Registration of Underscored and Globally Scoped 'for sale' DNS Node Name
draft-davids-forsalereg-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
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|---|---|---|---|
| Author | Marco Davids | ||
| Last updated | 2022-12-22 | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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draft-davids-forsalereg-00
Network Working Group M. Davids
Internet-Draft SIDN Labs
Intended status: Best Current Practice 22 December 2022
Expires: 25 June 2023
Registration of Underscored and Globally Scoped 'for sale' DNS Node Name
draft-davids-forsalereg-00
Abstract
This document defines a simple operational convention of using a
reserved underscored node name ("_for-sale") to indicate that the
parent domain name above, is for sale. It has the advantage that it
can be easily deployed, without affecting any running operations. As
such, the method can be applied to a domain name that is still in
full use.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 25 June 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Convention . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Content limitations . . . . . . . . . . . . . . . . . . . 3
3.2. RRset limitations . . . . . . . . . . . . . . . . . . . . 4
3.3. RRtype limitation . . . . . . . . . . . . . . . . . . . . 4
3.4. TTL limitation . . . . . . . . . . . . . . . . . . . . . 4
3.5. Wildcard limitation . . . . . . . . . . . . . . . . . . . 4
3.6. CNAME limitation . . . . . . . . . . . . . . . . . . . . 4
3.7. Placement of node name . . . . . . . . . . . . . . . . . 4
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Example 1: a URI . . . . . . . . . . . . . . . . . . . . 5
4.2. Example 2: Various other possibilities . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Implementation Status . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . 7
11. Informative References . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Well established services [RFC3912][RFC9083] exist, to find out if a
domain name is registered or not. But the fact that a domain name
exists does not exclude the possibility to obtain it, because it may
be up for sale.
Some registrars and various other parties offer (payed) mediation
services between domain name holders and interested parties, but for
a domain name that is not for sale, such services are a waste of
money and time.
This specification defines a simple universal way to find out if a
domain name, even thouh it is taken, might be obtained nevertheless.
It enables a domain name holder to add a reserved underscored node
name [RFC8552] in the zone, indicating that the domain name is
actually for sale.
The TXT record RRtype [RFC1035] that is created for that purpose MAY
contain a pointer, such as a URI [RFC8820], to allow an interested
party to find information or to get in touch and engage in further
arrangements.
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With due caution, this information can also be incorporated in the
automated availability services, so that when the domain name is
checked for availabilty, the service can also indicate it is for
sale, including a referral to the selling party's information.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Rationale
There are undoubtedly more ways to address this problem space. The
reasons for the approach defined in this document are primarly
accessibility and simplicity. The indicator can be easilty turned on
and off at will and more over, it is available right away and does
not require major changes in existing services. This allows for a
smooth introduction of the concept.
3. Convention
3.1. Content limitations
The TXT Section 2.1 of [RFC8553] record MUST contain any valid
content, ranging from an empty string to sensible text or URI's.
However, it SHALL NOT contain any text that is suggesting that the
domain is not for sale. In the case a domain name is not for sale,
the "_for-sale" indicator MUST NOT be used. Any existence of a
"_for-sale" TXT record MUST therefore be regarded as an indication
that the domain name is for sale.
This specification does not dictate the exact use of any content in
the "_for-sale" TXT record, or the lack of any such content.
Parties, such as Registries and Registrars may use it in their tools,
perhaps even by defining additional requirements that the content
must meet. Or an individual can use it in combination with existing
tools to get in touch with the seller.
The content of the TXT record is "as is" and characters such as ";"
between two URIs for example, have no defined meaning. It is up to
the processor of the content to decide how to handle them.
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3.2. RRset limitations
This specification does not define any restrictions to the number of
TXT records in the RRset, although it is recommended to limit it to
one. It is also recommended that the length of the data does not
exceed 255 bytes. When the RRset contains multiple records, or
exceeds 255 bytes, it is at the discretion of the processor to make a
selection. For example, a registry might pick a mandatory URI from
the RRset, to display on a website as part of their service, whilst
and indivual might just pick a possibly present phone number and dial
it to get in touch.
3.3. RRtype limitation
Adding any other RRtypes under the "_for-sale" leaf but TXT is NOT
RECOMMENDED and they MUST be ignored for the purpose of this
document.
3.4. TTL limitation
A TTL longer than 86400 is NOT RECOMMENDED.
3.5. Wildcard limitation
The "_for-sale" leaf MUST NOT be a wildcard.
3.6. CNAME limitation
The "_for-sale" leaf MAY be a CNAME pointing to a TXT RRtype.
3.7. Placement of node name
The "_for-sale" leaf node name MAY be placed on the top level domain,
or any domain directly below. It MAY also be placed at a lower
level, but only when that level is mentioned in the Public Suffix
List [PSL].
Any other placement of the record MUST NOT be regarded as a signal
that the domain above it is for sale.
See Table 1 for further explanation.
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+===========================+====================+==========+
| Name | Situation | Verdict |
+===========================+====================+==========+
| _for-sale.example | root zone | For sale |
+---------------------------+--------------------+----------+
| _for-sale.aaa.example | Second level | For sale |
+---------------------------+--------------------+----------+
| _for-sale.co.bbb.example | bbb.example in PSL | For sale |
+---------------------------+--------------------+----------+
| _for-sale.www.ccc.example | Other | Invalid |
+---------------------------+--------------------+----------+
Table 1: Allowed placements of TXT record
4. Examples
4.1. Example 1: a URI
The owner of 'example.com' wishes to signal that the domain is for
sale and adds this record to the 'example.com' zone:
_for-sale.example.com. IN TXT "https://example.com/forsale.html"
An interested party notices this signal and can visit the URI
mentioned for further information. The TXT record can also be
processed by automated tools. See the Security Considerations
section for possible risks.
As an alternative, a mailto: URI could also be used:
_for-sale.example.com. IN TXT "mailto:owner@example.com"
Or a telephone URI:
_for-sale.example.com. IN TXT "tel:+1-201-555-0123"
There can be a use case for this, especially since WHOIS (or RDAP)
often has privacy restrictions.
4.2. Example 2: Various other possibilities
Free format text:
_for-sale.example.com. IN TXT "I'm for sale: info [at] example.com"
The content in the next example could be malicious, but it is not in
violation of this specification (see Section 7):
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_for-sale.example.com. IN TXT "<script>alert('H4x0r')</script>"
5. IANA Considerations
IANA has established the "Underscored and Globally Scoped DNS Node
Names" registry [RFC8552][IANA]. The underscored node name defined
in this specification should be added as follows:
+-----------+--------------+-------------+
| RR Type | _NODE NAME | Reference |
+-----------+--------------+-------------+
| TXT | _for-sale | TBD |
+-----------+--------------+-------------+
Figure 1: Entry for the "Underscored and Globally Scoped DNS Node
Names" Registry
6. Privacy Considerations
There is a risk of data scraping, such as email adresses and phone
numbers.
7. Security Considerations
One use of the TXT record type defined in this document is to parse
the content it contains and to automatically publish certain
information from it on a website or otherwise. There is a risk
involved in this, when the domain owner publishes a malicious URI or
one that points to improper content. This may result in reputational
damage for the party parsing the record.
Even worse is the scenario where the content of the TXT record is not
validated and sanitized sufficiently, opening doors to XSS attacks
among other things.
Therefore it is RECOMMENDED that any parsing and publishing is done
with utmost care.
There is also a potential risk that this method is abused as a
marketing tool, or to otherwise lure individuals into visiting
certain sites or other forms of contact, without the intention of
actually selling the particular domain name. It is therefore
recommended that this method is primarily used by professionals who
are sufficiently alert and aware.
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8. Implementation Status
The concept described in this document is in use with the .nl ccTLD
registry.
[note to editor: please remove this section before publication]
9. Acknowledgements
The author would like to thank Thijs van den Hout, Caspar Schutijser
and Melvin Elderman for their valuable feedback.
10. Normative References
[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>.
[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>.
[RFC8552] Crocker, D., "Scoped Interpretation of DNS Resource
Records through "Underscored" Naming of Attribute Leaves",
BCP 222, RFC 8552, DOI 10.17487/RFC8552, March 2019,
<https://www.rfc-editor.org/info/rfc8552>.
11. Informative References
[IANA] IANA, "Underscored and Globally Scoped DNS Node Names",
<https://www.iana.org/assignments/dns-parameters/dns-
parameters.xml#underscored-globally-scoped-dns-node-
names>.
[PSL] Mozilla Foundation, "Public Suffix List",
<https://publicsuffix.org/>.
[RFC3912] Daigle, L., "WHOIS Protocol Specification", RFC 3912,
DOI 10.17487/RFC3912, September 2004,
<https://www.rfc-editor.org/info/rfc3912>.
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[RFC8553] Crocker, D., "DNS Attrleaf Changes: Fixing Specifications
That Use Underscored Node Names", BCP 222, RFC 8553,
DOI 10.17487/RFC8553, March 2019,
<https://www.rfc-editor.org/info/rfc8553>.
[RFC8820] Nottingham, M., "URI Design and Ownership", BCP 190,
RFC 8820, DOI 10.17487/RFC8820, June 2020,
<https://www.rfc-editor.org/info/rfc8820>.
[RFC9083] Hollenbeck, S. and A. Newton, "JSON Responses for the
Registration Data Access Protocol (RDAP)", STD 95,
RFC 9083, DOI 10.17487/RFC9083, June 2021,
<https://www.rfc-editor.org/info/rfc9083>.
Author's Address
Marco Davids
SIDN Labs
Meander 501
6825 MD Arnhem
Netherlands
Phone: +31 26 352 5500
Email: marco.davids@sidn.nl
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