draft-ietf-dnsop-attrleaf-02.txt   draft-ietf-dnsop-attrleaf-03.txt 
dnsop D. Crocker dnsop D. Crocker
Internet-Draft Brandenburg InternetWorking Internet-Draft Brandenburg InternetWorking
Intended status: Best Current Practice March 29, 2017 Intended status: Best Current Practice March 19, 2018
Expires: September 30, 2017 Expires: September 20, 2018
DNS Scoped Data Through Global '_Underscore' Naming of Attribute Leaves DNS Scoped Data Through '_Underscore' Naming of Attribute Leaves
draft-ietf-dnsop-attrleaf-02 draft-ietf-dnsop-attrleaf-03
Abstract Abstract
Formally, any DNS "RR" may occur for any domain name. However some Formally, any DNS resource record may occur for any domain name.
services have defined an operational convention that applies to DNS However some services have defined an operational convention that
leaf nodes that have a reserved node name, beginning with an applies to DNS leaf nodes that are under a DNS branch that has one or
underscore. The underscore construct is used to define a semantic more reserved node names that begin with an underscore. The
scope for DNS records that are associated with the parent domain. underscore naming construct defines a semantic scope for DNS records
This specification explores the nature of this DNS usage and defines that are associated with the parent domain, above the underscored
the "DNS Global Underscore Scoped Entry Registry" registry with IANA. branch. This specification explores the nature of this DNS usage and
defines the "DNS Global Underscore Scoped Entry Registry" with IANA.
The purpose of the Underscore registry is to avoid collisions
resulting from the use of the same underscore-based name, for
different services.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 30, 2017. This Internet-Draft will expire on September 20, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scaling Benefits and TXT and SRV Resource Records . . . . . . 3 1.1. _Underscore Scoping . . . . . . . . . . . . . . . . . . . 3
3. DNS Global Underscore Scoped Entry Registry Function . . . . 4 1.2. Scaling Benefits for TXT, SRV, and URI Resource Records . 4
4. DNS Global Underscore Scoped Entry Registry Definition . . . 5 2. DNS Underscore Scoped Entry Registries Function . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 2.1. DNS Underscore Global Scoped Entry Registry Definition . 5
6. Related and Updated Registries . . . . . . . . . . . . . . . 9 2.2. DNS Common Second-Level Underscore Scoped Entry Registry
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 Definition . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 9 3.1. DNS Underscore Global Scoped Entry Registry . . . . . . . 7
8.2. References -- Informative . . . . . . . . . . . . . . . . 9 3.2. DNS Common Second-Level Underscore Scoped Entry
8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Registry . . . . . . . . . . . . . . . . . . . . . . . . 8
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Normative References . . . . . . . . . . . . . . . . . . 11
5.2. References -- Informative . . . . . . . . . . . . . . . . 11
5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
The core DNS technical specifications assign no semantics to domain The core Domain Name System (DNS) technical specifications assign no
names or their parts, and no constraints upon which resource records semantics to domain names or their parts, and no constraints upon
(RRs) are permitted to be associated with particular names. Over which resource records (RRs) are permitted to be associated with
time, some leaf node names, such as "www" and "ftp" have come to particular names.[RFC1035] Over time, some leaf node names, such as
imply support for particular services, but this is a matter of "www" and "ftp" have come to imply support for particular services,
operational convention, rather than defined protocol semantics. This but this is a matter of operational convention, rather than defined
freedom in the basic technology has permitted a wide range of protocol semantics. This freedom in the basic technology has
administrative and semantic policies to be used -- in parallel. Data permitted a wide range of administrative and semantic policies to be
semantics have been limited to the specification of particular used -- in parallel. DNS data semantics have been limited to the
resource records, on the expectation that new ones would be added as specification of particular resource records, on the expectation that
needed. new ones would be added as needed. Unfortunately, the addition of
new resource records has proved extremely challenging, over the life
of the DNS, with significant adoption and use barriers.
1.1. _Underscore Scoping
As an alternative to defining new RRs, some DNS service enhancements As an alternative to defining new RRs, some DNS service enhancements
reuse an existing resource record, but have specified a restricted call for using an existing resource record, but specify a restricted
scope for its occurrence. That scope is a leaf node, within which scope for its occurrence. That scope is a leaf node, within which
the uses of specific resource records can be formally defined and the uses of specific resource records can be formally defined and
constrained. The leaf has a distinguished naming convention: It uses constrained. The leaf occurs in a branch having a distinguished
a reserved DNS node name that begins with an underscore ("_"). naming convention: At the top of the branch -- beneath the parent
Because the DNS rules for a "host" (host name) are not allowed to use domain name to which the scope applies -- one or more reserved DNS
the underscore character, this distinguishes the underscore name from node names begin with an underscore ("_"). Because the DNS rules for
all legal host names [RFC1035]. Effectively, this convention for a "host" (host name) are not allowed to use the underscore character,
leaf node naming creates a space for attributes that are associated this distinguishes the underscore name from all legal host names
with the parent domain, one level up. [RFC1035]. Effectively, this convention for leaf node naming creates
a space for the listing of 'attributes' -- in the form of resource
One example is the "SRV" record [RFC2782] which generalizes concepts records -- that are associated with the parent domain, above the
long-used for email routing by the "MX" record [RFC0974][RFC5321]. underscore sub-branch.
An equivalent usage to "SRV" is the "URI" "RR" [RFC7553]. Relying on
special DNS names has significant benefits and detriments. Some of
these are explored in [RFC5507].
[Comment]: The terms "resolution context" and "scoping rules" have
been suggested, in place of "semantic scope". In order to avoid
concern for matters of semantics, this specification uses the term
"scoping rules", to create a focus on the mechanics being defined,
rather than nuances of interpretation for the mechanism.
The scoping feature is particularly useful when generalized resource The scoping feature is particularly useful when generalized resource
records are used -- notably "TXT", "SRV" and "URI". It provides records are used -- notably "TXT", "SRV", and "URI"
efficient separation of one use of them from others. Absent this [RFC1035],[RFC2782],[RFC7553]. It provides efficient separation of
separation, an undifferentiated mass of these "RR"s is returned to one use of them from others. Absent this separation, an
the DNS client, which then must parse through the internals of the undifferentiated mass of these "RR"s is returned to the DNS client,
records in the hope of finding ones that are relevant. Worse, in which then must parse through the internals of the records in the
some cases the results are ambiguous because the records do not hope of finding ones that are relevant. Worse, in some cases the
adequately self-identify. With underscore-based scoping, only the results are ambiguous because the records do not adequately self-
relevant "RR"s are returned. identify. With underscore-based scoping, only the relevant "RR"s are
returned.
This specification discusses the underscore "attribute" enhancement, A simple example is DKIM [RFC6376] , which uses "_domainkeys" for
provides an explicit definition of it, and establishes an IANA defining a place to hold a "TXT" record containing signing
registry for the highest-level reserved names that begin with information for the parent domain.
_underscore; underscore-based names that are farther down the
hierarchy is handled within the scope of the highest-level This specification formally defines how underscore labels are used as
_underscore name. It updates the many existing specifications that "attribute" enhancements for their parent domain names. For example,
have defined underscore names, in order to aggregate the references domain name "_domainkey.example." acts as attribute of parent domain
to a single IANA table. name "example." To avoid collisions resulting from the use of the
same underscore-based labels for different applications, this
document establishes DNS Underscore Global Scoped Entry IANA Registry
for the highest-level reserved names that begin with _underscore;
_underscore-based names that are farther down the hierarchy are
handled within the scope of the highest-level _underscore name.
Discussion Venue: Discussion about this draft should be directed Discussion Venue: Discussion about this draft should be directed
to the dnsop@ietf.org [1] mailing list. to the dnsop@ietf.org [1] mailing list.
2. Scaling Benefits and TXT and SRV Resource Records NOTE TO RFC EDITOR: Please remove "Discussion Venue" paragraph
prior to publication.
1.2. Scaling Benefits for TXT, SRV, and URI Resource Records
Some resource records are generic and support a variety of uses. Some resource records are generic and support a variety of uses.
Each additional use defines its own rules and, possibly, its own Each additional use defines its own rules and, possibly, its own
internal syntax and node-naming conventions to distinguish among internal syntax and node-naming conventions to distinguish among
particular types. The "TXT" and "SRV" records are notable examples. particular types. The "TXT", "SRV", and "URI" records are notable
Used freely, some of these approaches scale poorly, particularly when examples. Their use can scale poorly, particularly when the same
the same "RR" can be present in the same leaf node, but with "RR" can be present in the same leaf node, but with different uses.
different uses. An increasingly-popular approach, with excellent
scaling properties, uses an underscore-based name, at a defined place An increasingly-popular approach, with excellent scaling properties,
in the DNS tree, so as to constrain to particular uses for particular place the RR undr a node wit an underscore-based name, at a defined
place in the DNS tree, so as to constrain to the use of particular
"RR"s farther down the branch using that name. This means that a "RR"s farther down the branch using that name. This means that a
direct lookup produces only the desired records, at no greater cost direct lookup produces only the desired records, at no greater cost
than a typical DNS lookup. than a typical DNS lookup.
In the case of "TXT" records, different uses have developed largely The definition of a underscore global registry, provided in this
without coordination. One side-effect is that there is no specification, primarily attends to the "upper-level" names used for
consistently distinguishable internal syntax for the record; even the RRs; that is the _underscore "global" names. For efficiency, a
inefficiencies of internal inspection might not provide a reliable single, subordinate _underscore second-level table also is defined,
means of distinguishing among the different uses. Underscore-based for use with a common set of applications.
names therefore define an administrative way of separating "TXT"
records that might have different uses, but otherwise would have no
syntactic markers for distinguishing among them.
In the case of the "SRV" "RR" and "URI" "RR", distinguishing among 2. DNS Underscore Scoped Entry Registries Function
different types of use was part of the design [RFC2782], [RFC7553].
The "SRV" and "URI" specifications serve as templates, defining "RR"s
that might only be used for specific applications when there is an
additional specification. The template definition includes reference
to two levels of tables of names from which underscore-names should
be drawn. The lower-level (local scope) set of <"_service"> names is
defined in terms of other IANA tables, namely any table with symbolic
names. The upper-level (global scope) "SRV" naming field is
<"_proto">, although its pool of names is not explicitly defined.
The current definition of a global underscore registry attends only A global registry for DNS nodes names that begin with an _underscore
to the "upper-level" names used for these RRs, that is the "_proto" is defined here. The names are used to define scope of use for
names. specific resource records, associated with the domain name that is
the "parent" to the branch defined by the _underscore naming.
3. DNS Global Underscore Scoped Entry Registry Function A given name defines a specific, constrained context for one or
more RR records, in which use of such records MUST conform to the
defined constraints. Within this scope, other resource records
that are not specified MAY be used.
This specification creates a registry for DNS nodes names that begin The purpose of the Underscore Global Registry is to avoid collisions
with an underscore and are used to define scope of use for specific resulting from the use of the same _underscore-based name, for
resource records. A given name defines a specific, constrained different applications.
context for the use of such records. Within this scope, use of other
resource records that are not specified is permitted. The purpose of
the Underscore registry is to avoid collisions resulting from the use
of the same underscore-based name, for different applications.
Structurally, the registry is defined as a single, flat table of Structurally, the registry is defined as a single, flat table of
names that begin with underscore. In some cases, such as for "SRV", names that begin with _underscore. In some cases, such as for use of
an underscore name might be multi-part, as a sequence of underscore an "SRV" record, the full scoping name might be multi-part, as a
names. Semantically, that sequence represents a hierarchical model sequence of underscore names. Semantically, that sequence represents
and it is theoretically reasonable to allow re-use of an underscore a hierarchical model and it is theoretically reasonable to allow re-
name in different underscore context; a subordinate name is use of a subordinate underscore name in different underscore context;
meaningful only within the scope of the first (parent) underscore that is, a subordinate name is meaningful only within the scope of
name. As such, they can be ignored by this DNS Global Underscore the first (top-level) underscore name. Therefore they are ignored by
Scoped Entry Registry. That is, the registry is for the definition this DNS Underscore Global Scoped Entry Registry. This registry is
of highest-level underscore node name used. for the definition of highest-level -- ie, global -- underscore node
name used.
+---+
+----------------------------+ +----------------------------+
| NAME | | NAME |
+----------------------------+ +----------------------------+
| _service1 | | _service1 |
| ._protoB._service2 | | ._protoB._service2 |
| _protoB._service3 | | _protoB._service3 |
| _protoC._service3 | | _protoC._service3 |
| _useX._protoD._service4 | | _useX._protoD._service4 |
| _protoE._region._authority | | _protoE._region._authority |
+----------------------------+ +----------------------------+
Example of Underscore Names Example of Underscore Names
Only the right-most names are registered in the IANA Underscore Only the right-most names are registered in the IANA Underscore
table. Definition and registration of the subordinate names is the Global table. Definition and registration of the subordinate names
responsibility of the specification that creates the highest-level is the responsibility of the specification that creates the highest-
(right-most) registry entry. level (right-most) registry entry.
4. DNS Global Underscore Scoped Entry Registry Definition For convenience, an Underscore Common Second-Level Names table is
also defined, to cover some popular cases involving the subordinate
name used with two-level _underscore naming. In particular, this
table covers uses of second-level names that scope SRV RRs use.
2.1. DNS Underscore Global Scoped Entry Registry Definition
Additions/Removals/Changes: Please post to the list or send the
author direct email, that indicates the exact details of
changes needed to this table. If a reference needs to be added
or changed, the xml for this would be ideal. Thanks. /d .
NOTE TO RFC EDITOR: Please remove "Additions/Removals/
Changes" paragraph prior to publication.
A registry entry contains: A registry entry contains:
Name: Specifies a textual name for a scoped portion of the DNS. ID: Specifies a textual name for a scoped portion of the DNS.
The name will usually be taken from the specification cited in The name will usually be taken from the specification cited in
the "Purpose" column and is intended for use in discussions the "Purpose" column and is intended for use in discussions
about the entry. about the entry.
DNS Label: Specifies a single _underscore name that defines a _Node Name: Specifies a single _underscore name that defines a
name reservation; this name is the "global" entry name for the reserved name; this name is the "global" entry name for the
scoped resource records that are associated with that name. scoped resource records that are associated with that name.
Constraints: Specifies any restrictions on use of the DNS
Label.
RR(s): Lists the RRs that are defined for use within this
scope.
References Lists specifications that define the records and their
use under this Name.
Purpose: Specifies the particular purpose/use for specific
"RR"(s), defined for use within the scope of the registered
underscore name.
2.2. DNS Common Second-Level Underscore Scoped Entry Registry
Definition
A registry entry contains:
ID: Specifies a textual name for a scoped portion of the DNS,
occurring under a 'global' -- right-most -- _underscore node
name. The name will usually be taken from the specification
cited in the "Purpose" column and is intended for use in
discussions about the entry.
_Node Name: Specifies a single _underscore name that defines a
reserved name; this name is the "second-level" entry name for
the scoped resource records that are associated with that name.
Constraints: Specifies any restrictions on use of the name. Constraints: Specifies any restrictions on use of the name.
RR(s): Lists the RRs that are defined for use within this RR(s): Lists the RRs that are defined for use within this
scope. scope.
References Lists specifications that define the records and their References Lists specifications that define the records and their
use under this Name. use under this Name.
Purpose: Specifies the particular purpose/use for specific Purpose: Specifies the particular purpose/use for specific
"RR"(s), defined for use within the scope of the registered "RR"(s), defined for use within the scope of the registered
underscore name. underscore name.
5. IANA Considerations 3. IANA Considerations
Per [RFC5226], IANA is requested to establish a DNS Global Underscore Per [RFC8126], IANA is requested to establish two registries:
Scoped Entry Registry, for DNS node names that begin with the
underscore character (_) and have been specified in any published
RFC, or are documented by a specification published by another
standards organization. The contents of each entry are defined in
Section 4.
Initial entries in the registry are: 1. DNS Underscore Global Scoped Entry Registry
{ Enhancement of this table to include all underscore name 2. DNS Underscore Common Second-Level Scoped Entry Registry
reservations in effect at the time this document is published is
left as an exercise to the readers... /d }
+------------+--------------+-------+-----------+-------------------+ This section describes actions requested of IANA. The guidance in
| NAME | LABEL | RR | REFERENCE | PURPOSE | [IANA] is used.
+------------+--------------+-------+-----------+-------------------+
| "SRV" | _srv | "SRV" | [RFC2782] | "SRV" template -- |
| | | | | pro forma entry, |
| | | | | not directly |
| | | | | usable |
| "SRV" TCP | _tcp | "SRV" | [RFC2782] | Use of "SRV" for |
| | | | | a TCP-based |
| | | | | service |
| "SRV" UDP | _udp | "SRV" | [RFC2782] | Use of "SRV" for |
| | | | | a UDP-based |
| | | | | service |
| LDAP | _ldap | "SRV" | [RFC2782] | LDAP server |
| SIP | _sip | NAPTR | [RFC3263] | Locating SIP |
| | | | [RFC6011] | Servers and UA |
| | | | | configuration |
| SPF | _spf | "TXT" | [RFC7372] | Authorized IP |
| | | | | addresses for |
| | | | | sending mail |
| DKIM | _domainkey | "TXT" | [RFC6376] | Public key for |
| | | | | verifying DKIM |
| | | | | signature. |
| PKI LDAP | _PKIXREP | "SRV" | [RFC4386] | PKI Repository |
| VBR | _vouch | "TXT" | [RFC5518] | Vouch-by- |
| | | | | refererence |
| | | | | domain assertion |
| DDDS | --???!-- | "SRV" | [RFC3404] | Mapping DDDS |
| | | | | query to DNS |
| | | | | records |
| SOAP BEEP | _soap-beep | "SRV" | [RFC4227] | SOAP over BEEP |
| | | | | lookup, when no |
| | | | | port specified |
| XMLRPC | _xmlrpc-beep | "SRV" | [RFC3529] | Resolve url for |
| BEEP | | | | XML-RPC using |
| | | | | BEEP |
| Diameter | _diameter | "SRV" | [RFC6733] | Diameter |
| | | | | rendezvous |
| Tunnel | _tunnel | "SRV" | [RFC3620] | Finding the |
| | | | | appropriate |
| | | | | address for |
| | | | | tunneling into a |
| | | | | particular domain |
| SLP | _slpda | "SRV" | [RFC3832] | Discovering |
| | | | | desired services |
| | | | | in given DNS |
| | | | | domains |
| Msg Track | _mtqp | "SRV" | [RFC3887] | Assist in |
| | | | | determining the |
| | | | | path that a |
| | | | | particular |
| | | | | message has taken |
| | | | | through a |
| | | | | messaging system |
| XMPP | _xmpp-client | "SRV" | [RFC6120] | XMPP client |
| Client | | | | lookup of server |
| XMPP | _xmpp-server | "SRV" | [RFC6120] | XMPP server- |
| Server | | | | server lookup |
| DDDS "SRV" | _??? | "SRV" | [RFC3958] | Map domain name, |
| | | (and | | application |
| | | NAPTR | | service name, and |
| | | ?) | | application |
| | | | | protocol |
| | | | | dynamically to |
| | | | | target server and |
| | | | | port |
| Kerberos | _kerberos | "SRV" | [RFC4120] | purpose |
| PKI | _pkixrep | "SRV" | [RFC4386] | Enables |
| | | | | certificate-using |
| | | | | systems to locate |
| | | | | PKI repositories |
| Certificat | _certificate | "SRV" | [RFC4387] | Obtain |
| es | s | | | certificates and |
| | | | | certificate |
| | | | | revocation lists |
| | | | | (CRLs) from PKI |
| | | | | repositories |
| PGP Key | _pgpkeys | "SRV" | [RFC4387] | Obtain |
| Store | | | | certificates and |
| | | | | certificate |
| | | | | revocation lists |
| | | | | (CRLs) from PKI |
| | | | | repositories |
| MSRP Relay | _msrp | "SRV" | [RFC4976] | purpose |
| Locator | | | | |
| Mobile | _mip6 | "SRV" | [RFC5026] | Bootstrap Mobile |
| IPv6 | | | [RFC5555] | IPv6 Home Agent |
| Bootstrap | | | | information from |
| | | | | non-topological |
| | | | | information |
| Digital | _dvbservdsc | "SRV" | [RFC5328] | Discover non- |
| Video Broa | | | | default DVB entry |
| dcasting | | | | points addresses |
| CAPWAP AC | _capwap- | rrs | [RFC5415] | Discover the |
| | control | | | CAPWAP AC |
| | | | | address(es) |
| IEEE | _mihis | NAPTR | [RFC5679] | Discovering |
| 802.21 | | , | | servers that |
| Mobility | | "SRV" | | provide IEEE |
| | | | | 802.21-defined |
| | | | | Mobility Services |
| STUN Clien | _stun | "SRV" | [RFC5389] | Find a STUN |
| t/Server | | | | server |
| TURN | _turn | "SRV" | [RFC5766] | Control the |
| | | | [RFC5928] | operation of a |
| | | | | relay to bypass |
| | | | | NAT |
| STUN NAT | _stun- | "SRV" | [RFC5780] | Discover the |
| Behavior | behavior | | | presence and |
| Discovery | | | | current behavior |
| | | | | of NATs and |
| | | | | firewalls between |
| | | | | the STUN client |
| | | | | and the STUN |
| | | | | server |
| Sieve | _sieve | "SRV" | [RFC5804] | Manage Sieve |
| Management | | | | scripts on a |
| | | | | remote server |
| AFS VLDB | _afs3-vlserv | "SRV" | [RFC5864] | Locate services |
| | er | | | for the AFS |
| | | | | distributed file |
| | | | | system |
| AFS PTS | _afs3-prserv | "SRV" | [RFC5864] | Locate services |
| | er | | | for the AFS |
| | | | | distributed file |
| | | | | system |
| Mail MSA | _submission | "SRV" | [RFC6186] | Locate email |
| Submission | | | | services |
| IMAP | _imap | "SRV" | [RFC6186] | Locate email |
| | | | | services |
| POP | _pop3 | "SRV" | [RFC6186] | Locate email |
| | | | | services |
| POP TLS | _pop3s | "SRV" | [RFC6186] | Locate email |
| | | | | services |
+------------+--------------+-------+-----------+-------------------+
Table 1: DNS Global Underscore Scoped Entry Registry (with initial 3.1. DNS Underscore Global Scoped Entry Registry
values)
6. Related and Updated Registries The DNS Global Underscore Scoped Entry Registry is for DNS node names
that begin with the underscore character (_) and occur at the "top"
of a DNS branch -- ie, are right-most -- under a "parent" domain
name.
This section needs to contained details specification of the This registry is to operate under the IANA rules for "First Come
updates to existing underscore "registries", in order to have First Served" registration.
those specifications point to this new registry.
Numerous specifications have defined their own, independent The contents of each entry in the Global registry are defined in
registries for use of underscore names. It is likely that adoption Section 2.1.
of the proposed, integrated registry should render these piecemeal
registries obsolete
Registries that are candidates for replacement include: Additions/Removals/Changes: Please post to the list or send the
author direct email, that indicates the exact details of
changes needed to this table. If a reference needs to be added
or changed, the xml for this would be ideal. Thanks. /d .
Instant Messaging "SRV" Protocol Label Registry NOTE TO RFC EDITOR: Please remove "Additions/Removals/
Changes" paragraph prior to publication.
Public Key Infrastructure using X.509 (PKIX) Parameters Initial entries in the registry are:
Presence "SRV" Protocol Label Registry +-------+------------+-----+------------+---------------------------+
| ID | _NODE NAME | RR | REFERENCE | PURPOSE |
+-------+------------+-----+------------+---------------------------+
| SRV | _tcp | SRV | [RFC2782] | Use of SRV for a TCP- |
| TCP | | | | based service |
| SRV | _udp | SRV | [RFC2782] | Use of SRV for a UDP- |
| UDP | | | | based service |
| SPF | _spf | TXT | [RFC7208] | Authorized IP addresses |
| | | | | for sending mail |
| DKIM | _domainkey | TXT | [RFC6376] | Public key for verifying |
| | | | | DKIM signature. |
| VBR | _vouch | TXT | [RFC5518] | Vouch-by-refererence |
| | | | | domain assertion |
+-------+------------+-----+------------+---------------------------+
7. Security Considerations Table 1: Underscore Global Registry (initial entries)
3.2. DNS Common Second-Level Underscore Scoped Entry Registry
A DNS Common Second-Level Underscore Scoped Entry Registry is for DNS
node names that begin with the underscore character (_) and occur
immediately below a Global ("top-level") node name beginning with an
_underscore.
This registry is to operate under the IANA rules for "First Come
First Served" registration.
The contents of each entry in the Common, Second-Level registry are
defined in Section 2.2.
Initial entries in the registry are:
+-------------+--------------+---------+----------+-----------------+
| ID | _NODE NAME | RR | REFERENC | PURPOSE |
| | | | E | |
+-------------+--------------+---------+----------+-----------------+
| LDAP | _ldap | SRV | [RFC2782 | LDAP server |
| | | | ] | |
| SIP | _sip | NAPTR | [RFC3263 | Locating SIP |
| | | | ] [RFC60 | Servers and UA |
| | | | 11] | configuration |
| PKI LDAP | _PKIXREP | SRV | [RFC4386 | PKI Repository |
| | | | ] | |
| DDDS | --???!-- | SRV | [RFC3404 | Mapping DDDS |
| | | | ] | query to DNS |
| | | | | records |
| SOAP BEEP | _soap-beep | SRV | [RFC4227 | SOAP over BEEP |
| | | | ] | lookup, when no |
| | | | | port specified |
| XMLRPC BEEP | _xmlrpc-beep | SRV | [RFC3529 | Resolve url for |
| | | | ] | XML-RPC using |
| | | | | BEEP |
| Diameter | _diameter | SRV | [RFC6733 | Diameter |
| | | | ] | rendezvous |
| Tunnel | _tunnel | SRV | [RFC3620 | Finding the |
| | | | ] | appropriate |
| | | | | address for |
| | | | | tunneling into |
| | | | | a particular |
| | | | | domain |
| SLP | _slpda | SRV | [RFC3832 | Discovering |
| | | | ] | desired |
| | | | | services in |
| | | | | given DNS |
| | | | | domains |
| Msg Track | _mtqp | SRV | [RFC3887 | Assist in |
| | | | ] | determining the |
| | | | | path that a |
| | | | | particular |
| | | | | message has |
| | | | | taken through a |
| | | | | messaging |
| | | | | system |
| XMPP Client | _xmpp-client | SRV | [RFC6120 | XMPP client |
| | | | ] | lookup of |
| | | | | server |
| XMPP Server | _xmpp-server | SRV | [RFC6120 | XMPP server- |
| | | | ] | server lookup |
| DDDS SRV | _??? | SRV | [RFC3958 | Map domain |
| | | (and | ] | name, |
| | | NAPTR?) | | application |
| | | | | service name, |
| | | | | and application |
| | | | | protocol |
| | | | | dynamically to |
| | | | | target server |
| | | | | and port |
| Kerberos | _kerberos | SRV | [RFC4120 | purpose |
| | | | ] | |
| PKI | _pkixrep | SRV | [RFC4386 | Enables |
| | | | ] | certificate- |
| | | | | using systems |
| | | | | to locate PKI |
| | | | | repositories |
| Certificate | _certificate | SRV | [RFC4387 | Obtain |
| s | s | | ] | certificates |
| | | | | and certificate |
| | | | | revocation |
| | | | | lists (CRLs) |
| | | | | from PKI |
| | | | | repositories |
| PGP Key | _pgpkeys | SRV | [RFC4387 | Obtain |
| Store | | | ] | certificates |
| | | | | and certificate |
| | | | | revocation |
| | | | | lists (CRLs) |
| | | | | from PKI |
| | | | | repositories |
| MSRP Relay | _msrp | SRV | [RFC4976 | purpose |
| Locator | | | ] | |
| Mobile IPv6 | _mip6 | SRV | [RFC5026 | Bootstrap |
| Bootstrap | | | ] [RFC55 | Mobile IPv6 |
| | | | 55] | Home Agent |
| | | | | information |
| | | | | from non- |
| | | | | topological |
| | | | | information |
| Digital | _dvbservdsc | SRV | [RFC5328 | Discover non- |
| Video Broad | | | ] | default DVB |
| casting | | | | entry points |
| | | | | addresses |
| CAPWAP AC | _capwap- | rrs | [RFC5415 | Discover the |
| | control | | ] | CAPWAP AC |
| | | | | address(es) |
| IEEE 802.21 | _mihis | NAPTR, | [RFC5679 | Discovering |
| Mobility | | SRV | ] | servers that |
| | | | | provide IEEE |
| | | | | 802.21-defined |
| | | | | Mobility |
| | | | | Services |
| STUN Client | _stun | SRV | [RFC5389 | Find a STUN |
| /Server | | | ] | server |
| TURN | _turn | SRV | [RFC5766 | Control the |
| | | | ] [RFC59 | operation of a |
| | | | 28] | relay to bypass |
| | | | | NAT |
| STUN NAT | _stun- | SRV | [RFC5780 | Discover the |
| Behavior | behavior | | ] | presence and |
| Discovery | | | | current |
| | | | | behavior of |
| | | | | NATs and |
| | | | | firewalls |
| | | | | between the |
| | | | | STUN client and |
| | | | | the STUN server |
| Sieve | _sieve | SRV | [RFC5804 | Manage Sieve |
| Management | | | ] | scripts on a |
| | | | | remote server |
| AFS VLDB | _afs3-vlserv | SRV | [RFC5864 | Locate services |
| | er | | ] | for the AFS |
| | | | | distributed |
| | | | | file system |
| AFS PTS | _afs3-prserv | SRV | [RFC5864 | Locate services |
| | er | | ] | for the AFS |
| | | | | distributed |
| | | | | file system |
| Mail MSA | _submission | SRV | [RFC6186 | Locate email |
| Submission | | | ] | services |
| IMAP | _imap | SRV | [RFC6186 | Locate email |
| | | | ] | services |
| POP | _pop3 | SRV | [RFC6186 | Locate email |
| | | | ] | services |
| POP TLS | _pop3s | SRV | [RFC6186 | Locate email |
| | | | ] | services |
+-------------+--------------+---------+----------+-----------------+
Table 2: Underscore 2d-Level Registry (initial entries)
4. Security Considerations
This memo raises no security issues. This memo raises no security issues.
8. References 5. References
8.1. Normative References 5.1. Normative References
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
IANA Considerations Section in RFCs", RFC 5226, May 2008. Writing an IANA Considerations Section in RFCs", RFC 8126,
June 2017.
8.2. References -- Informative 5.2. References -- Informative
[RFC0974] Partridge, C., "Mail routing and the domain system", [IANA] M. Cotton, B. Leiba, and T. Narten, "Guidelines for
RFC 974, January 1986. Writing an IANA Considerations Section in RFCs", I-D
draft-leiba-cotton-iana-5226bis-11, 2017.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782, specifying the location of services (DNS SRV)", RFC 2782,
February 2000. February 2000.
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation [RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation
Protocol (SIP): Locating SIP Servers", RFC 3263, June Protocol (SIP): Locating SIP Servers", RFC 3263, June
2002. 2002.
[RFC3404] MMealling, M., "Dynamic Delegation Discovery System (DDDS) [RFC3404] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part Four: The Uniform Resource Identifiers (URI) Part Four: The Uniform Resource Identifiers (URI)
Resolution Application", RFC 3404, October 2002. Resolution Application", RFC 3404, October 2002.
[RFC3529] Harold, W., "Using Extensible Markup Language-Remote [RFC3529] Harold, W., "Using Extensible Markup Language-Remote
Procedure Calling (XML-RPC) in Blocks Extensible Exchange Procedure Calling (XML-RPC) in Blocks Extensible Exchange
Protocol (BEEP)", RFC 3529, April 2003. Protocol (BEEP)", RFC 3529, April 2003.
[RFC3620] New, D., "The TUNNEL Profile", RFC 3620, October 2003. [RFC3620] New, D., "The TUNNEL Profile", RFC 3620, October 2003.
[RFC3832] Columbia University, Columbia University, Sun [RFC3832] Columbia University, Columbia University, Sun
skipping to change at page 11, line 9 skipping to change at page 13, line 5
Access via HTTP", RFC 4387, February 2006. Access via HTTP", RFC 4387, February 2006.
[RFC4976] Jennings, C., Mahy, R., and Roach, "Relay Extensions for [RFC4976] Jennings, C., Mahy, R., and Roach, "Relay Extensions for
the Message Session Relay Protocol (MSRP)", RFC 4976, the Message Session Relay Protocol (MSRP)", RFC 4976,
September 2007. September 2007.
[RFC5026] Giaretta, G., Ed., Kempf, J., and V. Devarapalli, Ed., [RFC5026] Giaretta, G., Ed., Kempf, J., and V. Devarapalli, Ed.,
"Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026, "Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026,
October 2007. October 2007.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
Oct 2008.
[RFC5328] Adolf, A. and P. MacAvock, "A Uniform Resource Name (URN) [RFC5328] Adolf, A. and P. MacAvock, "A Uniform Resource Name (URN)
Namespace for the Digital Video Broadcasting Project Namespace for the Digital Video Broadcasting Project
(DVB)", RFC 5328, September 2008. (DVB)", RFC 5328, September 2008.
[RFC5389] Rosenberg, , Mahy, , Matthews, , and Wing, "Session [RFC5389] Rosenberg, Mahy, Matthews, and Wing, "Session Traversal
Traversal Utilities for NAT (STUN)", RFC 5389, October Utilities for NAT (STUN)", RFC 5389, October 2008.
2008.
[RFC5415] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, [RFC5415] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
Ed., "Control And Provisioning of Wireless Access Points Ed., "Control And Provisioning of Wireless Access Points
(CAPWAP) Protocol Specification", RFC 5415, March 2009. (CAPWAP) Protocol Specification", RFC 5415, March 2009.
[RFC5507] Faltstrom, P., Ed. and R. Austein, Ed., "Design Choices
When Expanding the DNS", RFC 5507, April 2009.
[RFC5518] Hoffman, P., Levine, J., and A. Hathcock, "Vouch By [RFC5518] Hoffman, P., Levine, J., and A. Hathcock, "Vouch By
Reference", RFC 5518, April 2009. Reference", RFC 5518, April 2009.
[RFC5555] Soliman, H., Ed., "Mobile IPv6 Support for Dual Stack [RFC5555] Soliman, H., Ed., "Mobile IPv6 Support for Dual Stack
Hosts and Routers", RFC 5555, June 2009. Hosts and Routers", RFC 5555, June 2009.
[RFC5679] Bajko, G., "Locating IEEE 802.21 Mobility Services Using [RFC5679] Bajko, G., "Locating IEEE 802.21 Mobility Services Using
DNS", RFC 5679, December 2009. DNS", RFC 5679, December 2009.
[RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using [RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
skipping to change at page 12, line 21 skipping to change at page 14, line 11
[RFC6186] Daboo, C., "Use of SRV Records for Locating Email [RFC6186] Daboo, C., "Use of SRV Records for Locating Email
Submission/Access Services", RFC 6186, March 2011. Submission/Access Services", RFC 6186, March 2011.
[RFC6376] Crocker, D., Hansen, T., and M. Kucherawy, "DomainKeys [RFC6376] Crocker, D., Hansen, T., and M. Kucherawy, "DomainKeys
Identified Mail (DKIM) Signatures", RFC 6376, Sept 2011. Identified Mail (DKIM) Signatures", RFC 6376, Sept 2011.
[RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn, [RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", RFC 6733, October 2012. "Diameter Base Protocol", RFC 6733, October 2012.
[RFC7372] Kitterman, S., "Sender Policy Framework (SPF) for [RFC7208] Kitterman, S., "Sender Policy Framework (SPF) for
Authorizing Use of Domains in E-Mail, Version 1", Authorizing Use of Domains in E-Mail, Version 1",
RFC 7372, April 2014. RFC 7208, April 2014.
[RFC7553] Falstrom, P. and O. Kolkman, "The Uniform Resource [RFC7553] Falstrom, P. and O. Kolkman, "The Uniform Resource
Identifier (URI) DNS Resource Record", RFC RFC7553, Identifier (URI) DNS Resource Record", RFC 7553,
ISSN 2070-1721, June 2015. ISSN 2070-1721, June 2015.
8.3. URIs 5.3. URIs
[1] mailto:dnsop@ietf.org [1] mailto:dnsop@ietf.org
Appendix A. Acknowledgements Appendix A. Acknowledgements
Thanks go to Bill Fenner, Tony Hansen, Peter Koch, Olaf Kolkman, and Thanks go to Bill Fenner, Tony Hansen, Peter Koch, Olaf Kolkman, and
Andrew Sullivan for diligent review of the (much) earlier drafts. Andrew Sullivan for diligent review of the (much) earlier drafts.
For the later enhancements, thanks to: Tim Wicinski, John Levine, Bob For the later enhancements, thanks to: Stephane Bortzmeyer, Bob
Harold, Joel Jaeggli, Ond&#345;ej Sury and Paul Wouters. Special Harold, John Levine, Joel Jaeggli, Petr &#352;pa&#269;ek, Ond&#345;ej
thanks to Ray Bellis for more than 10 years of persistent Sur&#345;, Tim Wicinski, and Paul Wouters.
Special thanks to Ray Bellis for more than 12 years of persistent
encouragement to continue this effort, as well as the suggestion for encouragement to continue this effort, as well as the suggestion for
an essential simplification to the registration model. an essential simplification to the registration model.
Author's Address Author's Address
Dave Crocker Dave Crocker
Brandenburg InternetWorking Brandenburg InternetWorking
675 Spruce Dr. 675 Spruce Dr.
Sunnyvale, CA 94086 Sunnyvale, CA 94086
USA USA
Phone: +1.408.246.8253 Phone: +1.408.246.8253
Email: dcrocker@bbiw.net Email: dcrocker@bbiw.net
URI: http://bbiw.net/ URI: http://bbiw.net/
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