more SIP proxies, but is not + required, and is omitted in this illustration. - Figure 4 illustrates this use case and highlights the communications - relevant to the framework specified in this document. + Figure 4 illustrates the sequence of events that include device + startup and a successful profile enrollment for the device profile + that results in device profile data. It then illustrates how a + change in the profile data is delivered via Profile Change + Notification. +----------------------+ - +--------+ | Local Network, Device| - | Device | |& SIP Service Provider| + +--------+ | Provider's Network | + | Device | | | | | | | +--------+ | DHCP PDS | +----------------------+ | | | (A) |<============== DHCP =============>| | | | | | | | (B) |<=========== Profile Enrollment ============>| | | Profile data @@ -445,46 +445,48 @@ | | | | (B) |<=========== Profile Enrollment ============>| | | Profile data | | is modified | | (C) |<============ Profile Change ================| | Notification | | | | | + Figure 4: Use Case 1 The following is an explanation of the interactions in Figure 4. + (A) Upon initialization, the device obtains IP configuration - parameters using DHCP. - (B) The device performs Profile Enrollment for the device profile; - the device profile data is contained in the enrollment - notification. - (C) Due to a modification of the device profile, a Profile Change - Notification is sent across to the device, along with the + parameters such as IP address using DHCP. + (B) The device requests profile enrollment for the device profile. + Successful enrollment provides it with a notification containing + the device profile data. + (C) Due to a modification of the device profile, a profile change + notification is sent across to the device, along with the modified profile. 4.2. Devices supporting multiple users from different Service Providers - Description: Consider a single device (e.g., Kiosk at an airport) - that allows multiple users to obtain services from a list of pre- - configured SIP Service Providers. + Description: Consider a single device that allows multiple users to + obtain services from different SIP Service Providers, e.g., a kiosk + at an airport. The following assumptions apply: o Provider A is the Device and Local Network Provider for the device, and the SIP Service Provider for user A; Provider B is the SIP Service Provider for user B. o Profile enrollment always results in content indirection information requiring profile content retrieval. - o Communication between the device and the PDSs is facilitated by - SIP proxies. + o Communication between the device and the PDSs is facilitated via + one or more SIP proxies (only one is shown in the illustration). Figure 4 illustrates the use case and highlights the communications relevant to the framework specified in this document. User User A B +----------------------+ +----------------------+ +--------+ | Provider | | Provider | | Device | | A | | B | | | | | | | +--------+ | DHCP PROXY PDS | | PROXY PDS | @@ -545,32 +547,37 @@ attempts communication via the user Interface. The device uses the user supplied information (including any credential information) and requests profile enrollment for user A's profile. Successful enrollment and profile content retrieval results in services for user A. (E) At a different point in time, user B with a service relationship with Provider B attempts communication via the user Interface. It enrolls and retrieves user B's profile and this results in services for user B. + The discovery mechanisms for profile enrollment described by the + framework, or the profile data themselves, can result in outbound + proxies that support devices behind NATs, using procedures specified + in [I-D.ietf-sip-outbound]. + 5. Profile Delivery Framework This section specifies the profile delivery framework. It provides the requirements for the three profile delivery stages introduced in Section 3.4 and presents the associated security requirements. It also presents considerations such as back-off and retry mechanisms. 5.1. Profile delivery stages The three profile delivery stages - enrollment, content retrieval and - change notification - apply to any profile type specified for use - with this framework. The following sub-sections provide the + change notification - apply separately to each profile type specified + for use with this framework. The following sub-sections provide the requirements associated with each stage. 5.1.1. Profile Enrollment Profile enrollment is the process by means of which a device requests, and receives, profile data. Each profile type specified in this document requires an independent enrollment request. However, a particular PDS can support enrollment for one or more profile types. Profile enrollment consists of the following operations, in the @@ -582,21 +589,21 @@ SUBSCRIBE request [RFC3265] for the 'ua-profile' event package, specified in Section 6. The profile being requested is indicated using the 'profile-type' parameter. The device MUST transmit the SIP SUBSCRIBE message via configured outbound proxies for the destination domain, or in accordance with RFC 3263 [RFC3263]. The device needs certain data to create an enrollment request, form a Request URI, and authenticate to the network. This includes the profile provider's domain name, identities and credentials. Such data can be "configured" during device - manufacturing, by the user, or via profile data retrieval (see + manufacturing, by the user, or via profile data enrollment (see Section 5.3.1). The data can also be "discovered" using the procedures specified by this framework. The "discovered" data can be retained across device resets (but not across factory resets) and such data is referred to as "cached". Thus, data can be configured, discovered or cached. The following requirements apply. * If the device is configured with a specific domain name (for the local network provider or device provider), it MUST NOT attempt "discovery" of the domain name. This is the case when @@ -771,39 +778,41 @@ SIP UA instance. Even though every device may get the same (or similar) local-network Profile, the uniqueness of the "+sip.instance" parameter provides an important capability. Having unique instance ID fields allows the management of the local network to track devices present in the network and consequently also manage resources such as bandwidth allocation. 5.1.4.2. Device Profile Type Once associated with a device, the device provider is not expected to - change frequently. An exception is a user who changes device - providers, but retains the device. Thus, the device is allowed to, - and SHOULD cache the Subscription URI for the device profile upon - successful enrollment. Exceptions include cases where the device - identifier has changed (e.g., new network card), device provider - information has changed (e.g., user initiated change) or the device - cannot obtain its profile using the Subscription URI. Thus, when - available, the device MUST use a cached Subscription URI. If no - cached URI is available then it needs to create a Subscription URI. - To create a Subscription URI, the device needs a device identity and - the device provider's domain name. Unless already configured, the - device needs to discover the necessary information and form the - subscription URI. In such cases, the following requirements apply - for creating a Subscription URI for requesting the device profile: + change frequently. Thus, the device is allowed to, and SHOULD cache + the Subscription URI for the device profile upon successful + enrollment. Exceptions include cases where the device identifier has + changed (e.g., new network card), device provider information has + changed (e.g., user initiated change) or the device cannot obtain its + profile using the Subscription URI. Thus, when available, the device + MUST use a cached Subscription URI. If no cached URI is available + then it needs to create a Subscription URI. To create a Subscription + URI, the device needs a device identity and the device provider's + domain name. Unless already configured, the device needs to discover + the necessary information and form the subscription URI. In such + cases, the following requirements apply for creating a Subscription + URI for requesting the device profile: - o The device MUST use the device identifier and the device - provider's domain name to form the Request URI. + o The device MUST populate the user part of the Request URI with the + device identifier. The device MUST set the host portion of the + Request URI to the domain name of the device provider. The device + identifier format is explained in detail later in this section. o The device MUST set the "From" field to a value of anonymous@ . + o The device MUST include the +sip.instance parameter within the 'Contact' header, as specified in [I-D.ietf-sip-outbound]. The device MUST use the same value as the one presented while requesting the local-network profile. Note that the discovered AoR for the Request URI can be overridden by a special, provisioned, AoR that is unique to the device. In such cases, the provisioned AoR is used to form the Request URI and to populate the From field. @@ -800,58 +809,58 @@ o The device MUST include the +sip.instance parameter within the 'Contact' header, as specified in [I-D.ietf-sip-outbound]. The device MUST use the same value as the one presented while requesting the local-network profile. Note that the discovered AoR for the Request URI can be overridden by a special, provisioned, AoR that is unique to the device. In such cases, the provisioned AoR is used to form the Request URI and to populate the From field. - If the device is not configured with an AoR, and needs a domain name, - it can either use a configured domain name, if available, or discover - it. The options to discover are described below. The device MUST - use the results of each successful discovery process for one - enrollment attempt, in the order specified below. + If the device is not configured with an AoR, and needs a domain name + to populate the Request URI and the From field, it can either use a + configured domain name, if available, or discover it. The options to + discover are described below. The device MUST use the results of + each successful discovery process for one enrollment attempt, in the + order specified below. o Option 1: Devices that support DHCP MUST attempt to obtain the - hostname of the outbound proxy during the DHCP process, using the - DHCP option for SIP servers defined in [RFC3361] or [RFC3319] (for - IPv4 and IPv6 respectively). + domain name of the outbound proxy during the DHCP process, using + the DHCP option for SIP servers defined in [RFC3361] or [RFC3319] + (for IPv4 and IPv6 respectively). o Option 2: Devices that support DHCP MUST attempt to obtain the local IP network domain during the DHCP process (refer to [RFC2132] and [RFC4704] ). o Option 3: Devices MUST use the local network domain name (configured or discovered to retrieve the local-network profile), prefixing it with the label "_sipuaconfig". If the device needs to create a subscription URI and needs to use its device identifier, it MUST use the UUID-based URN representation as specified in [RFC4122]. The following requirements apply: o When the device has a non-alterable MAC address it SHOULD use version 1 UUID representation with the timestamp and clock sequence bits set to a value of '0'. This will allow for easy recognition, and uniqueness of MAC address based UUIDs. An exception is the case where the device supports independent device configuration for more than one SIP UA. An example would be multiple SIP UAs on the same platform. - o If the device cannot use a non-alterable MAC Address, it SHOULD - use an alternative non-alterable device identifier. For example, - the International Manufacturer's Equipment Identifier (IMEI) for - mobile devices. + o If the device cannot use a non-alterable device identifier, it + SHOULD use an alternative non-alterable device identifier. For + example, the International Manufacturer's Equipment Identifier + (IMEI) for mobile devices. o If the device cannot use a non-alterable MAC Address, it MUST be use the same approach as defining a user agent Instance ID in [I-D.ietf-sip-outbound]. - o As a note, when the URN is used as the user part of the Request - URI, it MUST be URL escaped - The colon (":") is not a legal character in the user part of an - addr-spec ([RFC4122]), and must be escaped. + o Note: when the URN is used as the user part of the Request URI, it + MUST be URL escaped since the colon (":") is not a legal character + in the user part of an addr-spec ([RFC4122]), and must be escaped. For example, the instance ID: urn:uuid:f81d4fae-7ced-11d0-a765-00a0c91e6bf6@example.com would be escaped to look as follows in a URI: sip:urn%3auuid%3af81d4fae-7ced-11d0-a765-00a0c91e6bf6@ example.com The ABNF for the UUID representation is provided in [RFC4122] @@ -859,235 +868,217 @@ 5.1.4.3. User Profile Type To create a Subscription URI to request the user profile on behalf of a user, the device needs to know the user's AoR. This can be statically or dynamically configured on the device (e.g., user input, or propagated as part of the device profile). Similar to device profiles, the content and propagation of user profiles may differ, based on deployment scenarios (i.e., users belonging to the same domain may - or may not - be provided the same profile). To create a subscription URI, the following rules apply: + o The device MUST set the Request URI to the user AoR. o The device MUST populate the "From" field with the user AoR. + An authoritative SIP proxy for a SIP provider's network that receives + a profile enrollment request for the user profile type will route + based on the Event Header field values, thus allowing a subscription + to the user's AoR to be routed to the appropriate PDS. + 5.2. Securing Profile Delivery Profile data can contain sensitive information that needs to be secured, such as identities and credentials. Security involves authentication, message integrity and privacy. Authentication is the process by which you verify that an entity is who it claims to be, such as a user AoR presented during profile enrollment. Message integrity provides the assurance that the message contents transmitted between two entities, such as between the PDS and the device, has not been modified during transit. Privacy ensures that the message contents have not been subjected to monitoring by - unwanted elements, during transit. At a minimum, authentication and - message integrity are required to ensure that the profile contents - were received by a valid entity, from a valid source, and without any - modifications during transit. For profiles that contain sensitive - data, privacy is required to ensure that the data is not snooped by - unwanted elements. + unwanted elements during transit. For profile data that contains + sensitive information, authentication and message integrity are + required to ensure that the profile contents were received by a valid + entity, from a valid source, and without any modifications during + transit. For profiles that contain sensitive data, privacy is also + required. - For an overview of potential security threats, refer to Section 9.The - requirements to address the concerns are required for all stages of - profile delivery, and are presented in the following subsections. + For an overview of potential security threats, refer to Section 9. + For information on how the device can be configured with identities + and credentials, refer to Section 5.3.1. The following subsections + provide the security requirements associated with each profile + delivery stage, and applies to each of profile types specified by + this framework. 5.2.1. Securing Profile Enrollment - During profile enrollment, the device needs to authenticate two - entities. The next-hop entity, i.e., a proxy or a PDS, to which the - device transmits the profile enrollment request, and the initial - notification from the PDS. On the Provider's side, a PDS that - recognizes an identity, such as the user AoR, that will result in - sensitive (or even non-generic) data included in the initial or - change notifications, will need to authenticate the device claiming - such identities. - - Authentication of the next-hop entity by the device is accomplished - by using the procedures specified in [RFC2818], Section 3.1, over an - establish TLS connection ([RFC4346]). The 'Server Identity' in this - case is always the domain of the next-hop SIP entity. A device - presenting a SIPS URI as a user AoR MUST establish TLS with the next- - hop SIP entity to which it sends the enrollment request. In all - other cases, the device SHOULD still attempt establishment of TLS - with the next-hop SIP entity. An exception is when it is explicitly - configured not to. If it attempts to establish TLS and it fails - because the next-hop SIP entity does not support TLS, the device - SHOULD attempt other resolved next-hop SIP entities prior to - attempting enrollment without TLS. If the device attempts to - establish a TLS session and fails to verify the next-hop entity - (e.g., the domain name could not be verified) the device MUST NOT - continue with the current enrollment request, and must retry with - other resolved next-hop SIP entities. If the device is attempting to - establish TLS, and exhausts the entire list of next-hop entities, - then: - - o if the device has a user interface, and unless configured not to, - the device SHOULD prompt the user if it can continue without TLS; - o if the device has no user interface, and unless configured not to, - the device MUST retry enrollment without TLS and without - presenting any configured user AoR (note: this means that user - profiles cannot be retrieved). - - In the absence of a Server Identity authenticated TLS session with - the next-hop SIP entity: - o the device MUST NOT respond to any authentication challenges; - o the device MUST ignore any notifications containing sensitive - profile data. + Profile enrollment may result in sensitive profile data. In such + cases, the PDS MUST authenticate the device, except during the + bootstrapping scenario when the device does not have existing + credentials. Additionally, the device MUST authenticate the PDS to + ensure that it is obtaining sensitive profile data from a valid PDS, + except in the bootstrapping scenario. - Once enrolled, the device obtains the initial notification. This is - authenticated using two methods. If this initial notification was - transmitted on the mutually authenticated TLS session established for - enrollment requests, then it is considered authenticated. If not, - the device MUST verify the presence of a SIP Identity header from the - PDS and validate that it belongs to the Provider's domain. If the - SIP Identity header is absent or the device cannot validate it, the - device MUST reject any sensitive profile data. If the SIP Identity - header is present, and the device cannot validate it, then it MUST - reject the profile data and retry enrollment. To allow for this - authentication, the PDS SHOULD include the SIP Identity header as - specified in [RFC4474]. Exceptions are PDSs that do not serve - sensitive profiles, or those in deployments where communication with - the PDS in the absence of a mutually authenticated TLS is disallowed. - When the SIP Identify header is used, the PDS MUST set the host - portion of the AoR in the 'From' header to the Provider's domain. + To authenticate a device that has been configured with identities and + credentials as specified in Section 5.3.1 and support profiles + containing sensitive profile data (refer to Section 5.3.4), devices + and PDSs MUST support Digest Authentication as specified in + [RFC3261]. Future enhancements may provide other authentication + methods such as authentication using X.509 certificates. For the + device to authenticate the PDS, the device MUST mutually authenticate + with the PDS during digest authentication (device challenges the + client that responds with the Authorization header). Transmission of + sensitive profile data also requires message integrity. This can be + provided by configuring the device with a SIPS URI resulting in TLS + establishment ([RFC4346]). TLS also prevents offline dictionary + attacks when digest authentication is used. Thus, in the absence of + TLS, the device MUST NOT respond to any authentication challenges. + It is to be noted that the digest credentials used for obtaining + profile data via this framework may, or may not, be the same as that + used for SIP registration (see Section 5.3.1). - Note that both Server Identity authentication ([RFC2818]) and SIP - Identity ([RFC4474] require X.509 certificates. Additionally, the - use of TLS and mutual authentication also provides message integrity - and privacy between the device and the next-hop entity. When the - next-hop entity is a proxy, the Provider will need ensure mutual - authentication and integrity between intermediary components such as - proxies and PDSs. This is mandatory when a SIPS URI is presented by - the device. + When the PDS challenges a profile enrollment request, and it fails, + the PDS MAY refuse enrollment or provide profile data without the + user-specific information (e.g., to bootstrap a device that may have + misplaced credentials). If the device challenges, but fails to + authenticate the PDS, it MUST reject the initial notification and + retry the profile enrollment process. If the device is configured + with a SIPS URI and TLS establishment fails because the next-hop SIP + entity does not support TLS, the device SHOULD attempt other resolved + next-hop SIP entities. When the device establishes TLS with the + next-hop entity, the device MUST use the procedures specified in + [RFC2818], Section 3.1, for authentication, unless it does not have + any configured information to verify the same (e.g., prior to + bootstrapping). The 'Server Identity' in this case is always the + domain of the next-hop SIP entity. If the device attempts + validation, and it fails, it MUST reject the intial notification and + retry profile enrollment. In the absence of TLS and a mechanism for + mutual authentication, the PDS MUST NOT present any sensitive profile + data in the initial notification, except when the device is being + boostrapped. It MAY still use content indirection to transmit + sensitive profile data. - Authentication of the identity requesting the profile is accomplished - by the PDS by using the Digest Authentication mechanism, over TLS. - Thus, devices and PDSs MUST implement Digest Authentication specified - in [RFC3261], and TLS as specified in [RFC4346]. If the device - presents a user AoR, it should be recognized by the network. If not - (e.g., discovered or device identities) it may not be known by the - PDS (and hence, may not be associated with credentials). If known by - the PDS and the notification will result in data specific to the user - AoR, the PDS MUST challenge the request using Digest authentication - specified in [RFC3261]. If the device successfully responds to the - challenge, it is provided the initial notification, which contains - the profile data within, or via content indirection. If user - authentication fails the PDS MAY refuse enrollment, or provide - profile data without the user-specific information. As a note, if - the PDS attempts authentication in the absence of an authenticated - TLS session between the device and the next-hop entity, it will be - ignored by the device. A PDS that does not perform authentication - MUST use content indirection to a PCC that supports authentication, - integrity protection and privacy for conveying sensitive profile - data. + When a device is being provided with bootstrapping profile data + containing sensitive information, the PDS SHOULD use the SIP Identity + header as specified in [RFC4474] within the notification. This helps + with devices that MAY be pre-configured with certificates to validate + bootstrapping sources (e.g., list of allowed domain certificates, or + a list of root CA certificates using PKI). Further, the profile data + may contain the domain certificate used for creating the SIP Identity + header, for devices that are not pre-configured with any information, + and can be used to guarantee header and body integrity. It can also + allow the device to present the identity of the PDS to a user for + verification (if such an interface exists). When the SIP Identity + header is used, the PDS MUST set the host portion of the AoR in the + 'From' header to the Provider's domain (the user portion is a entity- + specific identifier). If the device is capable of validating the SIP + Identity, and it fails, it MUST reject bootstrapping profile data. 5.2.2. Securing Content Retrieval Initial or change notifications following a successful enrollment can provide a device with the requested profile data, or use content indirection to direct it to a PCC that can provide the profile data. This document specifies HTTP and HTTPS as content retrieval protocols. If the profile is provided via content indirection and contains sensitive profile data then the PDS MUST use a HTTPS URI for content indirection. PCCs and devices MUST NOT use HTTP for sensitive - profile data. A device MUST authenticate the PCC as specified in + profile data, except for bootstrapping a device via the device + profile. A device MUST authenticate the PCC as specified in [RFC2818], Section 3.1. A device that is being provided with profile - data that contains sensitive data MUST be authenticated using Digest - as specified in [RFC2617], with the exception of a device that is - being bootstrapped for the first time. The resulting mutually - authenticated TLS channel also provides message integrity. + data that contains sensitive data MUST be authenticated using digest + authentication as specified in [RFC2617], with the exception of a + device that is being bootstrapped for the first time via the device + profile. The resulting TLS channel also provides message integrity + and privacy. 5.2.3. Securing Change Notification - A successful profile enrollment results in an initial notification. If the device requested enrollment via a SIP subscription with a non- zero 'Expires' parameter, it can also result in change notifications - for the duration of the subscription. - - If the device established TLS with the next-hop entity then any such - notifications SHOULD be sent over the same TLS session by the PDS. - If the TLS session exists, the device MUST ignore any notifications - sent outside the TLS session. If no such TLS session exists, the - device MUST NOT accept any sensitive profile data without verifying - the presence of, and validating, a SIP Identity header. - - A PDS that does not support TLS MUST use content indirection to a PCC - that supports authentication and integrity protection for conveying - sensitive profile data. + for the duration of the subscription. For change notifications + containing sensitive profile data, this framework RECOMMENDS the use + of the SIP Identity header as specified in [RFC4474]. When the SIP + Identity header is used, the PDS MUST set the host portion of the AoR + in the 'From' header to the Provider's domain (the user portion is a + entity-specific identifier). This provides header and body integrity + as well. However, for sensitive profile data that needs privacy and + is not being transmitted over a channel such as TLS, the PDS MUST use + content indirection. Additionally, the PDS MUST also use content + indirection for notifications containing sensitive profile data, when + the profile enrollment was not authenticated. 5.3. Additional Considerations This section provides additional considerations such as details on how a device obtains identities and credentials, backoff and retry methods, guidelines on profile data and additional profile types. 5.3.1. Identities and Credentials When requesting a profile the device can provide an identity such as a user AoR. To do so, the device needs to be configured. This can - be accomplished in one of many ways: + be accomplished in one of the following ways: Pre-configuration The device may be pre-configured with identities and associated credentials, such as a user AoR and digest password. Out-of-band methods A device or Provider may provide hardware- or software-based credentials such as SIM cards or USB drives. End-user interface - The end-user may be provided with user AoRs and credentials. The - end-user can then configure the device (using a user interface), - or present when required (e.g., IM login screen). + The end-user may be provided with the necessary identities and + credentials. The end-user can then configure the device (using a + user interface), or present when required (e.g., IM login screen). Using this framework When a device is initialized, even if it has no pre-configured information, it can request the local-network and device profiles. - In such a case the device profile can provide three kinds of - information: - * Profile data that allows the end-user to communicate with the - device or SIP service provider. The provider can then use any - applicable method (e.g., web portal) to provide the user AoR. - * Profile data that redirects the device to an entity, such as - the PCC, that can provide identity data. As an example, - consider a device that has a X.509 certificate that can be - authenticated by the PCC. In such a case, the PCC can use - HTTPS to provide the user AoR. - * Profile data containing user identity to be used. This can be - used in cases where the device is initialized for the first - time, or after a factory reset, in the device provider's - network. + In such a case the device profile can provide one of the following + to bootstap the device: - If a device presents a user AoR in the enrollment request, the PDS - can challenge it. To respond to such authentication challenges, the - device needs to have associated credentials. Thus, any of the - configuration methods indicated above need to provide the user - credentials along with any AoRs. + * Profile data that allows the end-user to communicate by non-SIP + means with the device provider or SIP service provider. The + provider can then use any applicable method (e.g., web portal) + to provide the user AoR. + * Content indirection information to a PCC that can provide + identities and credentials. As an example, consider a device + that has a X.509 certificate that can be authenticated by the + PCC. In such a case, the PCC can use HTTPS to provide + identities and associated credentials. + * Profile data containing identities and credentials that can be + used to bootstrap the device. This can be used in cases where + the device is initialized for the first time, or after a + factory reset. This can be considered only in cases where the + device is initialized in the Provider's network, for obvious + security reasons. Additionally, AoRs are typically known by PDSs that serve the domain indicated by the AoR. Thus, devices can only present the configured AoRs in the respective domains. An exception is the use of federated identities. This allows a device to use a user's AoR in multiple - domains. - - The configured user AoR and associated credentials can be used in - applicable domains for any of the profile types specified by this - framework. In the absence of the user AoR, the device is not - expected to contain any other credentials. Future enhancements can - specify additional identities and credentials. + domains. Further even within the same domain, the device's domain + proxy and the PDS may be in two different realms, and as such may be + associated with different credentials for digest authentication. In + such cases, multiple credentials may be configured, and associated + with the realms in which they are to be used. This framework + specifies only digest authentication and the device is not expected + to contain any other credentials. Future enhancements can specify + additional identities and credentials such as X.509 certificates. 5.3.2. Profile Enrollment Request Attempt A state diagram representing a device requesting any specific profile defined by this framework is shown in Figure 6. +------------+ | Initialize | +-----+------+ | @@ -1129,96 +1120,103 @@ ,->| Profile +--/Apply Profile-->| Successful | / | | |(monitoring)|<--. Timeout +--+---------+ +--+----+----+ : /Retry ; ^ | : ; `------' | NOTIFY w. Cont.Ind | `-------' +---/Retrieve Profile-----+ NOTIFY w. Profile /Apply Profile Figure 6: Device State Diagram As a reminder: - o The timeout for SIP messages is specified by [RFC3261] + o The timeout for SIP messages is specified by [RFC3261]. In the + cases where this is not specified such as the timeout to wait for + the initial notification during profile enrollment, it is left to + device implementations or future protocol enhancements. o The timeout for profile retrieval using content indirection will - be as specified by profile retrieval protocols employed + be as specified by profile retrieval protocols employed. If none + exists, it is left to device implementations. In addition, since profile enrollment is a process unique to this framework, the device MUST follow the enrollment attempt along with exponential backoff and retry mechanisms as indicated in Figure 7. Function for Profile Enrollment () - Iteration i=0 + Init Function: Iteration i=0 - Loop: Attempt + Loop 1: Attempt - Loop: For each SIP Subscription URI + Loop 2: For each SIP Subscription URI - Loop: For each next-hop SIP entity + Loop 3: For each next-hop SIP entity - Prepare & transmit Enrollment Request - Await Enrollment Acceptance and initial NOTIFY + If the profile enrollment is successful = Exit this function() + If profile enrollment fails due to an explicit failure or a timeout as specified in RFC3261 - = Continue with this function() + = Continue with the next-hop SIP entity (Loop 3) - End Loop: Next-hop SIP entity contact + End Loop: Loop 3 - End Loop: SIP Subscription URI formation + End Loop: Loop 2 (Note: If you are here, profile enrollment did not succeed) + Is any valid cached profile data available? - = If yes, use it and continue with this function() + = If yes, use it and continue with Loop 1 + If the enrollment request is for a non-mandatory profile - = then spawn the next profile and continue with this - function() + = Start profile enrollment for the next profile, + if applicable - Delay for 2^i*(64*T1); -- this is exponential backoff - increment i; - If i>8, reset i=8; - End loop: Attempt + End loop: Loop 1 End Function() Figure 7: Profile Enrollment Attempt (pseudo-code) The pseudo-code above (Figure 7) allows for cached profiles to be used. However, any cached Local Network profile MUST NOT be used unless the device can ensure that it is in the same local network which provided the cached data. This framework does not provide any procedures for local network recognition. Any cached device and user profiles MUST only be used in domains that they are associated with. For example, a cached device profile is used only when the associated domain matches the current device provider's domain. If a PDS wants to invalidate a profile it may do so by transmitting a NOTIFY with an - 'empty profile' (not to be confused with an empty NOTIFY). A device - receiving such a NOTIFY MUST discard the applicable profile (i.e., it - cannot even store it in the cache). Additionally, if a factory reset - is available and performed on a device, it MUST reset the device to - its initial state prior to any configuration. Specifically, the - device MUST set the device back to the state when it was originally - distributed. + 'empty profile', i.e., profile instance without any included data (if + supported by the profile data model; not to be confused with an empty + NOTIFY), or via an explicit profile data element that invalidates the + data. A device receiving such a NOTIFY MUST discard the applicable + profile (i.e., it cannot even store it in the cache). Additionally, + if a factory reset is available and performed on a device, it MUST + reset the device to its initial state prior to any configuration. + Specifically, the device MUST set the device back to the state when + it was originally distributed. The order of profile enrollment is important. For the profiles - specified in this framework, the device must enroll in the order: - local-network, device and user. The pseudo-code presented earlier - (Figure 7) differentiates between 'mandatory' and 'non-mandatory' - profiles. This distinction is left to profile data definitions. + specified in this framework, the device must enroll in the following + default order: local-network, device and user. The pseudo-code + presented earlier (Figure 7) differentiates between 'mandatory' and + 'non-mandatory' profiles. This distinction is left to profile data + definitions. It is to be noted that this framework does not allow the devices to inform the PDSs of profile retrieval errors such as invalid data. Follow-on standardization activities are expected to address this feature. 5.3.3. Device Types The examples in this framework tend to associate devices with entities that are accessible to end-users. However, this is not @@ -1314,21 +1312,21 @@ o The relationship between devices and users can be many-to-many (e.g., a particular device may allow for many users to obtain subscription services through it, and individual users may have access to multiple devices). o Each user may have different preferences for use of services, and presentation of those services in the device user interface. o Each user may have different personal information applicable to use of the device, either as related to particular services, or independent of them. -5.4. Usage of Outbound +5.4. Support for NATs PDSs that support devices behind NATs, and devices that can be behind NATs can use procedures specified in [I-D.ietf-sip-outbound]. The Outbound proxies can be configured or discovered. Clients that support such behavior MUST include the 'outbound' option-tag in a Supported header field value, and add the "ob" parameter as specified in [I-D.ietf-sip-outbound] within the SIP SUBSCRIBE for profile enrollment. 6. Event Package Definition @@ -1367,28 +1365,30 @@ sub-sections. 6.2.1. profile-type The "profile-type" parameter is used to indicate the token name of the profile type the user agent wishes to obtain and to be notified of subsequent changes. This document defines three logical types of profiles and their token names. They are as follows: local-network: specifying the "local-network" type profile indicates - the desire for profile data specific to the local network. + the desire for profile data, and potentially, profile change + notifications specific to the local network. device: specifying the "device" type profile(s) indicates the desire - for the profile data and profile change notification that is - specific to the device or user agent. + for the profile data, and potentially, profile change notification + that is specific to the device or user agent. user: Specifying "user" type profile indicates the desire for the - profile data and profile change notification specific to the user. + profile data, and potentially, profile change notification + specific to the user. The profile type is identified in the Event header parameter: "profile-type". A separate SUBSCRIBE dialog is used for each profile type. Thus, the subscription dialog on which a NOTIFY arrives implies which profile's data is contained in, or referred to, by the NOTIFY message body. The Accept header of the SUBSCRIBE request MUST include the MIME types for all profile content types for which the subscribing user agent wishes to retrieve profiles, or receive change notifications. @@ -1431,23 +1431,25 @@ The "effective-by" parameter in the Event header of the NOTIFY request specifies the maximum number of seconds before the user agent must attempt to make the new profile effective. The "effective-by" parameter MAY be provided in the NOTIFY request for any of the profile types. A value of 0 (zero) indicates that the subscribing user agent must attempt to make the profiles effective immediately (despite possible service interruptions). This gives the PDS the power to control when the profile is effective. This may be important to resolve an emergency problem or disable a user agent - immediately. The "effective-by" parameter is ignored in all messages - other than the NOTIFY request. In the following ABNF, EQUAL and - DIGIT are defined in [RFC3261]. + immediately. If it is absent, the device SHOULD attempt to make the + profile data effective at the earliest possible opportunity that does + not disrupt any services being offered. The "effective-by" parameter + is ignored in all messages other than the NOTIFY request. In the + following ABNF, EQUAL and DIGIT are defined in [RFC3261]. Effective-By = "effective-by" EQUAL 1*DIGIT 6.2.4. Summary of event parameters The following are example Event headers which may occur in SUBSCRIBE requests. These examples are not intended to be complete SUBSCRIBE requests. Event: ua-profile;profile-type=device; @@ -1486,21 +1489,21 @@ profile-type || device | user | local-network ============================================= vendor || | | model || | | version || | | effective-by || o | o | o 6.3. SUBSCRIBE Bodies This package defines no use of the SUBSCRIBE request body. If - present, it SHOULD be ignored. The exception being future + present, it SHOULD be ignored. Exceptions include future enhancements to the framework which may specify a use for the SUBSCRIBE request body. 6.4. Subscription Duration The duration of a subscription is specific to SIP deployments and no specific recommendation is made by this Event Package. If absent, a value of 86400 seconds (24 hours; 1 day) is RECOMMENDED since the presence (or absence) of a device subscription is not time critical to the regular functioning of the PDS. @@ -1509,24 +1512,24 @@ subscription, can be accomplished by setting the 'Expires' parameter to a value of Zero, as specified in [RFC3265]. 6.5. NOTIFY Bodies The framework specifying the Event Package allows for the NOTIFY body to contain the profile data, or a pointer to the profile data using content indirection. For profile data delivered via content indirection, i.e., a pointer to a PCC, then the Content-ID MIME header, as described in [RFC4483] MUST be used for each Profile - document URI. At a minimum, the "http:" and "https:" URI schemes - MUST be supported; other URI schemes MAY be supported based on the - Profile Data Frameworks (examples include FTP [RFC0959], HTTP - [RFC2616], HTTPS [RFC2818], LDAP [RFC4510] and XCAP [RFC4825] ). + document URI. At a minimum, the "http:" [RFC2616] and "https:" + [RFC2818] URI schemes MUST be supported; other URI schemes MAY be + supported based on the Profile Data Frameworks (examples include FTP + [RFC0959], LDAP [RFC4510] and XCAP [RFC4825] ). A non-empty NOTIFY body MUST include a MIME type specified in the 'Accept' header of the SUBSCRIBE. Further, if the Accept header of the SUBSCRIBE included the MIME type message/external-body (indicating support for content indirection) then the PDS MAY use content indirection in the NOTIFY body for providing the profiles. 6.6. Notifier Processing of SUBSCRIBE Requests A successful SUBSCRIBE request results in a NOTIFY with either @@ -1537,39 +1540,38 @@ Notifier is configured to accept such requests. The Notifier MAY also authenticate SUBSCRIBE messages even if the NOTIFY is expected to only contain a pointer to profile data. Securing data sent via Content Indirection is covered in Section 9. If the profile type indicated in the "profile-type" Event header parameter is unavailable or the Notifier is configured not to provide it, the Notifier SHOULD return a 404 response to the SUBSCRIBE request. If the specific user or device is unknown, the Notifier MAY - either accept or reject the subscription. + either accept or reject the subscription with a 403 response. 6.7. Notifier Generation of NOTIFY Requests As specified in [RFC3265], the Notifier MUST always send a NOTIFY request upon accepting a subscription. If the device or user is unknown and the Notifier chooses to accept the subscription, the Notifier MAY either respond with profile data (e.g., default profile - data) or provide no profile information (i.e. no body or content - indirection). + data) or provide no profile information (i.e., empty NOTIFY). - If the URI in the SUBSCRIBE request is a known identity and the - requested profile information is available (i.e. as specified in the - profile-type parameter of the Event header), the Notifier SHOULD send - a NOTIFY with profile data. Profile data MAY be sent as profile - contents or via Content Indirection (if the content indirection MIME - type was included in the Accept header). The Notifier MUST NOT use - any scheme that was not indicated in the "schemes" Contact header - field. + If the identity indicated in the SUBSCRIBE request (From header) is a + known identity and the requested profile information is available + (i.e. as specified in the profile-type parameter of the Event + header), the Notifier SHOULD send a NOTIFY with profile data. + Profile data MAY be sent as profile contents or via Content + Indirection (if the content indirection MIME type was included in the + Accept header). The Notifier MUST NOT use any scheme that was not + indicated in the "schemes" Contact header field. The Notifier MAY specify when the new profiles must be made effective by the Subscriber by specifying a maximum time in seconds (zero or more) in the "effective-by" event header parameter. If the SUBSCRIBE was received over an integrity protected SIP communications channel, the Notifier SHOULD send the NOTIFY over the same channel. 6.8. Subscriber Processing of NOTIFY Requests @@ -1581,26 +1583,27 @@ effective within the specified time. Exceptions include deployments that prohibit such behavior in certain cases (e.g., emergency sessions are in progress). When profile data cannot be applied within the recommended timeframe and this affects device behavior, any actions to be taken SHOULD be defined by the profile data definitions. By default, the Subscriber is RECOMMENDED to make the profiles effective as soon as possible. When accepting content indirection, the Subscriber MUST always support "http:" or "https:" and be prepared to accept NOTIFY messages - with those URI schemes. The Subscriber wishes to support alternative - URI schemes it MUST be indicated in the "schemes" Contact header - field parameter as defined in [RFC4483]. The Subscriber MUST also be - prepared to receive a NOTIFY request with no body. The subscriber - MUST NOT reject the NOTIFY request with no body. The subscription - dialog MUST NOT be terminated by a NOTIFY with no body. + with those URI schemes. If the Subscriber wishes to support + alternative URI schemes they MUST each be indicated in the "schemes" + Contact header field parameter as defined in [RFC4483]. The + Subscriber MUST also be prepared to receive a NOTIFY request with no + body. The subscriber MUST NOT reject the NOTIFY request with no + body. The subscription dialog MUST NOT be terminated by a empty + NOTIFY, i.e., with no body. 6.9. Handling of Forked Requests This Event package allows the creation of only one dialog as a result of an initial SUBSCRIBE request as described in section 4.4.9 of [RFC3265]. It does not support the creation of multiple subscriptions using forked SUBSCRIBE requests. 6.10. Rate of Notifications @@ -1609,25 +1612,23 @@ Package specification does not specify a throttling or minimum period between NOTIFY requests 6.11. State Agents State agents are not applicable to this Event Package. 7. Examples This section provides examples along with sample SIP message bodies - relevant to this framework. Both the examples are derived from a - snapshot of Section 4.1, specifically the request for the device - profile. The examples are purely informative and in case of - conflicts with the framework or protocols used for illustration, the - latter should be deemed normative. + relevant to this framework. Both the examples are derived from the + use case illustrated in Section 4.1, specifically the request for the + device profile. The examples are informative only. 7.1. Example 1: Device requesting profile This example illustrates the detailed message flows between the device and the SIP Service Provider's network for requesting and retrieving the profile (the flow uses the device profile as an example). The following are assumed for this example: @@ -1686,27 +1687,26 @@ framework. * Note: Some of the header fields (e.g., SUBSCRIBE, Event, via) are continued on a separate line due to format constraints of this document. SUBSCRIBE sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB @example.com SIP/2.0 Event: ua-profile;profile-type=device;vendor="vendor.example.net"; model="Z100";version="1.2.3"; - From: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB - @example.com;tag=1234 + From: anonymous@example.com;tag=1234 To: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com Call-ID: 3573853342923422@192.0.2.44 CSeq: 2131 SUBSCRIBE Contact: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB - @example.com + @192.168.1.44 ;+sip.instance="" ;schemes="http,https" Via: SIP/2.0/TCP 192.0.2.41; branch=z9hG4bK6d6d35b6e2a203104d97211a3d18f57a Accept: message/external-body, application/x-z100-device-profile Content-Length: 0 (SRes) the SUBSCRIBE request is received by a SIP Proxy in the Service @@ -1716,26 +1716,26 @@ secure communications channel (e.g., TLS). (NTFY) subsequently, the PDS transmits a SIP NOTIFY message indicating the profile location * Note: Some of the fields (e.g., content-type) are continued on a separate line due to format constraints of this document. NOTIFY sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB - @192.0.2.44 SIP/2.0 + @192.168.1.44 SIP/2.0 Event: ua-profile;effective-by=3600 From: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com ;tag=abca To: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com - ;tag=1231 + ;tag=1234 Call-ID: 3573853342923422@192.0.2.44 CSeq: 322 NOTIFY Via: SIP/2.0/UDP 192.0.2.3; branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d0 MIME-Version: 1.0 Content-Type: message/external-body; access-type="URL"; expiration="Mon, 01 Jan 2010 09:00:00 UTC"; URL="http://example.com/z100-000000000000.html"; size=9999; hash=10AB568E91245681AC1B @@ -1871,21 +1871,21 @@ (A-RS) Device A accepts the NOTIFY and sends a 200 OK (B-NT) PDS transmits a NOTIFY message to device B indicating the changed profile. A sample message is shown below: Note: Some of the fields (e.g., Via) are continued on a separate line due to format constraints of this document. NOTIFY sip:userX@192.0.2.43 SIP/2.0 Event: ua-profile;effective-by=3600 From: sip:userX@sip.example.net;tag=abce - To: sip:userX@sip.example.net.net;tag=1235 + To: sip:userX@sip.example.net.net;tag=1234 Call-ID: 3573853342923422@192.0.2.43 CSeq: 322 NOTIFY Via: SIP/2.0/UDP 192.0.2.3; branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d2 MIME-Version: 1.0 Content-Type: message/external-body; access-type="URL"; expiration="Mon, 01 Jan 2010 09:00:00 UTC"; URL="http://www.example.com/user-x-profile.html"; size=9999; hash=123456789AAABBBCCCDD @@ -1957,211 +1957,190 @@ CONTACT: ------- sumanth@cablelabs.com Daniel Petrie dan.ietf AT SIPez DOT com Note to RFC editor: Please replace RFCXXXX with the RFC number assigned to this document. 9. Security Considerations - The framework specified in this document enables profile data - delivery to devices. It specifies profile delivery stages, an event - package and several profile types. - - There are three stages: Enrollment, Content Retrieval, and Change - Notification. - - +------+ +-----+ - | | | | - |Device| | PNC | - | | | | - +------+ +-----+ - | | - | Profile Enrollment | - |---------------------->| - | | - | Initial Notification | - |<----------------------| - | | - - +------+ +-----+ - | | | | - |Device| | PNC | - | | | | - +------+ +-----+ - | | - | Profile Enrollment | - |---------------------->| - | | - | Change Notification | - |<----------------------| - | | - - +------+ +-----+ - | | | | - |Device| | PCC | - | | | | - +------+ +-----+ - | | - | Profile Request | (When content - |---------------------->| indirection - | | is used) - | Profile Response | - |<----------------------| - | | - - PNC = Profile Notification Component - PCC = Profile Content Component - Figure 23: Profile Delivery Stages + The framework specified in this documents specifies profile delivery + stages, an event package and three profile types to enable profile + delivery. The profile delivery stages are: enrollment, content + retrieval, and change notification. The event package helps with + enrollment and change notifications. Each profile type allows for + profile retrieval from a PDS belonging to a specific provider. - Enrollment allows a device to request a profile. To transmit the - request the device relies on configured, cached or discovered data. - Such data includes provider domain names, identities, and - credentials. The device either uses configured Outbound proxies or - discoveries the next-hop entity using [RFC3263] that can result in a - SIP proxy or the PDS. It then transmits the request, after - establishing a TLS session if required. If obtained via a SIP proxy, - the Request-URI is used to route it to a PDS (via an authoritative - SIP proxy, if required). + Enrollment allows a device to request, and if successful, enroll with + a PDS to obtain profile data. To transmit the request the device + relies on configured, cached or discovered data. Such data includes + provider domain names, identities, and credentials. The device + either uses configured outbound proxies or discovers the next-hop + entity using [RFC3263] that can result in a SIP proxy or the PDS. It + then transmits the request. A SIP Proxy receving the request uses + the Request-URI and event header contents to route it to a PDS (via + other SIP proxies, if required). When a PDS receives the enrollment request, it can either challenge - the presented identity (if any) or admit the enrollment. - Authorization then decides if the enrollment is accepted. If - accepted, the PDS sends an initial notification that contains either - the profile data, or content indirection information. The profile - data can contain information specific to an entity (such as the - device or a user) and may contain sensitive information (such as - credentials). Compromise of such data can lead to threats such as - impersonation attacks (establishing rogue sessions), theft of service - (if services are obtainable), and zombie attacks. Even if the - profile data is provided using content indirection, PCC information - within the notification can lead to threats such as denial of service - attacks (rogue devices bombard the PCC with requests for a specific - profile) and attempts to modify erroneous data onto the PCC (since - the location and format may be known). It is also important for the - device to ensure the authenticity of the PNC since impersonation of - the SIP service provider can lead to Denial of Service, Man-in-the- - Middle attacks, etc. + any contained identity or admit the enrollment. Authorization rules + then decide if the enrollment gets accepted. If accepted, the PDS + sends an initial notification that contains either the profile data, + or content indirection information. The profile data can contain + generic profile data (common across multiple devices) or information + specific to an entity (such as the device or a user). If specific to + an entity, it and may contain sensitive information such as + credentials. Compromise of sensitive data can lead to threats such + as impersonation attacks (establishing rogue sessions), theft of + service (if services are obtainable), and zombie attacks. Even if + the profile data is provided using content indirection, PCC + information within the notification can lead to threats such as + denial of service attacks (rogue devices bombard the PCC with + requests for a specific profile) and attempts to modify erroneous + data onto the PCC (since the location and format may be known). It + is also important for the device to ensure the authenticity of the + PNC since impersonation of the SIP service provider can lead to + Denial of Service and Man-in-the-Middle attacks. Profile content retrieval allows a device to retrieve profile data - from a PCC. This communication is accomplished using one of many - profile delivery protocols or frameworks, such as HTTP or HTTPS as - specified in this document. However, since the profile data returned - is subject to the same considerations as that sent via profile - notification, the same threats exist. + via content indirection from a PCC. This communication is + accomplished using one of many profile delivery protocols or + frameworks, such as HTTP or HTTPS as specified in this document. + However, since the profile data returned is subject to the same + considerations as that sent via profile notification, similar threats + exist. Thus, for the delivery of any sensitive profile data, + authentication of the entity requesting profile data is required. It + is also important for the requesting entity to authenticate the PDS + and ensure that the sensitive profile data is protected via message + integrity. For sensitive data that should not be subject to + snooping, privacy is also required. - Profile-specific considerations follow. + The following sub-sections highlight the security considerations that + are specific to each profile type. 9.1. Local-network profile A local network may or may not (e.g., home router) support local- network profiles as specified in this framework. Even if supported, the PDS may only be configured with a generic local-network profile - that is provided to every device capable of accessing the network. - Such a PDS may not implement any authentication requirements or TLS. + that is provided to every device that requests the local-network + profile. Such a PDS may not implement any authentication + requirements or TLS. Alternatively, certain deployments may require the entities - device - and the PDS - to mutually authenticate prior to profile enrollment. - Such networks may pre-configure user identities to the devices and - allow user-specific local-network profiles. In such networks the PDS - will contain X.509 certificates and support TLS, and the devices are - pre-configured with user identities, credentials and implement TLS. + and the PDS - to authenticate each other prior to succesful profile + enrollment. Such networks may pre-configure user identities to the + devices and allow user-specific local-network profiles. In such + networks the PDS will support digest, and the devices are configured + with user identities and credentials as specified in Section 5.3.1. + If sensitive profile data is being transmitted, the user identity is + a SIPS URI that results in TLS with the next-hop (which is + authenticated), and digest authentication is used by the PDS and the + device. - This framework supports both use cases and variations in-between. + This framework supports both use cases and any variations in-between. However, devices obtaining local-network profiles from an unauthenticated PDS are cautioned against potential MiM or PDS impersonation attacks. This framework requires that a device reject sensitive data, such as credentials, from unauthenticated local- - network sources (exceptions are noted). It also prohibits devices - from responding to authentication challenges from unauthenticated - PDSs. Responding to unauthenticated challenges allows for dictionary - attacks that can reveal weak passwords. - - If deployments prefer devices to obtain profiles only from pre- - configured domains (e.g., partner networks), they MAY require such - devices to establish TLS prior to obtaining the local-network - profile. + network sources. It also prohibits devices from responding to + authentication challenges in the absence of TLS. Responding to + unauthenticated challenges allows for dictionary attacks that can + reveal weak passwords. - The use of SIP Identity is useful in cases when TLS is not used but - the device still obtains a profile (e.g., the local-network profile). - In such cases the device provider, or the user, can use the SIP - Identity header to verify the source of the local-network profile. - However, the presence of the header does not guarantee the validity - of the data. It verifies the source and confirms data integrity, but - the data obtained from an undesired source may still be invalid - (e.g., it can be invalid or contain malicious content). + The use of SIP Identity is useful for the device to validate + notifications in the absence of a secure channel such as TLS. In + such cases the device can validate the SIP Identity header to verify + the source of the local-network profile. However, the presence of + the header does not guarantee the validity of the data. It verifies + the source and confirms data integrity, but the data obtained from an + undesired source may still be invalid, e.g., invalid outbound proxy + information, resulting in Denial of Service. Thus, devices + requesting the local-network profile from unknown networks need to be + prepared to discard information that prevent retrieval of other, + required, profiles. 9.2. Device profile Device profiles deal with device-specific configuration. They may be provided to unknown devices that are attempting to obtaining profiles - for purposes of trials and self-subscription to SIP services (not to - be confused with [RFC3265]), emergency services - ([I-D.ietf-ecrit-phonebcp]), or to devices that are known by the PDS. - Devices that are not aware of any device providers (i.e., no cached - or configured information) will have to discover a PDS in the network - they connect to. In such a case the discovered information may lead - them to a PDS that provides enough profile data to enable device - operation. This configuration can also provide a user AoR that can - be used in the local-network and credentials (temporary or long-term) - that will be used for future communication with the network. This - may enable the device to communicate with a device provider who - allows for self-subscription (e.g., web interface, interactive voice - response or customer service representative). It may also allow the - device a choice of device providers and allow the end-user to choose - one. It is to be noted that such devices are at the mercy of the - network they connect to initially. If they are initialized in a - rogue network, or get hijacked by a rogue PDS, the end-user may be - left without desired device operation, or worse unwanted operation. - To mitigate such factors the device provider may communicate - temporary credentials (PINs that can be entered via an interface) or - permanent credentials (e.g., a USB device) to the end-user for - connectivity. If such methods are used the large-entropy credentials - MUST be used, or quickly replaced with such, to minimize the impact - of dictionary attacks. Future enhancements to this framework may - specify device capabilities that allow for mutual authentication - without pre-configuration (e.g., X.509 certificates using PKI). + for purposes such as trials, self-subscription (not to be confused + with [RFC3265]) and emergency services ([I-D.ietf-ecrit-phonebcp]). - Once a device is associated with a device provider (either - dynamically or via pre-configuration using a user interface or prior - to distribution), the device profile is vital to device operation. - This is because the device profile can contain important operational - information such as users that are to be allowed access (white-list - or black-list), user credentials (if required) and other sensitive - information. Thus, it is also necessary to ensure that the device - profile is not obtained via an unauthenticated source or tampered - during transit. Thus the framework requires that devices supporting - any sensitive device profiles establish next-hop authenticated TLS - connections prior to device enrollment. However, given the - importance of the device profile it also allows for profile requests - in cases where the PDS does not implement TLS. It also allows the - PDSs to perform authentication without requiring TLS. However, this - leaves the communication open to MiM attacks and SHOULD be avoided. - Additionally any credential used SHOULD be of sufficiently large- - entropy to prevent dictionary attacks. Devices SHOULD use the - 'cnonce' parameter ([RFC2617]) to thwart "offline" dictionary - attacks. + This framework allows for the device profile to be used for + bootstrapping a device. Such boostrapping profile data may contain + enough information to connect to a Provider. For example, it may + enable the device to communicate with a device provider, allowing for + trial or self-subscription services via visual or audio interfaces + (e.g., interactive voice response), or customer service + representatives. The profile data may also allow the device a choice + of device providers and allow the end-user to choose one. The + profile data may also contain identities and credentials (temporary + or long-term) that can be used to obtain further profile data from + the network. If it contains such sensitive data, the framework + recommends the use of the SIP Identity header by the PDS. However, + to be able to validate the header, the device needs to be pre- + configured with the knowledge of allowable domains or certificates + for validation (e.g., using PKI). If not, the device can still + guarantee header and body integrity if the profile data contains the + domain certificate (but the data can still be invalid or malicious). + In such cases, devices supporting user interfaces may obtain + confirmation from the user trying to boostrap the device (confirming + header and body integrity). However, when the SIP Identity header is + not present, or the device is not capable of validating it, the + bootstrapping data is unauthenticated and obtained without any + integrity protection. Such bootstrapping data, however, may contain + only temporary credentials (SIPS URI and digest credentials) that can + be used to reconnect to the network to ensure message integrity and + privacy prior to obtaining long-term credentials. It is to be noted + that such devices are at the mercy of the network they request the + device profile from. If they are initialized in a rogue network, or + get hijacked by a rogue PDS, the end-user may be left without desired + device operation or, worse, unwanted operation. To mitigate such + factors the device provider may communicate temporary credentials + (PINs that can be entered via an interface) or permanent credentials + (e.g., a USB device) to the end-user for connectivity. If such + methods are used then large-entropy credentials MUST be used, or + quickly replaced with such, to minimize the impact of dictionary + attacks. Future enhancements to this framework may specify device + capabilities that allow for authentication without any pre- + configuration (e.g., X.509 certificates using PKI). Alternatively, a + PDS can use secure content indirection mechanisms such as HTTPS to + provide the bootstrapping data. + + Once a device is associated with a device provider the device profile + is vital to device operation. This is because the device profile can + contain important operational information such as users that are to + be allowed access (white-list or black-list), user credentials (if + required) and other sensitive information. Thus, it is necessary to + ensure that any device profile containing sensitive information is + obtained via an authenticated source, with integrity protection, and + delivered to an authenticated device. For sensitive information such + as credentials, privacy is also required. The framework requires + that devices obtain sensitive information only from authenticated + entities except while it is being bootstrapped. In cases where + privacy needs to be mandated for notifications, the device provider + can configure the device with a SIPS URI, to be used as the + subscription URI, during profile enrollment. The framework also + requires that a PDS presenting sensitive profile data to use digest + authentication. This ensures that the data is delivered to an + authenticated entity. Authentication of profile retrieval via + content indirection for sensitive profiles is via HTTPS. 9.3. User profile Devices can only request user profiles for users that are known by a - SIP service provider. Thus, PDSs are prohibited from accepting user - profile enrollment requests for users that are unknown in the - network. If the user AoR is a SIPS URI then the device is required - to establish a next-hop authenticated TLS session. This framework - requires this for profiles with sensitive data. If it is a SIP URI, - then the device is still recommended to attempt TLS establishment to - ensure protection against rogue PDSs. Further, the PDS will - authenticate requests prior to accepting profile enrollment requests - that can result in sensitive data. A mutually authenticated TLS - channel provides message integrity and privacy. + SIP service provider. PDSs are required to reject user profile + enrollment requests for any users that are unknown in the network. + For known user AoRs that are allowed to retrieve profiles, the + security considerations are similar to that of the device profile + (except for bootstrapping). 10. Acknowledgements The author appreciates all those who contributed and commented on the many iterations of this document. Detailed comments were provided by the following individuals: Jonathan Rosenberg from Cisco, Henning Schulzrinne from Columbia University, Cullen Jennings from Cisco, Rohan Mahy from Plantronics, Rich Schaaf from Pingtel, Volker Hilt from Bell Labs, Adam Roach of Estacado Systems, Hisham Khartabil from Telio, Henry Sinnreich from MCI, Martin Dolly from AT&T Labs, John @@ -2183,21 +2162,21 @@ from Counterpath, Alvin Jiang of Engin and Francois Audet from Nortel. The following SIPPING WG members are thanked for numerous reviews, comments and recommendations: John Elwell from Siemens, Donald Lukacs from Telcordia, Roni Even from Polycom, David Robbins from Verizon, Shida Schubert from NTT Advanced Technology Corporation, and Eugene Nechamkin from Broadcom. The editor would also like to extend a special thanks to the comments and recommendations provided by the SIPPING WG, specifically Keith Drage from Lucent (restructuring - proposal). + proposal) and John Elwell from Siemens. Additionally, appreciation is also due to Peter Koch for expert DNS advice. And finally, sincere appreciation is extended to the chairs (Mary Barnes from Nortel and Gonzalo Camarillo from Ericsson) and the Area Directors (Cullen Jennings from Cisco and Jon Peterson from Neustar) for facilitating discussions, reviews and contributions. 11. References