RFC 8801
Discovering Provisioning Domain Names and Data
RFC 8801: Discovering Provisioning Domain Names and Data 🎀
Okay bestie, this one's from the IETF and it's on the Standards Track 📜, so it's an official spec, no cap. It's by P. Pfister and É. Vyncke (both Cisco), T. Pauly (Apple Inc.), D. Schinazi (Google LLC), and W. Shao (Cisco). It's dated July 2020 and has ISSN 2070-1721 🦋. The header doesn't list any RFCs that it obsoletes or updates, so nothing gets replaced here.
Abstract 💖
Provisioning Domains (PvDs) are basically consistent sets of network configuration information ✨. They let hosts juggle connections to multiple networks and interfaces at the same time, like when a home router gives you internet through both broadband and a cellular provider 🏠📶.
This doc defines a way to explicitly identify PvDs using a Router Advertisement (RA) option 🧚. The option announces a PvD identifier, so hosts can compare IDs and tell PvDs apart. The option can carry some info about a PvD directly, and it can optionally point to PvD Additional Information that you can fetch with HTTP over TLS 🔐.
Status of This Memo 📝
This is an Internet Standards Track document, so it's official 👑.
It's a product of the IETF, which means it represents the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check out Section 2 of RFC 7841 📚.
Info about the current status of this document, any errata, and how to give feedback is at https://www.rfc-editor.org/info/rfc8801 🔗.
Copyright Notice ©️
Copyright (c) 2020 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, since 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
1.1. Specification of Requirements
2. Terminology
3. Provisioning Domain Identification Using Router Advertisements
3.1. PvD Option for Router Advertisements
3.2. Router Behavior
3.3. Non-PvD-Aware Host Behavior
3.4. PvD-Aware Host Behavior
3.4.1. DHCPv6 Configuration Association
3.4.2. DHCPv4 Configuration Association
3.4.3. Connection Sharing by the Host
3.4.4. Usage of DNS Servers
4. Provisioning Domain Additional Information
4.1. Retrieving the PvD Additional Information
4.2. Operational Consideration to Providing the PvD Additional
Information
4.3. PvD Additional Information Format
4.3.1. Example
4.4. Detecting Misconfiguration and Misuse
5. Operational Considerations
5.1. Exposing Extra RA Options to PvD-Aware Hosts
5.2. Different RAs for PvD-Aware and Non-PvD-Aware Hosts
5.3. Enabling Multihoming for PvD-Aware Hosts
5.4. Providing Additional Information to PvD-Aware Hosts
6. Security Considerations
7. Privacy Considerations
8. IANA Considerations
8.1. Change to IPv6 Neighbor Discovery Option Formats Registry
8.2. New Entry in the Well-Known URIs Registry
8.3. New Additional Information PvD Keys Registry
8.4. New PvD Option Flags Registry
8.5. PvD JSON Media Type Registration
9. References
9.1. Normative References
9.2. Informative References
Acknowledgments
Authors' Addresses1. Introduction 🌸
Provisioning Domains (PvDs) are defined in [RFC7556] as consistent sets of network configuration information. That info includes properties that are usually tied to a single networking interface, like source addresses, DNS configuration, proxy configuration, and gateway addresses 💅.
Clients that are aware of PvDs can take advantage of multiple network interfaces at once. That means two PvDs can run in parallel, either for separate connections or for multi-path transports 🚀.
Most PvDs today are discovered implicitly, like when a host gets info through Router Advertisements from a router on the network it's directly connected to. But [RFC7556] also defines the notion of Explicit PvDs. IPsec Virtual Private Networks count as Explicit PvDs, but Explicit PvDs can also be discovered via the local network router. Discovering Explicit PvDs unlocks two key advancements for managing multiple PvDs:
- The ability to discover and use multiple PvDs on a single interface, such as when a local router can provide connectivity to two different Internet Service Providers.
- The ability to associate Additional Information about PvDs to describe the properties of the network.
While [RFC7556] defines the concept of Explicit PvDs, it doesn't define the mechanism for discovering multiple Explicit PvDs on a single network and their Additional Information 🙈.
This document specifies a way to identify PvDs with Fully Qualified Domain Names (FQDNs), called PvD IDs 🎀. Those identifiers are advertised in a new Router Advertisement (RA) [RFC4861] option called the PvD Option. When it's present, it associates the PvD ID with all the information in the Router Advertisement, plus any configuration object (like addresses) derived from it. The PvD Option may also contain a set of other RA options, along with an optional inner Router Advertisement message header. These options and the optional inner header are only visible to 'PvD-aware' hosts, so those hosts get a specialized view of the network configuration 👑.
Since PvD IDs are used to identify different ways to access the Internet, multiple PvDs (with different PvD IDs) can be provisioned on a single host interface. Similarly, the same PvD ID could be used on different interfaces of a host to show that those PvDs ultimately provide equivalent services 🦋.
This document also introduces a mechanism for hosts to retrieve optional Additional Information related to a specific PvD. They do it with an HTTP-over-TLS query using a URI derived from the PvD ID. The retrieved JSON object contains Additional Information that would usually be considered too large to be directly included in the Router Advertisement, but it might be useful to applications (or sometimes users) when they're choosing which PvD to use ✨.
Okay, here's an example. Say Alice has both a cellular network provider and a broadband provider at home. Her PvD-aware devices and applications would know about both available uplinks 📱. Those applications could fail over between these networks or run connections over both (potentially using multi-path transports). Applications could also pick specific uplinks based on the properties of the network. For instance, if the cellular network provides free high-quality video streaming, a video-streaming app could use that network while most of the other traffic on Alice's device uses the broadband provider 🎬💜.
1.1. Specification of Requirements 📏
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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
2. Terminology 📖
This document uses the following terminology, so let's get the vocab down bestie:
- 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 as described in this document. 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) that identifies the network operator. Network operators MUST use names that they own or manage to avoid naming conflicts 🫶. 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 Option for Router Advertisements ✨
okay bestie, this is the main event 🎀 The PvD Option is a brand new Router Advertisement (RA) option, and it's doing a LOT. It carries the FQDN that identifies a PvD (see Figure 1), ties the PvD ID to config received over DHCPv4 (see Section 3.4.2), turns on HTTP over TLS so the PvD Additional Information JSON object can be fetched (see Section 4), and can even hold any other RA options that would otherwise be valid in the RA. main character energy 💅
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 Option Format
Here's the breakdown of each field, no cap:
- Type: (8 bits) Set to 21. 🦋
- Length: (8 bits) The length of the option in units of 8 octets, counting the Type and Length fields, the Router Advertisement message header (if there is one), and the RA options that are included within the PvD Option.
- H-flag: (1 bit) The 'HTTP' flag. It says whether some PvD Additional Information is available through HTTP over TLS, as described in Section 4. 🌸
- L-flag: (1 bit) The 'Legacy' flag. It says whether the PvD is associated with IPv4 information assigned using DHCPv4 (see Section 3.4.2).
- R-flag: (1 bit) The 'Router Advertisement' flag. It says whether the PvD Option header is followed (right after padding to the next 64-bit boundary) by a Router Advertisement message header (see Section 4.2 of [RFC4861]). The inner message header gets used the way Section 3.4 describes.
- Reserved: (9 bits) Reserved for later use. It MUST be set to zero by the sender and ignored by the receiver. 🔒
- Delay: (4 bits) An unsigned integer used to delay HTTP GET queries from hosts by a randomized backoff (see Section 4.1). If the H-flag is not set, senders SHOULD set the delay to zero, and receivers SHOULD ignore the value. ⭐
- Sequence Number: (16 bits) The sequence number for the PvD Additional Information, as described in Section 4. If the H-flag is not set, senders SHOULD set the Sequence Number to zero, and receivers SHOULD ignore the value. 🍓
- PvD ID FQDN: The FQDN used as the PvD ID, encoded in DNS format, as described in Section 3.1 of [RFC1035]. Domain name compression as described in Section 4.1.4 of [RFC1035] MUST NOT be used. 🚫
- Padding: Zero or more padding octets, going up to the next 8-octet boundary (see Section 4.6 of [RFC4861]). 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, this is a full Router Advertisement message header as specified in [RFC4861]. The sender MUST set the Type field to 134 (the value for "Router Advertisement") and set the Code field to 0. Receivers MUST ignore both of these fields. The Checksum field MUST be set to 0 by the sender; non-zero checksums MUST be ignored by the receiver without causing the processing of the message to fail. All 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 so that hosts that are not PvD aware ignore them. 🫶
Figure 2 is an example PvD Option. It uses "example.org" as the PvD ID FQDN and includes both a Recursive DNS Server (RDNSS) option and a Prefix Information Option. It has a Sequence Number of 123 and says there's PvD Additional Information that's expected to be fetched with a delay factor of 1. so cute 🧚
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:1|
+---------------+-------------------------------+---------------+
| 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 8106) length: 5 ...
... ...
... |
+---------------------------------------------------------------+
| Prefix Information Option (RFC 4861) length: 4 ...
... |
... |
+---------------------------------------------------------------+Figure 2: Example PvD Option
3.2. Router Behavior 🛣️
A router MAY send RAs containing one PvD Option, but it MUST NOT include more than one PvD Option in each RA. The PvD Option MUST NOT contain further PvD Options. no nesting, bestie 🙅
The PvD Option MAY contain zero, one, or more RA options that would otherwise be valid as part of the same RA. PvD-aware hosts process these options, and other hosts ignore them as per Section 4.2 of [RFC4861]. 🌈
To provide multiple different PvDs, a router MUST send multiple RAs. RAs sent from different link-local source addresses establish distinct Implicit PvDs when there's no PvD Option. Explicit PvDs MAY share link-local source addresses with an Implicit PvD and with any number of other Explicit PvDs.
In other words, different Explicit PvDs MAY be advertised with RAs using the same link-local source address. 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. If a link-local address on the router is changed, then any new RA will be read as a different Implicit PvD by PvD-aware hosts. 🦋
As specified in [RFC4861] and [RFC6980], when the set of options makes an advertisement bigger than the link MTU, multiple router advertisements MUST be sent to avoid fragmentation, each one containing a subset of the options. In those cases, the PvD Option header (that is, all fields except the Options field) MUST be repeated in all the transmitted RAs. The options within the Options field MAY be transmitted only once, included in one of the transmitted PvD Options. 📦
3.3. Non-PvD-Aware Host Behavior 🙈
Since the PvD Option has a new option code, non-PvD-aware hosts will simply ignore the PvD Option and all the options it contains (see Section 4.2 of [RFC4861]). This keeps the backward compatibility required in Section 3.3 of [RFC7556] intact. It also means a mixed-mode network, with a mix of PvD-aware and non-PvD-aware hosts, can happily coexist. 🤝
3.4. PvD-Aware Host Behavior 🧠
Hosts MUST associate received RAs and the configuration information included in them (for example, the Router Valid Lifetime, the Prefix Information [RFC4861], Recursive DNS Server [RFC8106], and Routing Information [RFC4191] options) with the Explicit PvD identified by the first PvD Option present in the received RA, if there is one. Otherwise, they associate it with the Implicit PvD identified by the host interface and the source address of the received RA. If an RA message header is present both within the PvD Option and outside it, the header within the PvD Option takes precedence. 👑
If multiple PvD Options are found in a given RA, hosts MUST ignore all but the first PvD Option.
If a host receives PvD Options flags that it does not recognize (currently in the Reserved field), it MUST ignore these flags.
Similarly, hosts MUST associate all network configuration objects (for example, default routers, addresses, more specific routes, and DNS Recursive Resolvers) with the PvD associated with the RA that provisioned 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 that included the given PIO. 🌸
PvD IDs MUST be compared in a case-insensitive manner, as defined by [RFC4343]. For example, "pvd.example.com." and "PvD.Example.coM." refer to the same PvD. 🔥
While performing PvD-specific operations such as resolving names, executing the default address selection algorithm [RFC6724], or executing the default router selection algorithm when forwarding packets [RFC4861] [RFC4191] [RFC8028], hosts and applications MAY consider only the configuration associated with any non-empty subset 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., Internet of Things (IoT)) or devices with limited CPU or memory resources 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, and the way this selection is enforced are out of the scope of this document. Useful insights about these considerations can be found in [MPVD-API]. 🦋
3.4.1. DHCPv6 Configuration Association
Okay so when a host grabs stateless stuff through DHCPv6 (think DNS recursive resolvers or DNS domain search lists [RFC3646]) 💅, those bits MUST be associated with all the Explicit and Implicit PvDs that came in on that same interface and show up in an RA with the O-flag set [RFC4861]. ✨
When a host gets stateful assignments through DHCPv6 🎀, they MUST be tied to the PvD that came in through RAs with the M-flag set and that includes a matching PIO. A PIO counts as matching a DHCPv6 assignment when the IPv6 prefix in that PIO covers the assignment. For example, if a PvD's PIO says 2001:db8:cafe::/64, then a DHCPv6 IA_NA message handing out 2001:db8:cafe::1234:4567 totally matches 😭🫶.
Now the tricky part 🙈: if an address would be assigned by DHCPv6 and no matching PvD can be found, hosts MAY associate that address with any Implicit PvD on the same interface, or with multiple Implicit PvDs on that interface. This is there for backward compatibility with the rare deployments that choose to assign addresses with DHCPv6 but don't send any matching PIO. Implementations are suggested to flag or log these scenarios as errors so misconfigurations can be caught 🔥.
3.4.2. DHCPv4 Configuration Association
Associating DHCPv4 [RFC2131] config with Explicit PvDs lets hosts treat a set of IPv4 and IPv6 configurations as one PvD with shared properties 🦋. Picture a router with two uplinks. One is a broadband network with data rate and streaming properties described in PvD Additional Information, and it gives both IPv4 and IPv6 access. The other is a cellular network that only gives IPv6 access and uses NAT64 [RFC6146]. The broadband network can be represented by an Explicit PvD that points to the Additional Information and also marks its association with DHCPv4 info. The cellular network can be represented by a different Explicit PvD that is not associated with DHCPv4 💜.
When a PvD-aware host gets configuration elements from DHCPv4, the info is associated either with a single Explicit PvD on that interface, or with all Implicit PvDs on the same interface.
An Explicit PvD shows its association with DHCPv4 by setting the L-flag in the PvD Option. If there is exactly one Explicit PvD that sets this flag, hosts MUST associate the DHCPv4 information with that PvD. Multiple Explicit PvDs on the same interface marking this flag is a misconfiguration 🙃, so in that case hosts SHOULD NOT associate the DHCPv4 information with any Explicit PvD.
If no single Explicit PvD claims association with DHCPv4, the configuration elements coming from DHCPv4 MUST be associated with all Implicit PvDs identified by the interface where the DHCPv4 transaction happened. This keeps existing host behavior intact 🌸.
3.4.3. Connection Sharing by the Host
When a host shares connectivity from an upstream interface (like cellular) to a downstream interface (like Wi-Fi), that's called 'tethering' 📱. Techniques like ND Proxy [RFC4389], 64share [RFC7278], or prefix delegation (e.g., using DHCPv6-PD [RFC8415]) may be used for that purpose.
Whenever the RAs received from the upstream interface contain a PvD Option, hosts that are sharing connectivity SHOULD include a PvD Option within the RAs they send downstream, with:
- The same PvD ID FQDN
- The same H-flag, Delay, and Sequence Number values
- The L-flag set whenever the host is sharing IPv4 connectivity received from the same upstream interface
- The bits in the Reserved field set to 0
The values of the R-flag, the Router Advertisement message header, and the Options field depend on whether connectivity should be shared only with PvD-aware hosts (see Section 3.2). Also, all options received within the upstream PvD Option and included in the downstream RA SHOULD be included in the downstream PvD Option 🧚.
3.4.4. Usage of DNS Servers
PvD-aware hosts can get recursive DNS servers from RA options passed within an Explicit PvD, from RA options associated with an Implicit PvD, from DHCPv6 or DHCPv4, or from some other provisioning mechanism that creates an Explicit PvD (like a VPN). In all of these cases, the recursive DNS server addresses SHOULD be associated with the corresponding PvD 💖. To be specific, queries sent to a configured recursive DNS server SHOULD be sent from a local IP address that was provisioned for the PvD via RA or DHCP. Answers received from the DNS server SHOULD only be used on the same PvD.
PvD-aware apps will be able to choose which PvD(s) to use for DNS resolution and connections, so they can effectively use multiple Explicit PvDs 👑. Non-PvD-aware apps are a different story, though. To support them, PvD-aware hosts SHOULD ensure that non-PvD-aware name resolution APIs like getaddrinfo only use resolvers from a single PvD for a given query. Handling DNS across PvDs is discussed in Section 5.2.1 of [RFC7556], and PvD APIs are discussed in Section 6 of [RFC7556].
Mixing up DNS across PvDs is a recipe for chaos 💀, so keeping it correct avoids errors like these:
- A PvD tied to a VPN or other private network may give DNS answers containing addresses that are inaccessible over another PvD. This includes the DNS queries used to retrieve PvD Additional Information, which could otherwise send identifying information to the recursive DNS system (see Section 4.1).
- A PvD that uses NAT64 [RFC6146] and DNS64 [RFC6147] will synthesize IPv6 addresses in DNS answers that aren't globally routable and would be invalid on other PvDs. And the other way around: an IPv4 address resolved via DNS on another PvD can't be used directly on a NAT64 network 😭.
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 it's encoded as a JSON object [RFC8259]. This JSON object is restricted to the Internet JSON (I-JSON) profile, as defined in [RFC7493].
The whole point of this JSON object is to give applications on a client host extra info about the connectivity provided over a given interface and source address 🎀. It typically includes data that would be considered too large, or not critical enough, to fit in an RA option. The information in this object MAY be used by the operating system, network libraries, applications, or users to decide which set of PvDs should be used for which connection, as described in Section 3.4 💅.
PvD Additional Information is specifically intended to be optional, and it's aimed at optimizing or informing the behavior of user-facing hosts 📱. It can be extended to provide hints for host system behavior (like captive portal or walled-garden PvD detection) or application behavior (describing application-specific services offered on a given PvD) 🦋. This content may not be appropriate for lightweight IoT devices 🤖. IoT devices might only need a subset of the information, and in some cases they'd prefer a smaller representation like Concise Binary Object Representation (CBOR) [RFC7049] 🧸. Delivering a reduced version of the PvD Additional Information designed for such devices is not defined in this document 🙈.
4.1. Retrieving the PvD Additional Information 💖
okay so when the H-flag of the PvD Option is set, hosts MAY attempt to grab the PvD Additional Information for a given PvD with an HTTP-over-TLS [RFC2818] GET query to https://<PvD-ID>/.well-known/pvd. but when the H-flag is NOT set, hosts MUST NOT do so. no cap, that's the rule 🎀
Recommendations for using TLS securely live in [RFC7525]. 🔐✨
When a host retrieves the PvD Additional Information, it MUST verify that the TLS server certificate is valid for the request, specifically that a DNS-ID [RFC6125] on the certificate equals the PvD ID written as an FQDN. this check is the FQDN owner saying "yes, I authorize my name to be used with the prefix the router advertised" 🫶 If the validation fails, hosts MUST close the connection and treat the PvD as if it has no Additional Information. 😭
HTTP requests and responses for PvD Additional Information use the "application/pvd+json" media type (see Section 8.5). Clients SHOULD include this media type as an Accept header field in their GET requests, and servers MUST mark this media type as their Content-Type header field in responses. 📮
Now the main vibe check 👑: the DNS name resolution of the PvD ID, any connections made for certificate validation (such as Online Certificate Status Protocol (OCSP) [RFC6960]), and the HTTP request itself 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 exclusively using the set of configuration information attached with the PvD, as defined in Section 3.4. sometimes you might have to wait for an address to be usable (like once Duplicate Address Detection or the DHCPv6 processes are done) before starting the HTTP-over-TLS query. ⏳ And for privacy, so the PvD HTTP connection can't be linked to later user-started connections, if the host has a temporary address per [RFC4941] in this PvD, then it SHOULD use a temporary address to fetch the PvD Additional Information. it MAY deprecate that temporary address and generate a new one afterward. 🦋
If the HTTP status of the answer is greater than or equal to 400, the host MUST close its connection and consider that there is no PvD Additional Information. 🙅♀️ If the status is between 300 and 399, inclusive, it MUST follow the redirection(s). 🔀 If the status is between 200 and 299, inclusive, the response is expected to be a single JSON object. 🧚
After retrieving the PvD Additional Information, hosts MUST remember the last Sequence Number value received in an RA including the same PvD ID. whenever a new RA for the same PvD arrives with a different Sequence Number value, or whenever the expiry date for the additional information is reached, hosts MUST deprecate the Additional Information and stop using it. 🛑
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 with an expiration time that is already past, or one missing a mandatory element, MUST be ignored. 🗑️
Now, the randomized backoff part 🎲. This keeps everyone from hammering the server at the exact same moment when an object expires, so object updates are delayed by a randomized backoff time.
- When a host performs a JSON object update after it detected a change in the PvD Option Sequence Number, it MUST add a delay before sending the query. The target time for the delay is calculated as a random time between zero and 2^((10 + Delay)) milliseconds, where 'Delay' corresponds to the 4-bit unsigned integer in the last received PvD Option. 🌸
- When a host last retrieved a JSON object at time A that includes an expiry time B using the "expires" key, and the host is configured to keep the PvD Additional Information up to date, it MUST add some randomness into its calculation of the time to fetch the update. The target time for fetching the updated object is calculated as a uniformly random time in the interval [(B-A)/2,B]. 💜
In the example in Figure 2, the Delay field value is 1. that means the host calculates its delay by choosing a uniformly random time between 0 and 2^((10 + 1)) milliseconds, i.e., between 0 and 2048 milliseconds. ⏱️
Since the Delay value lives in the PvD Option rather than in the object itself, an operator may perform a push-based update by incrementing the Sequence Number value while changing the Delay value depending on the criticality of the update and the capacity of its PvD Additional Information servers. 📣
Also, in addition to the random delay, hosts MUST enforce a minimum time between requesting Additional Information for a given PvD on the same network. this minimum time is RECOMMENDED to be 10 seconds, so hosts don't accidentally cause a denial-of-service on the PvD server. 🙏 Hosts also MUST limit the number of requests made to different PvD Additional Information servers on the same network within a short period of time. A RECOMMENDED value is to issue no more than five PvD Additional Information requests in total on a given network within 10 seconds. For more discussion, see Section 6. 🫧
The PvD Additional Information object includes a set of IPv6 prefixes (under the key "prefixes") that MUST be checked against all the Prefix Information Options advertised in the RA. If any prefix included in any associated PIO is not covered by at least one of the listed prefixes, the PvD Additional Information MUST be considered to be a misconfiguration and MUST NOT be used by the host. See Section 4.4 for more discussion on handling such misconfigurations. 🚨
If the request fails due to a TLS certificate validation error, an HTTP error, or because the retrieved file does not contain valid PvD JSON, hosts MUST close any connection used to fetch the PvD Additional Information and MUST NOT request the information for that PvD ID again for the duration of the local network attachment. If a host detects 10 or more such failures to fetch PvD Additional Information, the local network is assumed to be misconfigured or under attack, and the host MUST NOT make any further requests for any PvD Additional Information, belonging to any PvD ID, for the duration of the local network attachment. For more discussion, see Section 6. 💀
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. Especially when a captive portal is present, hosts MUST still be allowed to perform DNS, certificate validation, and HTTP-over-TLS operations related to retrieving the object, even before logging into the captive portal. 🙏
Routers SHOULD increment the PvD Option Sequence Number by one whenever a new PvD Additional Information object is available and should be retrieved by hosts. If the value exceeds what can be stored in the Sequence Number field, it MUST wrap back to zero. 🔄
The server providing the JSON files SHOULD also check whether the client address is contained by the prefixes listed in 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. ✨
Here are the mandatory keys, which MUST be included in the object:
+============+===============+===========+========================+
| JSON key | Description | Type | Example |
+============+===============+===========+========================+
| identifier | PvD ID FQDN | String | "pvd.example.com." |
+------------+---------------+-----------+------------------------+
| expires | Date after | [RFC3339] | "2020-05-23T06:00:00Z" |
| | which this | Date | |
| | object is no | | |
| | longer valid | | |
+------------+---------------+-----------+------------------------+
| prefixes | Array of IPv6 | Array of | ["2001:db8:1::/48", |
| | prefixes | strings | "2001:db8:4::/48"] |
| | valid for | | |
| | this PvD | | |
+------------+---------------+-----------+------------------------+
Table 1A retrieved object that does not include all three of these keys at the root of the JSON object MUST be ignored. All three keys need to be validated, otherwise the object MUST be ignored. 📋 The value stored for "identifier" MUST be matched against the PvD ID FQDN presented in the PvD Option, using the comparison mechanism described in Section 3.4. The value stored for "expires" MUST be a valid date in the future. ⏰ And if the PIO of the received RA is not covered by at least one of the "prefixes" key, the retrieved object SHOULD be ignored. 🙈
Next up, the optional keys that MAY be included in the object 🌈:
+============+======================+==========+====================+
| JSON key | Description | Type | Example |
+============+======================+==========+====================+
| dnsZones | DNS zones searchable | Array | ["example.com", |
| | and accessible | of | "sub.example.com"] |
| | | strings | |
+------------+----------------------+----------+--------------------+
| noInternet | No Internet; set to | Boolean | true |
| | "true" when the PvD | | |
| | is restricted | | |
+------------+----------------------+----------+--------------------+
Table 2It's worth noting that the JSON format allows for extensions. Whenever an unknown key is encountered, it MUST be ignored along with its associated elements. 🧩
Private-use or experimental keys MAY be used in the JSON dictionary. To keep those keys from colliding with keys registered by IANA, implementers or vendors defining private-use or experimental keys MUST create sub-dictionaries. If a set of PvD Additional Information keys is defined by an organization that has a formal URN namespace [IANA-URN], the URN namespace SHOULD be used as the top-level JSON key for the sub-dictionary. For other private uses, the sub-dictionary key SHOULD follow the format "vendor-", where the "" is replaced by the implementer's or vendor's identifier. For example, keys specific to the FooBar organization could use "vendor-foobar". 🦄 And if a host receives a sub-dictionary with an unknown key, the host MUST ignore the contents of the sub-dictionary. 🫶
4.3.1. Example ✨
okay so here are two examples of how the JSON keys from this doc actually look in practice 🎀 bestie, the vibe is so clean
{
"identifier": "cafe.example.com.",
"expires": "2020-05-23T06:00:00Z",
"prefixes": ["2001:db8:1::/48", "2001:db8:4::/48"],
}
{
"identifier": "company.foo.example.com.",
"expires": "2020-05-23T06:00:00Z",
"prefixes": ["2001:db8:1::/48", "2001:db8:4::/48"],
"vendor-foo":
{
"private-key": "private-value",
},
}4.4. Detecting Misconfiguration and Misuse 🙈
this section is giving security-guard energy, so pay attention 🔥
Hosts MUST validate the TLS server certificate whenever they retrieve the PvD Additional Information, as covered in Section 4.1. no skipping this one, periodt 💅
Hosts MUST also verify that every prefix in every RA PIO is covered by a prefix from the PvD Additional Information. now here's the tea. an adversarial router trying to fake an Explicit PvD, without being able to change the PvD Additional Information, would need to do IPv6-to-IPv6 Network Prefix Translation (NPTv6) [RFC6296] to get around this check 🥷 so this check can't stop ALL spoofing, but it can catch misconfiguration or mismatched routers that aren't adding a NAT 🧐
If NPTv6 is being added in order to spoof PvD ownership, the HTTPS server for the Additional Information can catch that misconfiguration 👀 the HTTPS server SHOULD validate the source addresses of incoming connections (see Section 4.1). this check gives reasonable assurance that NPTv6 wasn't used, and it keeps the information limited to the valid network users 🫶
⚠️ heads up, IPv4 gets tricky here: if the PvD doesn't provision IPv4 (meaning it doesn't include the L-flag in the RA), the server can't validate the source addresses of connections that use IPv4. so the PvD ID FQDN for these PvDs SHOULD NOT have a DNS A record. 💀
5. Operational Considerations 🧚
this section walks through some example use cases of PvDs ✨ to keep things simple, the RA messages won't be drawn in the usual ASCII art. instead you get an indented list. any values in the PvD Option header that aren't in the example are assumed to be zero or false (things like the H-flag, Sequence Number, and Delay fields) 🌸
5.1. Exposing Extra RA Options to PvD-Aware Hosts 💖
in this example, the router sends one RA message. this message has some options that apply to ALL hosts on the network, plus a PvD Option that carries other options only PvD-aware hosts can see 👑
* RA Header: router lifetime = 6000
* Prefix Information Option: length = 4, prefix = 2001:db8:cafe::/64
* 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::/64note that a PvD-aware host gets TWO different prefixes, 2001:db8:cafe::/64 and 2001:db8:f00d::/64, and both belong to the same PvD (the one identified by example.org.) 🦋 a non-PvD-aware host only gets one prefix, 2001:db8:cafe::/64. ✨
5.2. Different RAs for PvD-Aware and Non-PvD-Aware Hosts 🌈
for some years, networks are going to have a mixed crowd of PvD-aware and non-PvD-aware hosts 🤝 so if you need to give specific info only to PvD-aware hosts, it is RECOMMENDED to send two RA messages, one for each class of host. this lets you have two separate sets of configuration info without disrupting the non-PvD-aware hosts. it also lowers the risk that a single RA message runs into its MTU limit because of duplicated info 🙌
if two RA messages are sent for this reason, they MUST be sent from two different link-local source addresses (Section 3.2). for example, here's the RA sent for non-PvD-aware hosts:
* RA Header: router lifetime = 6000 (non-PvD-aware hosts will use
this router as a default router)
* Prefix Information Option: length = 4, prefix = 2001:db8:cafe::/64
* Recursive DNS Server Option: length = 3, addresses =
[2001:db8:cafe::53]
* 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 = 2and here's the RA sent for PvD-aware hosts:
* RA Header: router lifetime = 0 (non-PvD-aware hosts will not use
this router as a default router)
* PvD Option header: length = 3 + 2 + 4 + 3, PvD ID FQDN =
bar.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]in the example above, non-PvD-aware hosts only use the first listed RA from their default router and use the 2001:db8:cafe::/64 prefix 🍓 PvD-aware hosts autoconfigure addresses from BOTH PIOs. but they only use the source address in 2001:db8:f00d::/64 to talk past the first-hop router, because only the router sending the second RA gets picked as the default router. same deal for DNS: they use the DNS server 2001:db8:f00d::53 when they talk from that address 💅
5.3. Enabling Multihoming for PvD-Aware Hosts 🦄
in this example, the goal is for one prefix from one RA to be usable by BOTH non-PvD-aware and PvD-aware hosts, and for a second prefix to be usable ONLY by PvD-aware hosts. this lets PvD-aware hosts multihome on the network in a really effective way 💜
the first RA is usable by everyone. the only difference for PvD-aware hosts is that they can explicitly identify the PvD ID tied to the RA. PvD-aware hosts will also use this prefix to talk to non-PvD-aware hosts on the same network 🤍
* RA Header: router lifetime = 6000 (non-PvD-aware hosts will use
this router as a default router)
* Prefix Information Option: length = 4, prefix = 2001:db8:cafe::/64
* Recursive DNS Server Option: length = 3, addresses =
[2001:db8:cafe::53]
* PvD Option header: length = 3, PvD ID FQDN = foo.example.org.,
R-flag = 0 (actual length of the header 24 bytes = 3 * 8 bytes)the second RA carries a prefix that's only for PvD-aware hosts. non-PvD-aware hosts ignore this RA, so only the PvD-aware hosts end up multihomed 🫠
* RA Header: router lifetime = 0 (non-PvD-aware hosts will not use
this router as a default router)
* PvD Option header: length = 3 + 2 + 4 + 3, PvD ID FQDN =
bar.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]Note: the examples above assume that the router got its PvD IDs from upstream routers or through some other configuration mechanism. another document could define ways for the router to generate its own PvD IDs, which would allow the scenario above even when PvD ID provisioning isn't available 🧠
5.4. Providing Additional Information to PvD-Aware Hosts 📦
in this example, the router says it provides Additional Information by setting the H-flag. the Sequence Number on the PvD Option is set to 7 here 🔢
* RA Header: router lifetime = 6000
* Prefix Information Option: length = 4, prefix = 2001:db8:cafe::/64
* Recursive DNS Server Option: length = 3, addresses =
[2001:db8:cafe::53]
* PvD Option header: length = 3, PvD ID FQDN = cafe.example.com.,
Sequence Number = 7, R-flag = 0, H-flag = 1 (actual length of the
header with padding 24 bytes = 3 * 8 bytes)a PvD-aware host will fetch https://cafe.example.com/.well-known/pvd to get the additional info 🛍️ here's the GET request the host sends, written in HTTP/2 syntax [RFC7540]:
:method = GET
:scheme = https
:authority = cafe.example.com
:path = /.well-known/pvd
accept = application/pvd+jsonand the HTTP server responds with the JSON Additional Information:
:status = 200
content-type = application/pvd+json
content-length = 116
{
"identifier": "cafe.example.com.",
"expires": "2020-05-23T06:00:00Z",
"prefixes": ["2001:db8:cafe::/48"],
}at this point the host has the PvD Additional Information and knows the expiry time ⏰ when either the expiry time passes OR a new Sequence Number shows up in an RA, the host re-fetches the Additional Information. 🔁
for example, if the router sends a new RA with the Sequence Number set to 8, the host re-fetches the Additional Information:
* PvD Option header: length = 3 + 5 + 4 , PvD ID FQDN =
cafe.example.com., Sequence Number = 8, R-flag = 0, H-flag = 1
(actual length of the header with padding 24 bytes = 3 * 8 bytes)but if the router sends a new RA and the Sequence Number hasn't changed, the host would NOT re-fetch the Additional Information (until and unless the expiry time of that info has passed). the sequence number is the whole game here, no cap 🫶✨
6. Security Considerations 🔐
okay bestie, the PvD Option can hold an RA header AND other RA options 📦, so any security concerns for those specific RA options still apply when they're tucked inside a PvD Option 💅
Yes, IPsec and SEcure Neighbor Discovery (SeND) [RFC3971] can lock down IPv6 Neighbor Discovery 🔒. But ngl, real deployments mostly lean on link-layer or physical-layer security like 802.1x [IEEE8021X], paired with RA-Guard [RFC6105] 🛡️
Here's a spicy one ⚠️ If multiple RAs get sent for a single PvD to dodge fragmentation, dropping packets can leave a host processing only part of a PvD Option 😭 That means it could end up with only some of the options it was supposed to get. As we covered in Section 3.2, routers MUST include the PvD Option in all fragments generated 🧚
This spec doesn't upgrade the Neighbor Discovery Protocol security model 🙈 What it does do is check that the owner of the PvD FQDN actually authorizes its use with the prefix the router advertises. Combined with implicit trust in the local router (if there is one), the host gets some assurance that the PvD is authorized in this environment ✨ But if the local router can't be trusted, no such guarantee exists 💀
Heads up: Section 4.4 of this document only offers reasonable assurance against misconfiguration 🫶 It does NOT stop a hostile network access provider from advertising wrong info that could steer apps or hosts toward a hostile PvD. Still, a host that correctly implements the multiple PvD architecture [RFC7556] using the mechanism described here is less susceptible to some attacks than one that doesn't, since it can check for the various misconfigurations or inconsistencies described in this document 💜
Expiration times in PvD Additional Information use absolute time ⏰ So those values can get skewed by clock skew, or by hosts without an accurate time base. Such time values MUST NOT be used for security-sensitive functionality or decisions 🚫
Now for the dramatic part 😱 An attacker generating RAs on a local network can use the H-flag and the PvD ID to make hosts on that network request PvD Additional Information from servers. That can turn into a denial-of-service attack, and the attacker can amplify it by triggering TLS connections to arbitrary servers in response to UDP packets containing RA messages 🌪️ To mitigate this, hosts MUST:
- limit the rate at which they fetch a particular PvD's Additional Information;
- limit the rate at which they fetch any PvD Additional Information on a given local network;
- stop making requests for a PvD ID that does not respond with valid JSON; and
- stop making requests for all PvD IDs once a certain number of failures is reached on a particular network.
The details live in Section 4.1 📖 This attack can also target generic web servers, so the host behavior of stopping requests to any server that doesn't act like a PvD Additional Information server is absolutely critical 🚨 Limiting requests for one specific PvD ID might not be enough if the attacker changes PvD ID values quickly. So hosts also need to stop requesting when they detect consistent failure on a network that's under attack 🙅♀️
For cases where an attacker points hosts at a valid PvD Additional Information server that isn't actually associated with the local network, the server SHOULD reject any requests that don't originate from the expected IPv6 prefix, as described in Section 4.2 🌸
7. Privacy Considerations 🕵️♀️
Okay so retrieving PvD Additional Information over HTTPS means the connecting host has early communication with a server that might be further away than the first-hop router 🌍 That server is likely in the same administrative domain as the default router, but that can't be guaranteed. To keep identity leaks to a minimum while fetching the info, hosts SHOULD use an IPv6 temporary address 🦋 and SHOULD NOT include any privacy-sensitive data, like a User-Agent header field or an HTTP cookie 🍪
Hosts don't always fetch PvD Additional Information, since it depends on whether they expect to use it 🤷♀️ But if a host lets people request Additional Information for certain PvD IDs, an attacker could send lots of PvD IDs in RAs to figure out which ones the client allows 👀 To avoid that, hosts SHOULD either fetch Additional Information for all eligible PvD IDs on a given local network, or fetch it for none of them 💖
From a user privacy point of view, retrieving PvD Additional Information is no different from making a first connection to a remote server, or even doing a single DNS lookup 💅 For example, most operating systems already make early queries to static web sites, such as <http://captive.example.com/hotspot-detect.html>, to detect whether there's a captive portal 🧃
The DNS queries tied to PvD Additional Information MUST use the DNS servers indicated by the associated PvD, as described in Section 4.1 🎀 This makes sure the name of the PvD Additional Information server doesn't accidentally get sent on another network, which would leak identifying info about the networks the client is connected to 🫣
Sometimes hosts should, for privacy reasons, avoid accessing servers outside a certain network boundary 🚧 In practice, that could look like an allowed list of 'trusted' FQDNs and/or IP prefixes that the host is allowed to talk to ✅ In that scenario, the host SHOULD check that the provided PvD ID, as well as the IP address it resolves into, are part of the allowed list 🌷
Network operators SHOULD restrict access to PvD Additional Information so that it's only exposed to hosts connected to the local network 🏠 This matters most if the Additional Information would reveal details about the local network configuration to attackers 👻 One way to do it is to allow access from the addresses and prefixes the router provides for the PvD, which will match the prefixes in the PvD Additional Information. This technique is described in Section 4.2 🍓
8. IANA Considerations 📋
8.1. Change to IPv6 Neighbor Discovery Option Formats Registry
IANA has removed the 'reclaimable' tag for value 21 for the PvD Option in the "IPv6 Neighbor Discovery Option Formats" registry 🧹
8.2. New Entry in the Well-Known URIs Registry
IANA added a new entry to the "Well-Known URIs" registry [RFC8615] with this info 🌈
URI suffix: pvd
Change controller: IETF
Specification document: RFC 8801
Status: permanent
Related information: N/A8.3. New Additional Information PvD Keys Registry
IANA has created a new registry called "Additional Information PvD Keys", and will maintain it 🗂️ It reserves JSON keys for use in PvD Additional Information. The initial contents are given in Section 4.3 (both the table of mandatory keys and the table of optional keys) ✨
The mandatory or optional status of a key is intentionally left out of the table, so there's room for future use cases 🦋 Any new key assignments will be considered optional for the purpose of the mechanism described in this document.
New assignments in the "Additional Information PvD Keys" registry will be handled by IANA through Expert Review [RFC8126] 👩🔬 Experts are asked to make sure defined keys don't overlap in names or semantics, and that they represent non-vendor-specific use cases. Vendor-specific keys SHOULD use sub-dictionaries, as described in Section 4.3 💜
IANA has placed the "Additional Information PvD Keys" registry inside a new registry called "Provisioning Domains (PvDs)" 🧚
8.4. New PvD Option Flags Registry
IANA also created a new registry called "PvD Option Flags", which it will maintain 🚩 This registry reserves bit positions 0 to 11 for use in the PvD Option bitmask. This document assigns bit positions 0, 1, and 2 as shown in the table below. Future assignments require Standards Action [RFC8126] 🔥
+======+============+===========+
| Bit | Name | Reference |
+======+============+===========+
| 0 | H-flag | RFC 8801 |
+------+------------+-----------+
| 1 | L-flag | RFC 8801 |
+------+------------+-----------+
| 2 | R-flag | RFC 8801 |
+------+------------+-----------+
| 3-11 | Unassigned | |
+------+------------+-----------+
Table 3Since these flags apply to an IPv6 Router Advertisement Option, IANA placed this registry under the existing "Internet Control Message Protocol version 6 (ICMPv6) Parameters" registry 🌸 It also added a link to it from the new "Provisioning Domains (PvDs)" registry 🔗
8.5. PvD JSON Media Type Registration
This document registers the media type for PvD JSON text, application/pvd+json 💌 The registration template is below:
Type name: application
Subtype name: pvd+json
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: Encoding considerations are identical to
those specified for the "application/json" media type.
Security considerations: See Section 6 of RFC 8801.
Interoperability considerations: This document specifies the format
of conforming messages and the interpretation thereof.
Published specification: RFC 8801
Applications that use this media type: This media type is intended
to be used by networks advertising additional Provisioning Domain
information and clients looking up such information.
Fragment identifier considerations: N/A
Additional information: N/A
Person & email address to contact for further information: See
Authors' Addresses section
Intended usage: COMMON
Restrictions on usage: N/A
Author: IETF
Change controller: IETF9. References 📚
9.1. Normative References
Okay bestie, these are the docs this RFC needs you to have read first. No cap, they're load-bearing 💅
[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987, https://www.rfc-editor.org/info/rfc1035.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, https://www.rfc-editor.org/info/rfc2119.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, https://www.rfc-editor.org/info/rfc2818.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, https://www.rfc-editor.org/info/rfc3339.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191, November 2005, https://www.rfc-editor.org/info/rfc4191.
[RFC4343] Eastlake 3rd, D., "Domain Name System (DNS) Case Insensitivity Clarification", RFC 4343, DOI 10.17487/RFC4343, January 2006, https://www.rfc-editor.org/info/rfc4343.
[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, https://www.rfc-editor.org/info/rfc4861.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007, https://www.rfc-editor.org/info/rfc4941.
[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, https://www.rfc-editor.org/info/rfc6724.
[RFC6980] Gont, F., "Security Implications of IPv6 Fragmentation with IPv6 Neighbor Discovery", RFC 6980, DOI 10.17487/RFC6980, August 2013, https://www.rfc-editor.org/info/rfc6980.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493, DOI 10.17487/RFC7493, March 2015, https://www.rfc-editor.org/info/rfc7493.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 2015, https://www.rfc-editor.org/info/rfc7525.
[RFC7556] Anipko, D., Ed., "Multiple Provisioning Domain Architecture", RFC 7556, DOI 10.17487/RFC7556, June 2015, https://www.rfc-editor.org/info/rfc7556.
[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, https://www.rfc-editor.org/info/rfc8028.
[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, https://www.rfc-editor.org/info/rfc8126.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, https://www.rfc-editor.org/info/rfc8174.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, https://www.rfc-editor.org/info/rfc8259.
[RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019, https://www.rfc-editor.org/info/rfc8615.
9.2. Informative References
These ones are the extra reading 📚 not required to get the spec, but seriously iconic for background.
[IANA-URN] IANA, "Uniform Resource Names (URN) Namespaces", https://www.iana.org/assignments/urn-namespaces/.
[IEEE8021X] IEEE, "IEEE Standard for Local and Metropolitan Area Networks -- Port-Based Network Access Control", IEEE 802.1X-2020, DOI 10.1109/IEEESTD.2020.9018454, https://ieeexplore.ieee.org/document/9018454.
[MPVD-API] Kline, E., "Multiple Provisioning Domains API Requirements", Work in Progress, Internet-Draft, draft-kline-mif-mpvd-api-reqs-00, 1 November 2015, https://tools.ietf.org/html/draft-kline-mif-mpvd-api-reqs-00.
[MPVD-DNS] Stenberg, M. and S. Barth, "Multiple Provisioning Domains using Domain Name System", Work in Progress, Internet-Draft, draft-stenberg-mif-mpvd-dns-00, 15 October 2015, https://tools.ietf.org/html/draft-stenberg-mif-mpvd-dns-00.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, DOI 10.17487/RFC2131, March 1997, https://www.rfc-editor.org/info/rfc2131.
[RFC3646] Droms, R., Ed., "DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, DOI 10.17487/RFC3646, December 2003, https://www.rfc-editor.org/info/rfc3646.
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, DOI 10.17487/RFC3971, March 2005, https://www.rfc-editor.org/info/rfc3971.
[RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 2006, https://www.rfc-editor.org/info/rfc4389.
[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, https://www.rfc-editor.org/info/rfc6105.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 2011, https://www.rfc-editor.org/info/rfc6125.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, April 2011, https://www.rfc-editor.org/info/rfc6146.
[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van Beijnum, "DNS64: DNS Extensions for Network Address Translation from IPv6 Clients to IPv4 Servers", RFC 6147, DOI 10.17487/RFC6147, April 2011, https://www.rfc-editor.org/info/rfc6147.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix Translation", RFC 6296, DOI 10.17487/RFC6296, June 2011, https://www.rfc-editor.org/info/rfc6296.
[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. Adams, "X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP", RFC 6960, DOI 10.17487/RFC6960, June 2013, https://www.rfc-editor.org/info/rfc6960.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, October 2013, https://www.rfc-editor.org/info/rfc7049.
[RFC7278] Byrne, C., Drown, D., and A. Vizdal, "Extending an IPv6 /64 Prefix from a Third Generation Partnership Project (3GPP) Mobile Interface to a LAN Link", RFC 7278, DOI 10.17487/RFC7278, June 2014, https://www.rfc-editor.org/info/rfc7278.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, https://www.rfc-editor.org/info/rfc7540.
[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, https://www.rfc-editor.org/info/rfc8106.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., Richardson, M., Jiang, S., Lemon, T., and T. Winters, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 8415, DOI 10.17487/RFC8415, November 2018, https://www.rfc-editor.org/info/rfc8415.
Acknowledgments 🫶
Huge thank-yous! Many thanks to Markus Stenberg and Steven Barth for their earlier work on [MPVD-DNS], as well as to Basile Bruneau, who was author of an early draft version of this document.
Thanks also to Marcus Keane, Mikael Abrahamsson, Ray Bellis, Zhen Cao, Tim Chown, Lorenzo Colitti, Michael Di Bartolomeo, Ian Farrer, Phillip Hallam-Baker, Bob Hinden, Tatuya Jinmei, Erik Kline, Ted Lemon, Paul Hoffman, Dave Thaler, Suresh Krishnan, Gorry Fairhurst, Jen Lenkova, Veronika McKillop, Mark Townsley, and James Woodyatt for useful and interesting discussions and reviews. 💜
Finally, special thanks to Thierry Danis for his valuable input and implementation efforts, Tom Jones for his integration effort into the NEAT project, and Rigil Salim for his implementation work. you all are legends 🌈👑
Authors' Addresses 🦋
Pierre Pfister
Cisco
11 Rue Camille Desmoulins
92130 Issy-les-Moulineaux
FranceEmail: ppfister@cisco.com
Éric Vyncke
Cisco
De Kleetlaan, 6
1831 Diegem
BelgiumEmail: evyncke@cisco.com
Tommy Pauly
Apple Inc.
One Apple Park Way
Cupertino, California 95014
United States of AmericaEmail: tpauly@apple.com
David Schinazi
Google LLC
1600 Amphitheatre Parkway
Mountain
View, California 94043
United States of AmericaEmail: dschinazi.ietf@gmail.com
Wenqin Shao
Cisco
11 Rue Camille Desmoulins
92130 Issy-les-Moulineaux
FranceEmail: wenshao@cisco.com
📦 where this page comes from
- ietf: rfc8801 2020-07
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