intarea P. Pfister Internet-Draft E. Vyncke, Ed. Intended status: Standards Track Cisco Expires: December 6, 2018 T. Pauly D. Schinazi Apple W. Shao Telecom-ParisTech June 4, 2018 Discovering Provisioning Domain Names and Data draft-ietf-intarea-provisioning-domains-02 Abstract An increasing number of hosts access the Internet via multiple interfaces or, in IPv6 multi-homed networks, via multiple IPv6 prefix configurations context. This document describes a way for hosts to identify such contexts, called Provisioning Domains (PvDs), where Fully Qualified Domain Names (FQDNs) act as PvD identifiers. Those identifiers are advertised in a new Router Advertisement (RA) option and, when present, are associated with the set of information included within the RA. Based on this FQDN, hosts can retrieve additional information about their network access characteristics via an HTTP over TLS query. This allows applications to select which Provisioning Domains to use as well as to provide configuration parameters to the transport layer and above. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months 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." Pfister, et al. Expires December 6, 2018 [Page 1] Internet-Draft Provisioning Domains June 2018 This Internet-Draft will expire on December 6, 2018. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Provisioning Domain Identification using Router Advertisements . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. PvD ID Option for Router Advertisements . . . . . . . . . 4 3.2. Router Behavior . . . . . . . . . . . . . . . . . . . . . 7 3.3. Non-PvD-aware Host Behavior . . . . . . . . . . . . . . . 8 3.4. PvD-aware Host Behavior . . . . . . . . . . . . . . . . . 8 3.4.1. DHCPv6 configuration association . . . . . . . . . . 9 3.4.2. DHCPv4 configuration association . . . . . . . . . . 9 3.4.3. Connection Sharing by the Host . . . . . . . . . . . 9 4. Provisioning Domain Additional Information . . . . . . . . . 10 4.1. Retrieving the PvD Additional Information . . . . . . . . 10 4.2. Operational Consideration to Providing the PvD Additional Information . . . . . . . . . . . . . . . . . . . . . . . 12 4.3. PvD Additional Information Format . . . . . . . . . . . . 12 4.3.1. Private Extensions . . . . . . . . . . . . . . . . . 13 4.3.2. Example . . . . . . . . . . . . . . . . . . . . . . . 13 4.4. Detecting misconfiguration and misuse . . . . . . . . . . 14 5. Operational Considerations . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 10.1. Normative references . . . . . . . . . . . . . . . . . . 18 10.2. Informative references . . . . . . . . . . . . . . . . . 19 Appendix A. Changelog . . . . . . . . . . . . . . . . . . . . . 20 A.1. Version 00 . . . . . . . . . . . . . . . . . . . . . . . 20 Pfister, et al. Expires December 6, 2018 [Page 2] Internet-Draft Provisioning Domains June 2018 A.2. Version 01 . . . . . . . . . . . . . . . . . . . . . . . 20 A.3. Version 02 . . . . . . . . . . . . . . . . . . . . . . . 21 A.4. WG Document version 00 . . . . . . . . . . . . . . . . . 22 A.5. WG Document version 01 . . . . . . . . . . . . . . . . . 22 A.6. WG Document version 02 . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 1. Introduction It has become very common in modern networks for hosts to access the internet through different network interfaces, tunnels, or next-hop routers. To describe the set of network configurations associated with each access method, the concept of Provisioning Domain (PvD) was defined in [RFC7556]. This document specifies a way to identify PvDs with Fully Qualified Domain Names (FQDN), called PvD IDs. Those identifiers are advertised in a new Router Advertisement (RA) [RFC4861] option called the PvD ID Router Advertisement option which, when present, associates the PvD ID with all the information present in the Router Advertisement as well as any configuration object, such as addresses, deriving from it. The PVD ID Router Advertisement option may also contain a set of other RA options. Since such options are only considered by hosts implementing this specification, network operators may configure hosts that are 'PvD-aware' with PvDs that are ignored by other hosts. Since PvD IDs are used to identify different ways to access the internet, multiple PvDs (with different PvD IDs) could be provisioned on a single host interface. Similarly, the same PvD ID could be used on different interfaces of a host in order to inform that those PvDs ultimately provide identical services. This document also introduces a way for hosts to retrieve additional information related to a specific PvD by means of an HTTP over TLS query using an URI derived from the PvD ID. The retrieved JSON object contains additional information that would typically be considered unfit, or too large, to be directly included in the Router Advertisement, but might be considered useful to the applications, or even sometimes users, when choosing which PvD should be used. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Pfister, et al. Expires December 6, 2018 [Page 3] Internet-Draft Provisioning Domains June 2018 In addition, this document uses the following terminology: Provisioning Domain (PvD): A set of network configuration information; for more information, see [RFC7556]. PvD ID: A Fully Qualified Domain Name (FQDN) used to identify a PvD. Explicit PvD: A PvD uniquely identified with a PvD ID. For more information, see [RFC7556]. Implicit PvD: A PvD that, in the absence of a PvD ID, is identified by the host interface to which it is attached and the address of the advertising router. See also [RFC7556]. PvD-aware host A host that supports the association of network configuration information into PvDs and the use of these PvDs. Also named PvD-aware node in [RFC7556]. 3. Provisioning Domain Identification using Router Advertisements Explicit PvDs are identified by a PvD ID. The PvD ID is a Fully Qualified Domain Name (FQDN) which MUST belong to the network operator in order to avoid naming collisions. The same PvD ID MAY be used in several access networks when they ultimately provide identical services (e.g., in all home networks subscribed to the same service); else, the PvD ID MUST be different to follow section 2.4 of [RFC7556]. 3.1. PvD ID Option for Router Advertisements This document introduces a Router Advertisement (RA) option called PvD option. It is used to convey the FQDN identifying a given PvD (see Figure 1), bind the PvD ID with configuration information received over DHCPv4 (see Section 3.4.2), enable the use of HTTP over TLS to retrieve the PvD Additional Information JSON object (see Section 4), as well as contain any other RA options which would otherwise be valid in the RA. Pfister, et al. Expires December 6, 2018 [Page 4] Internet-Draft Provisioning Domains June 2018 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |H|L|R| Reserved | Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... ... PvD ID FQDN ... ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... | Padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... ... Router Advertisement message header ... ... (Only present when R-flag is set) ... ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options ... +-+-+-+-+-+-+-+-+-+-+-+- Figure 1: PvD ID Router Advertisements Option format Type : (8 bits) Set to 21. Length : (8 bits) The length of the option in units of 8 octets, including the Type and Length fields, the Router Advertisement message header, if any, as well as the RA options that are included within the PvD Option. H-flag : (1 bit) 'HTTP' flag stating whether some PvD Additional Information is made available through HTTP over TLS, as described in Section 4. L-flag : (1 bit) 'Legacy' flag stating whether the router is also providing IPv4 information using DHCPv4 (see Section 3.4.2). R-flag : (1 bit) 'Router Advertisement' flag stating whether the PvD Option is followed (right after padding to the next 64 bits boundary) by a Router Advertisement message header (See section 4.2 of [RFC4861]). Delay : (4 bits) Unsigned integer used to delay HTTP GET queries from hosts by a randomized backoff (see Section 4.1). Reserved : (13 bits) Reserved for later use. It MUST be set to zero by the sender and ignored by the receiver. Sequence Number: (16 bits) Sequence number for the PvD Additional Information, as described in Section 4. Pfister, et al. Expires December 6, 2018 [Page 5] Internet-Draft Provisioning Domains June 2018 PvD ID FQDN : The FQDN used as PvD ID encoded in DNS format, as described in Section 3.1 of [RFC1035]. Domain names compression described in Section 4.1.4 of [RFC1035] MUST NOT be used. Padding : Zero or more padding octets to the next 8 octets boundary. It MUST be set to zero by the sender, and ignored by the receiver. RA message header : (16 octets) When the R-flag is set, a full Router Advertisement message header as specified in [RFC4861]. The 'Type', 'Code' and 'Checksum' fields (i.e. the first 32 bits), MUST be set to zero by the sender and ignored by the receiver. The other fields are to be set and parsed as specified in [RFC4861] or any updating documents. Options : Zero or more RA options that would otherwise be valid as part of the Router Advertisement main body, but are instead included in the PvD Option such as to be ignored by hosts that are not 'PvD-aware'. Here is an example of a PvD option with example.org as the PvD ID FQDN and including a RDNSS and prefix information options (it also have the sequence number 123, presence of additional information to be fetched with a delay indicated as 5): Pfister, et al. Expires December 6, 2018 [Page 6] Internet-Draft Provisioning Domains June 2018 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +---------------+-----------------------------------------------+ | Type: 21 | Length: 12 |1|0|0| Reserved |Delay:5| +---------------+-------------------------------+---------------+ | Seq number: 123 | 7 | e | +---------------+-----------------------------------------------+ | x | a | m | p | +---------------------------------------------------------------+ | l | e | 3 | o | +---------------------------------------------------------------+ | r | g | 0 | 0 (padding) | +---------------------------------------------------------------+ | 0 (padding) | 0 (padding) | 0 (padding) | 0 (padding) | +---------------+---------------+---------------+---------------+ | RDNSS option (RFC 6106) length: 5 ... ... ... ... | +---------------------------------------------------------------+ | Prefix Information Option (RFC 4861) length: 4 ... ... | ... | +---------------------------------------------------------------+ Figure 2 3.2. Router Behavior A router MAY send RAs containing one PvD option, but MUST NOT include more than one PvD option in each RA. In particular, the PvD option MUST NOT contain further PvD options. The PvD Option MAY contain zero, one, or more RA options which would otherwise be valid as part of the same RA. Such options are processed by PvD-aware hosts, while ignored by others. In order to provide multiple different PvDs, a router MUST send multiple RAs. Different explicit PvDs MAY be advertised with RAs using the same IPv6 source address; but different implicit PvDs, advertised by different RAs, MUST use different link-local addresses because these implicit PvDs are identified by the source addresses of the RAs. Whenever an RA, for a single PvD, would need to be sent via multiple packets, the PvD option header (i.e., all fields except the 'Options' field) MUST be repeated in all the transmitted RAs. But the options Pfister, et al. Expires December 6, 2018 [Page 7] Internet-Draft Provisioning Domains June 2018 within the 'Options' field, MAY be transmitted only once, included in one of the transmitted PvD options. 3.3. Non-PvD-aware Host Behavior As the PvD Option has a new option code, non-PvD-aware hosts will simply ignore the PvD Option and all the options it contains. This ensure the backward compatibility required in section 3.3 of [RFC7556]. This behavior allows for a mixed-mode network with a mix of PvD-aware and non-PvD-aware hosts coexist. 3.4. PvD-aware Host Behavior Hosts MUST associate received RAs and included configuration information (e.g., Router Valid Lifetime, Prefix Information [RFC4861], Recursive DNS Server [RFC8106], Routing Information [RFC4191] options) with the explicit PvD identified by the first PvD Option present in the received RA, if any, or with the implicit PvD identified by the host interface and the source address of the received RA otherwise. In case multiple PvD options are found in a given RA, hosts MUST ignore all but the first PvD option. Similarly, hosts MUST associate all network configuration objects (e.g., default routers, addresses, more specific routes, DNS Recursive Resolvers) with the PvD associated with the RA which last updated the object. For example, addresses that are generated using a received Prefix Information option (PIO) are associated with the PvD of the last received RA which included the given PIO. PvD IDs MUST be compared in a case-insensitive manner (i.e., A=a), assuming ASCII with zero parity while non-alphabetic codes must match exactly (see also Section 3.1 of [RFC1035]). For example, "pvd.example.com." or "PvD.Example.coM." would refer to the same PvD. While resolving names, executing the default address selection algorithm [RFC6724] or executing the default router selection algorithm when forwarding packets ([RFC2461], [RFC4191] and [RFC8028]), hosts MAY consider only the configuration associated with an arbitrary set of PvDs. For example, a host MAY associate a given process with a specific PvD, or a specific set of PvDs, while associating another process with another PvD. A PvD-aware application might also be able to select, on a per-connection basis, which PvDs should be used. In particular, constrained devices such as small battery operated devices (e.g. IoT), or devices with limited CPU or memory resources Pfister, et al. Expires December 6, 2018 [Page 8] Internet-Draft Provisioning Domains June 2018 may purposefully use a single PvD while ignoring some received RAs containing different PvD IDs. The way an application expresses its desire to use a given PvD, or a set of PvDs, or the way this selection is enforced, is out of the scope of this document. Useful insights about these considerations can be found in [I-D.kline-mif-mpvd-api-reqs]. 3.4.1. DHCPv6 configuration association When a host retrieves configuration elements using DHCPv6 (e.g., addresses or DNS recursive resolvers), they MUST be associated with the explicit or implicit PvD of the RA received on the same interface, sent from the same LLA, and with the O-flag or M-flag set [RFC4861]. If no such PvD is found, or whenever multiple different PvDs are found, the host behavior is unspecified. This process requires hosts to keep track of received RAs, associated PvD IDs, and routers LLA; it also assumes that the router either acts as a DHCPv6 server or relay and uses the same LLA for DHCPv6 and RA traffic (which may not be the case when the router uses VRRP to send its RA). 3.4.2. DHCPv4 configuration association When a host retrieves configuration elements from DHCPv4, they MUST be associated with the explicit PvD received on the same interface, whose PVD Options L-flag is set and, in the case of a non point-to- point link, using the same datalink address. If no such PvD is found, or whenever multiple different PvDs are found, the configuration elements coming from DHCPv4 MUST be associated with the implicit PvD identified by the interface on which the DHCPv4 transaction happened. The case of multiple explicit PvD for an IPv4 interface is undefined. 3.4.3. Connection Sharing by the Host The situation when a node receives an RA on one interface (e.g. cellular) and shares this connectivity by also acting as a router by transmitting RA on another interface (e.g. WiFi) is known as 'tethering'. It can be done as ND proxy. The exact behavior is out of scope of this document but it is expected that the one or several PvD associated to the shared interface (e.g. cellular) will also be advertised to the clients on the other interface (e.g. WiFi). Pfister, et al. Expires December 6, 2018 [Page 9] Internet-Draft Provisioning Domains June 2018 4. Provisioning Domain Additional Information Additional information about the network characteristics can be retrieved based on the PvD ID. This set of information is called PvD Additional Information, and is encoded as a JSON object [RFC7159]. The purpose of this additional set of information is to securely provide additional information to applications about the connectivity that is provided using a given interface and source address pair. It typically includes data that would be considered too large, or not critical enough, to be provided within an RA option. The information contained in this object MAY be used by the operating system, network libraries, applications, or users, in order to decide which set of PvDs should be used for which connection, as described in Section 3.4. 4.1. Retrieving the PvD Additional Information When the H-flag of the PvD Option is set, hosts MAY attempt to retrieve the PvD Additional Information associated with a given PvD by performing an HTTP over TLS [RFC2818] GET query to https:///.well-known/pvd [RFC5785]. Inversely, hosts MUST NOT do so whenever the H-flag is not set. Note that the DNS name resolution of the PvD ID, the PKI checks as well as the actual query MUST be performed using the considered PvD. In other words, the name resolution, PKI checks, source address selection, as well as the next-hop router selection MUST be performed while using exclusively the set of configuration information attached with the PvD, as defined in Section 3.4. In some cases, it may therefore be necessary to wait for an address to be available for use (e.g., once the Duplicate Address Detection or DHCPv6 processes are complete) before initiating the HTTP over TLS query. If the host has a temporary address per [RFC4941] in this PvD, then hosts SHOULD use a temporary address to fetch the PvD Additional Information and SHOULD deprecate the used temporary address and generate a new temporary address afterward. If the HTTP status of the answer is greater than or equal to 400 the host MUST abandon and consider that there is no additional PvD information. If the HTTP status of the answer is between 300 and 399, inclusive, it MUST follow the redirection(s). If the HTTP status of the answer is between 200 and 299, inclusive, the host MAY get a file containing a single JSON object. When a JSON object could not be retrieved, an error message SHOULD be logged and/or displayed in a rate-limited fashion. Pfister, et al. Expires December 6, 2018 [Page 10] Internet-Draft Provisioning Domains June 2018 After retrieval of the PvD Additional Information, hosts MUST keep track of the Sequence Number value received in subsequent RAs including the same PvD ID. In case the new value is greater than the value that was observed when the PvD Additional Information object was retrieved (using serial number arithmetic comparisons [RFC1982]), or whenever the validity time included in the PVD Additional Information JSON object is expired, hosts MUST either perform a new query and retrieve a new version of the object, or, failing that, deprecate the object and stop using the additional information provided in the JSON object. Hosts retrieving a new PvD Additional Information object MUST check for the presence and validity of the mandatory fields specified in Section 4.3. A retrieved object including an expiration time that is already past or missing a mandatory element MUST be ignored. In order to avoid synchronized queries toward the server hosting the PvD Additional Information when an object expires, object updates are delayed by a randomized backoff time. When a host performs an object update after it detected a change in the PvD Option Sequence number, it MUST delay the query by a random time between zero and 2**(Delay * 2) milliseconds, where 'Delay' corresponds to the 4 bits long unsigned integer in the last received PvD Option. When a host last retrieved an object at time A including a validity time B, and is configured to keep the object up to date, it MUST perform the update at a uniformly random time in the interval [(B-A)/2,B]. In the example Figure 2, the delay field value is 5, this means that host MUST delay the query by a random number between 0 and 2**(5 * 2) milliseconds, i.e., between 0 and 1024 milliseconds. Since the 'Delay' value is directly within the PvD Option rather than the object itself, an operator may perform a push-based update by incrementing the Sequence value while changing the Delay value depending on the criticality of the update and its PvD Additional Information servers capacity. The PvD Additional Information object includes a set of IPv6 prefixes (under the key "prefixes") which MUST be checked against all the Prefix Information Options advertised in the RA. If any of the prefixes included in the PIO is not covered by at least one of the listed prefixes, the PvD associated with the tested prefix MUST be considered unsafe and MUST NOT be used. While this does not prevent Pfister, et al. Expires December 6, 2018 [Page 11] Internet-Draft Provisioning Domains June 2018 a malicious network provider, it does complicate some attack scenarios, and may help detecting misconfiguration. 4.2. Operational Consideration to Providing the PvD Additional Information Whenever the H-flag is set in the PvD Option, a valid PvD Additional Information object MUST be made available to all hosts receiving the RA by the network operator. In particular, when a captive portal is present, hosts MUST still be allowed to perform DNS, PKI and HTTP over TLS operations related to the retrieval of the object, even before logging into the captive portal. Routers MAY increment the PVD Option Sequence number in order to inform host that a new PvD Additional Information object is available and should be retrieved. The server providing the JSON files SHOULD also check whether the client address is part of the prefixes listed into the additional information and SHOULD return a 403 response code if there is no match. 4.3. PvD Additional Information Format The PvD Additional Information is a JSON object. The following table presents the mandatory keys which MUST be included in the object: +----------+-----------------+-------------+------------------------+ | JSON key | Description | Type | Example | +----------+-----------------+-------------+------------------------+ | name | Human-readable | UTF-8 | "Awesome Wifi" | | | service name | string | | | | | [RFC3629] | | | expires | Date after | [RFC3339] | "2017-07-23T06:00:00Z" | | | which this | | | | | object is not | | | | | valid | | | | prefixes | Array of IPv6 | Array of | ["2001:db8:1::/48", | | | prefixes valid | strings | "2001:db8:4::/48"] | | | for this PVD | | | +----------+-----------------+-------------+------------------------+ A retrieved object which does not include a valid string associated with the "name" key at the root of the object, or a valid date associated with the "expires" key, also at the root of the object, MUST be ignored. In such cases, an error message SHOULD be logged Pfister, et al. Expires December 6, 2018 [Page 12] Internet-Draft Provisioning Domains June 2018 and/or displayed in a rate-limited fashion. If the PIO of the received RA is not covered by at least one of the "prefixes" key, the retrieved object SHOULD be ignored. The following table presents some optional keys which MAY be included in the object. +---------------+-----------------+---------+-----------------------+ | JSON key | Description | Type | Example | +---------------+-----------------+---------+-----------------------+ | localizedName | Localized user- | UTF-8 | "Wifi Genial" | | | visible service | string | | | | name, language | | | | | can be selected | | | | | based on the | | | | | HTTP Accept- | | | | | Language header | | | | | in the request. | | | | dnsZones | DNS zones | array | ["example.com","sub.e | | | searchable and | of DNS | xample.org"] | | | accessible | zones | | | noInternet | No Internet, | boolean | true | | | set when the | | | | | PvD only | | | | | provides | | | | | restricted | | | | | access to a set | | | | | of services | | | +---------------+-----------------+---------+-----------------------+ It is worth noting that the JSON format allows for extensions. Whenever an unknown key is encountered, it MUST be ignored along with its associated elements. 4.3.1. Private Extensions JSON keys starting with "x-" are reserved for private use and can be utilized to provide information that is specific to vendor, user or enterprise. It is RECOMMENDED to use one of the patterns "x-FQDN- KEY" or "x-PEN-KEY" where FQDN is a fully qualified domain name or PEN is a private enterprise number [PEN] under control of the author of the extension to avoid collisions. 4.3.2. Example Here are two examples based on the keys defined in this section. Pfister, et al. Expires December 6, 2018 [Page 13] Internet-Draft Provisioning Domains June 2018 { "name": "Foo Wireless", "localizedName": "Foo-France Wifi", "expires": "2017-07-23T06:00:00Z", "prefixes" : ["2001:db8:1::/48", "2001:db8:4::/48"], } { "name": "Bar 4G", "localizedName": "Bar US 4G", "expires": "2017-07-23T06:00:00Z", "prefixes": ["2001:db8:1::/48", "2001:db8:4::/48"], } 4.4. Detecting misconfiguration and misuse When a host retrieves the PvD Additional Information, it MUST verify that the TLS server certificate is valid for the performed request (e.g., that the Subject Name is equal to the PvD ID expressed as an FQDN). This authentication creates a secure binding between the information provided by the trusted Router Advertisement, and the HTTPS server. But this does not mean the Advertising Router and the PvD server belong to the same entity. Hosts MUST verify that all prefixes in the RA PIO are covered by a prefix from the PvD Additional Information. An adversarial router willing to fake the use of a given explicit PvD, without any access to the actual PvD Additional Information, would need to perform NAT66 in order to circumvent this check. It is also RECOMMENDED that the HTTPS server checks the source addresses of incoming connections (see Section 4.1). This check give reasonable assurance that neither NPTv6 [RFC6296] nor NAT66 were used and restricts the information to the valid network users. 5. Operational Considerations This section describes some use cases of PvD. For the sake of simplicity, the RA messages will not be described in the usual ASCII art but rather in an indented list. For example, a RA message containing some options and a PvD option that also contains other options will be described as: o RA Header: router lifetime = 6000 o Prefix Information Option: length = 4, prefix = 2001:db8:cafe::/64 Pfister, et al. Expires December 6, 2018 [Page 14] Internet-Draft Provisioning Domains June 2018 o PvD Option header: length = 3+ 5 +4 , PvD ID FQDN = example.org., R-flag = 0 (actual length of the header with padding 24 bytes = 3 * 8 bytes) * Recursive DNS Server: length = 5, addresses= [2001:db8:cafe::53, 2001:db8:f00d::53] * Prefix Information Option: length = 4, prefix = 2001:db8:f00d::/64 It is expected that for some years, networks will have a mixed environment of PvD-aware hosts and non-PvD-aware hosts. If there is a need to give specific information to PvD-aware hosts only, then it is recommended to send TWO RA messages: one for each class of hosts. For example, here is the RA for non-PvD-aware hosts: o RA Header: router lifetime = 6000 (non-PvD-aware hosts will use this router as a default router) o Prefix Information Option: length = 4, prefix = 2001:db8:cafe::/64 o Recursive DNS Server Option: length = 3, addresses= [2001:db8:cafe::53] o PvD Option header: length = 3+ 2, PvD ID FQDN = foo.example.org., R-flag = 1 (actual length of the header 24 bytes = 3 * 8 bytes) * RA Header: router lifetime = 0 (PvD-aware hosts will not use this router as a default router), implicit length = 2 And here is a RA example for PvD-aware hosts: o RA Header: router lifetime = 0 (non-PvD-aware hosts will not use this router as a default router) o PvD Option header: length = 3+ 2 + 4 + 3, PvD ID FQDN = example.org., R-flag = 1 (actual length of the header 24 bytes = 3 * 8 bytes) * RA Header: router lifetime = 1600 (PvD-aware hosts will use this router as a default router), implicit length = 2 * Prefix Information Option: length = 4, prefix = 2001:db8:f00d::/64 * Recursive DNS Server Option: length = 3, addresses= [2001:db8:f00d::53] Pfister, et al. Expires December 6, 2018 [Page 15] Internet-Draft Provisioning Domains June 2018 In the above example, non-PvD-aware hosts will only use the first RA sent from their default router and using the 2001:db8:cafe::/64 prefix. PvD-aware hosts will autonomously configure addresses from both PIOs, but will only use the source address in 2001:db8:f00d::/64 to communicate past the first hop router since only the router sending the second RA will be used as default router; similarly, they will use the DNS server 2001:db8:f00d::53 when communicating with this adress. 6. Security Considerations Although some solutions such as IPsec or SeND [RFC3971] can be used in order to secure the IPv6 Neighbor Discovery Protocol, in practice actual deployments largely rely on link layer or physical layer security mechanisms (e.g. 802.1x [IEEE8021X]) in conjunction with RA Guard [RFC6105]. This specification does not improve the Neighbor Discovery Protocol security model, but extends the purely link-local trust relationship between the host and the default routers with HTTP over TLS communications which servers are authenticated as rightful owners of the FQDN received within the trusted PvD ID RA option. It must be noted that Section 4.4 of this document only provides reasonable assurance against misconfiguration but does not prevent an hostile network access provider to advertize wrong information that could lead applications or hosts to select an hostile PvD. Users should always apply caution when connecting to an unknown network. 7. Privacy Considerations Retrieval of the PvD Additional Information over HTTPS requires early communications between the connecting host and a server which may be located further than the first hop router. Although this server is likely to be located within the same administrative domain as the default router, this property can't be ensured. Therefore, hosts willing to retrieve the PvD Additional Information before using it without leaking identity information, SHOULD make use of an IPv6 Privacy Address and SHOULD NOT include any privacy sensitive data, such as User Agent header or HTTP cookie, while performing the HTTP over TLS query. From a privacy perspective, retrieving the PvD Additional Information is not different from establishing a first connection to a remote server, or even performing a single DNS lookup. For example, most operating systems already perform early queries to well known web sites, such as http://captive.example.com/hotspot-detect.html, in order to detect the presence of a captive portal. Pfister, et al. Expires December 6, 2018 [Page 16] Internet-Draft Provisioning Domains June 2018 There may be some cases where hosts, for privacy reasons, should refrain from accessing servers that are located outside a certain network boundary. In practice, this could be implemented as a whitelist of 'trusted' FQDNs and/or IP prefixes that the host is allowed to communicate with. In such scenarios, the host SHOULD check that the provided PvD ID, as well as the IP address that it resolves into, are part of the allowed whitelist. 8. IANA Considerations Upon publication of this document, IANA is asked to remove the 'reclaimable' tag off the value 21 for the PvD option (from the IPv6 Neighbor Discovery Option Formats registry). IANA is asked to assign the value "pvd" from the Well-Known URIs registry. IANA is asked to create and maintain a new registry entitled "Additional Information PvD Keys" containing ASCII strings. The initial content of this registry are given in Section 4.3; future assignments are to be made through Expert Review [BCP36]. Finally, IANA is asked to create and maintain a new registry entitled "PvD option Flags" reserving bit positions from 0 to 15 to be used in the PvD option bitmask. Bit position 0, 1 and 2 are reserved by this document (as specified in Figure 1). Future assignments require a Standard Track RFC document. 9. Acknowledgements Many thanks to M. Stenberg and S. Barth for their earlier work: [I-D.stenberg-mif-mpvd-dns], as well as to Basile Bruneau who was author of an early version of this document. Thanks also to Marcus Keane, Mikael Abrahamson, Ray Bellis, Zhen Cao, Tim Chow, Lorenzo Colitti, Ian Farrer, Bob Hinden, Tatuya Jinmei, Erik Kline, Ted Lemon, Jen Lenkova, Veronika McKillop, Mark Townsley and James Woodyatt for useful and interesting discussions. Finally, special thanks to Thierry Danis and Wenqin Shao for their valuable inputs and implementation efforts ([github]), Tom Jones for his integration effort into the NEAT project and Rigil Salim for his implementation work. Pfister, et al. Expires December 6, 2018 [Page 17] Internet-Draft Provisioning Domains June 2018 10. References 10.1. Normative references [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987, . [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, DOI 10.17487/RFC1982, August 1996, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, DOI 10.17487/RFC2461, December 1998, . [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, . [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 2003, . [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, DOI 10.17487/RFC4861, September 2007, . [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . Pfister, et al. Expires December 6, 2018 [Page 18] Internet-Draft Provisioning Domains June 2018 10.2. Informative references [github] Cisco, "IPv6-mPvD github repository", . [I-D.kline-mif-mpvd-api-reqs] Kline, E., "Multiple Provisioning Domains API Requirements", draft-kline-mif-mpvd-api-reqs-00 (work in progress), November 2015. [I-D.stenberg-mif-mpvd-dns] Stenberg, M. and S. Barth, "Multiple Provisioning Domains using Domain Name System", draft-stenberg-mif-mpvd-dns-00 (work in progress), October 2015. [IEEE8021X] IEEE, "IEEE Standards for Local and Metropolitan Area Networks: Port based Network Access Control, IEEE Std". [PEN] IANA, "Private Enterprise Numbers", . [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, . [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, DOI 10.17487/RFC3971, March 2005, . [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, November 2005, . [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, . [RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known Uniform Resource Identifiers (URIs)", RFC 5785, DOI 10.17487/RFC5785, April 2010, . Pfister, et al. Expires December 6, 2018 [Page 19] Internet-Draft Provisioning Domains June 2018 [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, DOI 10.17487/RFC6105, February 2011, . [RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix Translation", RFC 6296, DOI 10.17487/RFC6296, June 2011, . [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, "Default Address Selection for Internet Protocol Version 6 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, . [RFC6731] Savolainen, T., Kato, J., and T. Lemon, "Improved Recursive DNS Server Selection for Multi-Interfaced Nodes", RFC 6731, DOI 10.17487/RFC6731, December 2012, . [RFC7556] Anipko, D., Ed., "Multiple Provisioning Domain Architecture", RFC 7556, DOI 10.17487/RFC7556, June 2015, . [RFC8028] Baker, F. and B. Carpenter, "First-Hop Router Selection by Hosts in a Multi-Prefix Network", RFC 8028, DOI 10.17487/RFC8028, November 2016, . [RFC8106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli, "IPv6 Router Advertisement Options for DNS Configuration", RFC 8106, DOI 10.17487/RFC8106, March 2017, . Appendix A. Changelog Note to RFC Editors: Remove this section before publication. A.1. Version 00 Initial version of the draft. Edited by Basile Bruneau + Eric Vyncke and based on Basile's work. A.2. Version 01 Major rewrite intended to focus on the the retained solution based on corridors, online, and WG discussions. Edited by Pierre Pfister. The following list only includes major changes. Pfister, et al. Expires December 6, 2018 [Page 20] Internet-Draft Provisioning Domains June 2018 PvD ID is an FQDN retrieved using a single RA option. This option contains a sequence number for push-based updates, a new H-flag, and a L-flag in order to link the PvD with the IPv4 DHCP server. A lifetime is included in the PvD ID option. Detailed Hosts and Routers specifications. Additional Information is retrieved using HTTP-over-TLS when the PvD ID Option H-flag is set. Retrieving the object is optional. The PvD Additional Information object includes a validity date. DNS-based approach is removed as well as the DNS-based encoding of the PvD Additional Information. Major cut in the list of proposed JSON keys. This document may be extended later if need be. Monetary discussion is moved to the appendix. Clarification about the 'prefixes' contained in the additional information. Clarification about the processing of DHCPv6. A.3. Version 02 The FQDN is now encoded with ASCII format (instead of DNS binary) in the RA option. The PvD ID option lifetime is removed from the object. Use well known URI "https:///.well-known/pvd" Reference RFC3339 for JSON timestamp format. The PvD ID Sequence field has been extended to 16 bits. Modified host behavior for DHCPv4 and DHCPv6. Removed IKEv2 section. Removed mention of RFC7710 Captive Portal option. A new I.D. will be proposed to address the captive portal use case. Pfister, et al. Expires December 6, 2018 [Page 21] Internet-Draft Provisioning Domains June 2018 A.4. WG Document version 00 Document has been accepted as INTAREA working group document IANA considerations follow RFC8126 [RFC8126] PvD ID FQDN is encoded as per RFC 1035 [RFC1035] PvD ID FQDN is prepended by a one-byte length field Marcus Keane added as co-author dnsZones key is added back draft of a privacy consideration section and added that a temporary address should be used to retrieve the PvD additional information per Bob Hinden's request: the document is now aiming at standard track and security considerations have been moved to the main section A.5. WG Document version 01 Removing references to 'metered' and 'characteristics' keys. Those may be in scope of the PvD work, but this document will focus on essential parts only. Removing appendix section regarding link quality and billing information. The PvD RA Option may now contain other RA options such that PvD- aware hosts may receive configuration information otherwise invisible to non-PvD-aware hosts. Clarify that the additional PvD Additional Information is not intended to modify host's networking stack behavior, but rather provide information to the Application, used to select which PvDs must be used and provide configuration parameters to the transport layer. The RA option padding is used to increase the option size to the next 64 (was 32) bits boundary. Better detail the Security model and Privacy considerations. Pfister, et al. Expires December 6, 2018 [Page 22] Internet-Draft Provisioning Domains June 2018 A.6. WG Document version 02 Use the IANA value of 21 in the text and update the IANA considerations section accordingly add the Delay field to avoid the thundering herd effect add Wenqin Shao as author keep the 1 PvD per RA model changed the intro (per Zhen Cao) "when choosing which PvD and transport should be used" => "when choosing which PvD should be used" rename A-flag in R-flag to avoid A-flag of PIO use the wording "PvD Option", removing the ID token as it is now a container with more then just an ID, removing 'RA' in the option name to be consistent with other IANA NDP option use "non-PvD-aware" rather than "PvD-ignorant" added more reference to RFC 7556 (notably for PvD being globally unique, introducing PvD-aware host vs. PvD-aware node) Section 3.4.3 renamed from "interconnection shared by node" to 'connection shared by node" Section 3.4 renamed into "PvD-aware Host Behavior" Added a section "Non-PvD-aware Host Behavior" Authors' Addresses Pierre Pfister Cisco 11 Rue Camille Desmoulins Issy-les-Moulineaux 92130 France Email: ppfister@cisco.com Pfister, et al. Expires December 6, 2018 [Page 23] Internet-Draft Provisioning Domains June 2018 Eric Vyncke (editor) Cisco De Kleetlaan, 6 Diegem 1831 Belgium Email: evyncke@cisco.com Tommy Pauly Apple Email: tpauly@apple.com David Schinazi Apple Email: dschinazi@apple.com Wenqin Shao Telecom-ParisTech France Email: wenqin.shao@telecom-paristech.fr Pfister, et al. Expires December 6, 2018 [Page 24]