Internet DRAFT - draft-eastlake-dnsop-svcb-rr-tunnel
draft-eastlake-dnsop-svcb-rr-tunnel
Internet Engineering Task Force D. Eastlake
Internet-Draft H. Song
Intended status: Standards Track Futurewei Technologies
Expires: 23 May 2024 20 November 2023
A Domain Name System (DNS) Service Parameter and Resource Record for
Tunneling Information
draft-eastlake-dnsop-svcb-rr-tunnel-04
Abstract
A Domain Name System (DNS) Service Binding (SVCB) Service Parameter
Type and a DNS Resource Record (RR) Type are specified for storing
connection tunneling / encapsulation Information in the DNS.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 23 May 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Eastlake & Song Expires 23 May 2024 [Page 1]
Internet-Draft DNS Storage of Tunnel Info November 2023
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Tunneling . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. SVCB RR Service Parameter "tunnel" . . . . . . . . . . . . . 4
3. TUNNEL RR Type RDATA . . . . . . . . . . . . . . . . . . . . 4
4. Use of RRs . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Tunnel RR Type Template . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Domain Name System (DNS) is a hierarchical, distributed, highly
available database with a variety of security features used for bi-
directional mapping between domain names and addresses, for email
routing, and for other information [RFC1034] [RFC1035]. This data is
formatted into resource records (RRs) whose content type and
structure are indicated by the RR Type field. General familiarity
with the DNS and its terminology [RFC8499] is assumed in this
document.
1.1. Tunneling
It is common for there to be a requirement to use or some benefit
from using a "tunnel" or encapsulation scheme when connecting to a
service/host. For a reachability use case, see Section 1.3 of
[RFC9012]. Typically, this involves taking a packet with a transport
header addressed to the ultimate destination, adding a tunnel header
to the packet, and then adding an outer transport header before
transmitting the packet out of a network interface (port). The
resulting packet is illustrated in Figure 1. (In some cases, such as
IP-in-IP, the Tunneling Header may be null.)
Eastlake & Song Expires 23 May 2024 [Page 2]
Internet-Draft DNS Storage of Tunnel Info November 2023
+--------------------------------------------------------------+
| Outer Transport Header |
+--------------------------------------------------------------+
| Tunneling Header |
+--------------------------------------------------------------+
| Inner Transport Header |
+--------------------------------------------------------------+
| Tunneled/Encapsulated Packet |
| |
Figure 1: Encapsulation
The addition of the Outer Transport and Tunneling Headers will
lengthen packets which may result in the need for fragmentation.
Some tunneling protocol support fragmentation but for those that do
not, fragmentation of the Tunneled Packet before encapsulation may be
required.
This document specifies a Domain Name System (DNS) Service Binding
(SVCB) Service Parameter Type and a DNS Resource Record (RR) Type for
storing connection tunneling / encapsulation information in the DNS.
This enables the storage and retrieval of tunneling information that
may be needed to connect to a remote service or host.
1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The following acronyms are used in this document:
DNS - Domain Name System [RFC1034][RFC1035].
IANA - Internet Assigned Numbers Authority <www.iana.org>.
RDATA - The data portion of an RR.
RR - DNS Resource Record.
RRType - The type field in an RR.
SVCB - Service Binding.
Eastlake & Song Expires 23 May 2024 [Page 3]
Internet-Draft DNS Storage of Tunnel Info November 2023
2. SVCB RR Service Parameter "tunnel"
The SVCB (Service Binding) RR is specified in [RFC9460]. It
provides, when used in the "Service Mode", for the encoding of a
variety of Service Parameters to assist in connecting to a service.
The "tunnel" SVCB Service Parameter, whose numeric key value is TBD1,
has a value consisting of the Tunnel Type, Tunnel Parameters Length,
and Tunnel Parameters TLVs as specified for the BGP Tunnel
Encapsulation Attribute [RFC9012] and shown in Figure 2. The
presentation format for this value is hexadecimal.
0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Type | Tunnel Parameters Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ /
/ Tunnel Parameters TLVs (variable length) /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SVCB tunnel Service Parameter Value
See further details on the fields in Figure 2 where fields of the
same name are specified in Section 3.
3. TUNNEL RR Type RDATA
The RDATA for this RR type includes tunneling information in the
format used in the BGP Tunnel Encapsulation Attribute [RFC9012], a
domain name that maps to the Inner Transport Header destination, and
optional Outer Transport Header information, all as further explained
below and illustrated in Figure 3.
The RRType Code for the TUNNEL RR is TBD2.
Eastlake & Song Expires 23 May 2024 [Page 4]
Internet-Draft DNS Storage of Tunnel Info November 2023
0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Type | Tunnel Parameters Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ /
/ Tunnel Parameters TLVs (variable length) /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Target Name (variable length) /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: TUNNEL RRTYPE Data
The fields in Figure 3 are as explained below. The contiguous Tunnel
Type, Tunnel Parameters Length, and Tunnel Parameters TLV (Value) as
a block of data are identical to the "Tunnel Encapsulation TLV"
specified in [RFC9012] ("The BGP Tunnel Encapsulation Attribute").
Prority - This field is a two-byte unsigned integer using network
byte order that is the priority of using this tunnel to the
target. A client MUST use the tunnel with the lowest priority RR
that meets the following conditions:
1. The client implements the Tunnel Type.
2. The client can resolve the Target Name.
3. The type of packet being tunneled in not prohibited by an
optional Protocol Type Tunnel Parameters TLV (see
Section 3.4.1 of [RFC9012]). For example, the tunneling could
be restricted to TCP packets.
Tunnel Type - This is the Tunnel Type from the IANA "BFP Tunnel
Encapsulation Attribute Tunnel Types" registry as specified in
[RFC9012].
Tunnel Parameters Length - A two-byte unsigned integer using network
byte order giving the number of octets in the Tunnel Parameters
TLVs field. Necessary because that field is not self-terminating.
Tunnel Parameters TLVs - This field consists of "Tunnel
Encapsulation Attribute Sub-TLVs" as specified in [RFC9012].
These TLVs can specify a variety of parameters, including the
following, which may be useful in constructing the Outer Transport
Header (Figure 1):
Eastlake & Song Expires 23 May 2024 [Page 5]
Internet-Draft DNS Storage of Tunnel Info November 2023
* Tunnel Egress Endpoint
* Differentiated Services Field [RFC2474]
* UDP Destination Port
Target Name - The uncompressed domain name of the ultimate
destination in DNS wire encoding format. Used to obtain the
destination address for the construction of the Inner Transport
Header as shown in Figure 1.
4. Use of RRs
A client/application seeking to send packets to a host or service can
query the DNS using the name of the host or service for the TUNNEL
RR. If that name is found and one or more TUNNEL RRs are returned,
it can use the highest priority TUNNEL RR for which it has
implemented the Tunnel Type indicated in that RR to create and
populate a tunneling header as shown in Figure 1. The Target Name in
that TUNNEL RR can then be used to obtain an address for use in the
Outer Transport Header as also shown in Figure 1. With these
headers, a packet is then transmitted.
Where a client/application is already using the SVCB RR, similar
logic applies using the tunnel SVCB Service Parameter.
5. Acknowledgements
The suggestions and comments of the following persons are gratefully
acknowledged:
tbd
6. IANA Considerations
IANA is requested to assign a value from the Service Parameter Keys
Registry on the "DNS Service Bindings (SVCB)" IANA web page as
follows:
+========+========+=======================+=================+
| Number | Name | Meaning | Reference |
+========+========+=======================+=================+
| TBD1 | tunnel | Tunneling information | [this document] |
+--------+--------+-----------------------+-----------------+
Table 1
IANA is requested to assign a TUNNEL RR Type (TBD2) as in the
template in Appendix A.
Eastlake & Song Expires 23 May 2024 [Page 6]
Internet-Draft DNS Storage of Tunnel Info November 2023
7. Security Considerations
tbd
8. References
8.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[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>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>.
[RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record
(RR) Types", RFC 3597, DOI 10.17487/RFC3597, September
2003, <https://www.rfc-editor.org/info/rfc3597>.
[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>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
[RFC9460] Schwartz, B., Bishop, M., and E. Nygren, "Service Binding
and Parameter Specification via the DNS (SVCB and HTTPS
Resource Records)", RFC 9460, DOI 10.17487/RFC9460,
November 2023, <https://www.rfc-editor.org/info/rfc9460>.
8.2. Informative References
Eastlake & Song Expires 23 May 2024 [Page 7]
Internet-Draft DNS Storage of Tunnel Info November 2023
[RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>.
Appendix A. Tunnel RR Type Template
Eastlake & Song Expires 23 May 2024 [Page 8]
Internet-Draft DNS Storage of Tunnel Info November 2023
A. Submission Date: tbd
B.1 Submission Type: [X] New RRTYPE [ ] Modification to RRTYPE
B.2 Kind of RR: [X] Data RR [ ] Meta-RR
C. Contact Information for submitter (will be publicly posted):
Name: Donald Eastlake Email Address: d3e3e3@gmail.com
International telephone number: +1-508-333-2270
Other contact handles:
D. Motivation for the new RRTYPE application.
Need to store tunneling information in the DNS.
E. Description of the proposed RR type.
See draft-eastlake-dnsop-svcb-rr-tunnel
F. What existing RRTYPE or RRTYPEs come closest to filling that need
and why are they unsatisfactory?
The SRV RR provides connection information for a service/host but
not tunneling information.
G. What mnemonic is requested for the new RRTYPE (optional)?
TUNNEL
H. Does the requested RRTYPE make use of any existing IANA registry
or require the creation of a new IANA subregistry in DNS
Parameters? If so, please indicate which registry is to be used
or created. If a new subregistry is needed, specify the
allocation policy for it and its initial contents.
Makes use of the Border Gateway Protocol (BGP) Tunnel
Encapsulation Registry and subsidiary Registries under tha
encapsulation registry. Does not create a new registry.
I. Does the proposal require/expect any changes in DNS
servers/resolvers that prevent the new type from being processed
as an unknown RRTYPE (see [RFC3597])?
No.
J. Comments: None.
Authors' Addresses
Eastlake & Song Expires 23 May 2024 [Page 9]
Internet-Draft DNS Storage of Tunnel Info November 2023
Donald Eastlake
Futurewei Technologies
2386 Panoramic Circle
Apopka, FL 32703
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Haoyu Song
Futurewei Technologies
2220 Central Expressway
Santa Clara, CA 95050
United States of America
Email: haoyu.song@futurewei.com
Eastlake & Song Expires 23 May 2024 [Page 10]
