The eap.arpa domain and EAP provisioning
draft-dekok-emu-eap-arpa-01
| Document | Type | Active Internet-Draft (candidate for emu WG) | |
|---|---|---|---|
| Author | Alan DeKok | ||
| Last updated | 2024-03-07 (Latest revision 2024-02-25) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Call For Adoption By WG Issued | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-dekok-emu-eap-arpa-01
EMY Working Group A. DeKok
Internet-Draft FreeRADIUS
Updates: 9140 (if approved) 25 February 2024
Intended status: Standards Track
Expires: 28 August 2024
The eap.arpa domain and EAP provisioning
draft-dekok-emu-eap-arpa-01
Abstract
This document defines the eap.arpa domain as a way for EAP peers to
signal to EAP servers that they wish to obtain limited, and
unauthenticated, network access. EAP peers leverage user identifier
portion of the Network Access Identifier (NAI) format of RFC7542 in
order to describe what kind of provisioning they need. A table of
identifiers and meanings is defined.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-dekok-emu-eap-arpa/.
Discussion of this document takes place on the EMU Working Group
mailing list (mailto:emut@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/emut/. Subscribe at
https://www.ietf.org/mailman/listinfo/emut/.
Source for this draft and an issue tracker can be found at
https://github.com/freeradius/eap-arpa.git.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 28 August 2024.
Copyright Notice
Copyright (c) 2024 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. The eap.arpa realm . . . . . . . . . . . . . . . . . . . 4
3.2. The username field . . . . . . . . . . . . . . . . . . . 4
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Taxonomy of Provisioning Types . . . . . . . . . . . . . 5
4.1.1. Rationale for Provisioning over EAP . . . . . . . . . 5
5. Interaction with existing EAP types . . . . . . . . . . . . . 5
5.1. EAP-TLS . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. TLS-based EAP methods . . . . . . . . . . . . . . . . . . 7
5.3. EAP-NOOB . . . . . . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6.1. .arpa updates . . . . . . . . . . . . . . . . . . . . . . 7
6.1.1. Domain Name Reservation Considerations . . . . . . . 8
6.2. EAP Provisioning Identifier Registry . . . . . . . . . . 9
6.2.1. Initial Values . . . . . . . . . . . . . . . . . . . 10
6.3. Guidelines for Designated Experts . . . . . . . . . . . . 10
6.3.1. Example of Vendor Self Assignment . . . . . . . . . . 12
6.3.2. Example of Service Delivery Organization . . . . . . 12
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
10. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 13
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
In most uses, EAP [RFC3748] requires that the EAP peer have a known
identity. However, when the peer does not already have an identity,
this requirement creates a bootstrapping problem. It may not be
possible for the device to obtain network access without credentials.
However, credentials are usually required in order to obtain network
access. As a result, the device is unprovisioned, and unable to be
provisioned.
This specification addresses that problem. It creates a framework by
which clients can submit predefined credentials to a server in order
to obtain limited network access. At the same time, servers can know
in advance that these credentials are only to be used for
provisioning, and that unrestricted network access should not be
granted.
The device can either use the EAP channel itself for provisioning, as
with TEAP [RFC7170], or the EAP server can give the device access to
a limited captive portal such as with [RFC8952]. Once the device is
provisioned, it can use those provisioned credentials to obtain full
network access.
The identifiers used here are generically referred to as "EAP
Provisioning Identifiers" (EPI). The choice of "Provisioning
Identifiers for EAP" (PIE) was considered and rejected.
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.
3. Concepts
A device which has no device-specific credentials can use a
predefined identifier in Network Access Identifier (NAI) format
[RFC7542]. The NAI is composed of two portions, the utf8-username,
and the utf8-realm domain. For simplicity here, we refer to these as
the "username" and "realm" fields.
The realm is chosen to be non-routable, so that the EAP packet
exchange is not sent across an Authentication, Authorization, and
Accounting (AAA) proxy framework as defined in [RFC7542] Section 3.
Instead, the packets remains local to the EAP server. If the EAP
server implements this standard, then it can proceed with the full
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EAP conversation. If the EAP server does not implement this
standard, then it MUST reply with an EAP Failure, as per [RFC3748]
Section 4.2.
We note that this specification is fully compatible with all existing
EAP implementations, so its is fail-safe. When presented with a peer
wishing to use this specification, existing implementations will
return EAP Failure, and will not otherwise misbehave.
We now discuss the NAI format in more detail. We first discuss the
eap.arpa realm, and second the use and purpose of the username field.
3.1. The eap.arpa realm
This document defines the "eap.arpa" domain as being used for
provisioning within EAP. A similar domain has previously been used
for EAP-NOOB [RFC9140], as "eap-noob.arpa". This document extends
that concept, and standardizes the practices surrounding it,
NOTE: the "arpa" domain is controlled by the IAB. Allocation of
"eap.arpa" requires agreement from the IAB.
3.2. The username field
The username field is assigned via the EAP Provisioning Identifier
Registry which is defined below. The registry can either hold a
fixed string such as "noob", or a prefix such as "V-". Prefixes give
vendors and Service delivery organizations (SDOs) the ability to
self-assign a delegated range of identifiers which cannot conflict
with other identifiers.
The username field MUST NOT omitted. That is, "@eap.arpa" is not a
valid identifier for the purposes of this specification. [RFC7542]
recommends omitting the username portion for user privacy. As user
privacy is not needed here, the username field can be publicly
visible.
4. Overview
For EAP-TLS, both [RFC5216] Section 2.1.1 and [RFC9190] provide for
"peer unauthenticated access". However, those documents define no
way for a peer to signal that it is requesting such access. The
presumption is that the peer connects with some value for the EAP
Identity, but without using a client certificate. The EAP server is
then supposed to determine that the peer is requesting
unauthenticated access, and take the approprate steps to limit
authorization.
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There appears to be no EAP peer or server implementations which
support such access, since there is no defined way to perform any of
the steps required. i.e. to signal that this access is desired, and
then limit access.
TBD: The Wireless Broadband Alliance (WBA) has defined an
unauthenticated EAP-TLS method, using a vendor-specific EAP type.
Get link.
EAP-NOOB [RFC9140] takes this process a step further. It defines
both a way to signal that provisioning is desired, and also a way to
exchange provisioning information within EAP-NOOB. That is, there is
no need for the device to obtain limited network access, as all of
the provisioning is done inside of the EAP-NOOB protocol.
TEAP [RFC7170] provides for provisioning via an unauthenticated TLS
tunnel. There is a server unauthenticated provisioning mode (TBD),
but the inner TLS exchange requires that both end authenticate each
other. There are ways to provision a certificate, but the peer must
still authenticate itself to the server.
4.1. Taxonomy of Provisioning Types
There are two scenarios where provisioning can be done. The first is
where provisioning is done within the EAP type, as with EAP-NOOB
[RFC9140]. The second is where EAP is used to obtain limited network
access (e.g. as with a captive portal). That limited network access
is then used to run Internet Protocol (IP) based provisioning over
more complex protocols.
4.1.1. Rationale for Provisioning over EAP
It is often useful to do all provisioning inside of EAP, because the
EAP / AAA admin does not have control over the network. It is not
always possible to define a captive portal where provisioning can be
done. As a result, we need to be able to perform provisioning via
EAP, and not via some IP protocol.
5. Interaction with existing EAP types
As the provisioning identifer is used within EAP, it necessarily has
interactions with, and effects on, the various EAP types. This
section discusses those effects in more detail.
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Some EAP methods require shared credentials such as passwords in
order to succeed. For example, both EAP-MSCHAPv2 (PEAP) and EAP-PWD
[RFC5931] perform cryptographic exchanges where both parties knowing
a shared password. Where those methods are used, the password MUST
be the same as the provisioning identifier.
This requirement also applies to TLS-based EAP methods such as TTLS
and PEAP. Where the TLS-based EAP method provides for an inner
identity and inner authentication method, the credentials used there
MUST be the provisioning identifier for both the inner identity, and
any inner password.
This process ensures that most EAP methods will work for
provisioning, at the expense of potential security attacks. TBD -
discuss.
It is RECOMMENDED that provisioning be done via a TLS-based EAP
methods. TLS provides for authentication of the EAP server, along
with security and confidentiality of any provisioning data exchanged
in the tunnel. Similarly if provisioning is done in a captive portal
outside of EAP, EAP-TLS permits the EAP peer to run a full EAP
authentication session while having nothing more than a few
certification authorities (CAs) locally configured.
5.1. EAP-TLS
This document defines an identifier "portal@eap.arpa", which is the
first step towards permitted unauthenticated client provisioning in
EAP-TLS. The purpose of the identifier is to allow EAP peers to
signal EAP servers that they wish to obtain a "captive portal" style
network access.
This identifier signals the EAP server that the peer wishes to obtain
"peer unauthenticated access" as per [RFC5216] Section 2.1.1 and
[RFC9190].
An EAP server which agrees to authenticate this request MUST ensure
that the device is placed into a captive portal with limited network
access. Further details of the captive portal architecture can be
found in [RFC8952].
The remaining question is how the EAP peer verifies the identity of
the EAP server. The device SHOULD ignore the EAP server certificate
entirely, as the servers identity does not matter. Any verification
of servers can be done at the HTTPS layer when the device access the
captive portal. Where possible the device SHOULD warn the end user
that the provided certificate is unchecked, and untrusted.
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However, since the device likely is configured with web CAs
(otherwise the captive portal would also be unauthenticated), EAP
peers MAY use the CAs available for the web in order to validate the
EAP server certificate. If the presented certificate passes
validation, the device does not need to warn the end user that the
provided certificate is untrusted.
5.2. TLS-based EAP methods
Other TLS-based EAP methods such as TTLS and PEAP can use the same
method as defined for EAP-TLS above. The only difference is that the
inner identity and password is also the provisioning identifier.
Is is RECOMMENDED that provisioning methods use EAP-TLS in preference
to any other TLS-based EAP methods. As the credentials for other
methods are predefined and known in advanc, those methods offer
little benefit over EAP-TLS.
5.3. EAP-NOOB
It is RECOMMENDED that server implementations of EAP-NOOB accept both
identities "noob@eap-noob.arpa" and "noob@eap.arpa" as synonyms.
It is RECOMMENDED that EAP-NOOB peers use "noob@eap.arpa" first, and
if that does not succeed, use "noob@eap-noob.arpa"
@todo - what is the deployment of EAP-NOOB? Can we even make this
recommendation?
6. IANA Considerations
Three IANA actions are required. The first two are registry updates
for "eap.arpa". The second is the creation of a new registry.
6.1. .arpa updates
IANA is instructed to update the ".ARPA Zone Management" registry
with the following entry:
DOMAIN
eap.arpa
USAGE
For provisioning within the Extensible Authentication Protocol
framework.
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REFERENCE
THIS-DOCUMENT
IANA is instructed to update the "Special-Use Domain Names" registry
as follows:
NAME
eap.arpa
REFERENCE
THIS-DOCUMENT
6.1.1. Domain Name Reservation Considerations
This section answers the questions which are required by Section 5 of
[RFC6761]. At a high level, these new domain names are used in
certain situations in EAP. The domain names are never seen by users,
and they do not appear in any networking protocol other than EAP.
1. Users:
User are not expected to recognise these names as special or use
them differently from other domain names. The use of these names
in EAP is invisible to end users.
1. Application Software:
EAP servers and clients are expected to make their software
recognize these names as special and treat them differently. This
document discusses that behavor.
EAP supplicants should recognize these names as special, and
should refuse to allow users to enter them in any interface.
1. Name Resolution APIs and Libraries:
Writers of these APIs and libraries are not expected to recognize
these names or treat them differently.
1. Caching DNS Servers:
Writers of caching DNS servers are not expected to recognize these
names or treat them differently.
1. Authoritative DNS Servers:
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Writers of authoritative DNS servers are not expected to recognize
these names or treat them differently.
1. DNS Server Operators:
These domain names have no impact on DNS server operators. They
should never be used in DNS, or in any networking protocol outside
of EAP.
If they try to configure their authoritative DNS as authoritative
for this reserved name, compliant name servers do not need to do
anything special. They can accept the domain or reject it.
Either behavior will have no impact on this specification.
1. DNS Registries/Registrars:
DNS Registries/Registrars should deny requests to register this
reserved domain name.
6.2. EAP Provisioning Identifier Registry
IANA is instructed to add the following new registry to the
"Extensible Authentication Protocol (EAP) Registry" group.
Assignments in this registry are done via "Expert Review" as
described in [RFC8126] Section 4.5.
The contents of the registry are as follows.
Title
EAP Provisioning Identifiers
Registration Procedure(s)
Expert review
Reference
THIS-DOCUMENT
Registry
Name
The name of the identifier. Names are listed in sorted order,
case insensitive.
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Prefix
A boolean true/false flag indicating if this name is a prefix.
Description
Description of the use-cases for this identifier.
Reference
Reference where this identifier was defined.
6.2.1. Initial Values
The following table gives the initial values for this table.
Value,Prefix,Description,Reference
noob,false,EAP-NOOB,RFC9140 and THIS-DOCUMENT portal,false,generic
captive portal,THIS-DOCUMENT V-,true,reserved for vendor self-
assignment,THIS-DOCUMENT
6.3. Guidelines for Designated Experts
Identifiers and prefixes in the "Name" field of this registry MUST
satisfy the "utf8-username" format defined in [RFC7542] Section 2.2.
Identifiers should be unique when compared in a case-insensitive
fashion. While [RFC7542] notes that similar identifiers of different
case can be considered to be different, this registry is made simpler
by requiring case-insensitivity.
Identifiers and prefixes should be short. The NAIs created from
these prefixes will generally be sent in a RADIUS packet in the User-
Name attribute ([RFC2865] Section 5.1). That specification
recommends that implementations should support User-Names of at least
63 octets. NAI length considerations are further discussed in
[RFC7542] Section 2.3, and any allocations need to take those
limitations into consideration.
Implementations are likely to support a total NAI length of 63
octets. Lengths between 63 and 253 octets may work. Lengths of 254
octets or more will not work with RADIUS [RFC2865].
For registration requests where a Designated Expert should be
consulted, the responsible IESG area director should appoint the
Designated Expert. The intention is that any non-prefix allocation
will be accompanied by a published RFC. But in order to allow for
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the allocation of values prior to the RFC being approved for
publication, the Designated Expert can approve allocations once it
seems clear that an RFC will be published.
For allocation of a prefix, the Designated Expert should verify that
the requested prefix clearly identifies the organization requesting
the prefix, that there is a publicly available document from the
organization which describes the prefix, and that the prefix ends
with the "-" character.
Once a prefix has been assigned, it is not possible to perform
further allocations in this registry which use that prefix. All such
allocations have instead been delegated to the external organization.
The Designated expert will post a request to the EMU WG mailing list
(or a successor designated by the Area Director) for comment and
review, including an Internet-Draft or reference to external
specification. Before a period of 30 days has passed, the Designated
Expert will either approve or deny the registration request and
publish a notice of the decision to the EAP WG mailing list or its
successor, as well as informing IANA. A denial notice must be
justified by an explanation, and in the cases where it is possible,
concrete suggestions on how the request can be modified so as to
become acceptable should be provided.
A short-hand summary of the requirements follows:
* Identifiers and prefixes in the "Name" field of this registry MUST
satisfy the "utf8-username" format defined in [RFC7542]
Section 2.2.
* Names MUST be unique, compared in a case-insensitive fashion.
* Prefixes MUST NOT overlap with the beginning any other identifier.
That is, if the prefix "foo-" has been allocated, then an
identifier of "foo-bar" MUST NOT be allocated.
* If the "prefix" flag is "false", then the Name field MUST NOT end
with the "-" character.
* If the "prefix" flag is "true", then the Name field MUST end with
the "-" character.
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6.3.1. Example of Vendor Self Assignment
Identifiers beginning with "V-" are for vendor self-assignment. The
name MUST begin with the string "V-", following by 1 or more digits
(0-9). The digits used here are taken from the vendor private
enterprise number (PEN).
The name MUST then contain another "-" which delineates the vendor
specific suffix namespace. The suffix is managed and allocated by
the vendor, and does not need to be added to the registry.
The suffix is text which matches the "dot-string" definition of
[RFC7542] Section 2.2.
For example, an identifier chosen by Cisco (PEN of 9) could be:
V-9-foo
Which then creates an NAI of the form:
V-9-foo@eap.arpa
6.3.2. Example of Service Delivery Organization
Service delivery organizations (SDOs) can request allocations of
prefixes for use within their SDO. The prefix should be the name
(abbreviated where possible) of the SDO, followed by a "-" character.
The suffix is managed and allocated by the SDO, and does not need to
be added to the registry.
The suffix is text which matches the "dot-string" definition of
[RFC7542] Section 2.2.
For example, the 3rd Generation Partnership Project (3GPP) could
request a prefix "3gpp-", and then self-assign a suffix "baz", to
create an identifier:
3gpp-baz
Which then creates an NAI of the form:
3gpp-baz@eap.arpa
7. Privacy Considerations
TBD
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8. Security Considerations
TBD
9. Acknowledgements
TBD.
10. Changelog
* 00 - initial version
* 01 - add "Domain Name Reservation Considerations"
11. References
11.1. Normative References
[BCP14] 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/rfc/rfc8174>.
[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/rfc/rfc2119>.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
<https://www.rfc-editor.org/rfc/rfc3748>.
[RFC5216] Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS
Authentication Protocol", RFC 5216, DOI 10.17487/RFC5216,
March 2008, <https://www.rfc-editor.org/rfc/rfc5216>.
[RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542,
DOI 10.17487/RFC7542, May 2015,
<https://www.rfc-editor.org/rfc/rfc7542>.
[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/rfc/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/rfc/rfc8174>.
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[RFC9140] Aura, T., Sethi, M., and A. Peltonen, "Nimble Out-of-Band
Authentication for EAP (EAP-NOOB)", RFC 9140,
DOI 10.17487/RFC9140, December 2021,
<https://www.rfc-editor.org/rfc/rfc9140>.
[RFC9190] Preuß Mattsson, J. and M. Sethi, "EAP-TLS 1.3: Using the
Extensible Authentication Protocol with TLS 1.3",
RFC 9190, DOI 10.17487/RFC9190, February 2022,
<https://www.rfc-editor.org/rfc/rfc9190>.
11.2. Informative References
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, DOI 10.17487/RFC2865, June 2000,
<https://www.rfc-editor.org/rfc/rfc2865>.
[RFC5931] Harkins, D. and G. Zorn, "Extensible Authentication
Protocol (EAP) Authentication Using Only a Password",
RFC 5931, DOI 10.17487/RFC5931, August 2010,
<https://www.rfc-editor.org/rfc/rfc5931>.
[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, DOI 10.17487/RFC6761, February 2013,
<https://www.rfc-editor.org/rfc/rfc6761>.
[RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
"Tunnel Extensible Authentication Protocol (TEAP) Version
1", RFC 7170, DOI 10.17487/RFC7170, May 2014,
<https://www.rfc-editor.org/rfc/rfc7170>.
[RFC8952] Larose, K., Dolson, D., and H. Liu, "Captive Portal
Architecture", RFC 8952, DOI 10.17487/RFC8952, November
2020, <https://www.rfc-editor.org/rfc/rfc8952>.
Author's Address
Alan DeKok
FreeRADIUS
Email: aland@freeradius.org
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