draft-ietf-radext-dynamic-discovery-06.txt   draft-ietf-radext-dynamic-discovery-07.txt 
RADIUS Extensions Working Group S. Winter RADIUS Extensions Working Group S. Winter
Internet-Draft RESTENA Internet-Draft RESTENA
Intended status: Experimental M. McCauley Intended status: Experimental M. McCauley
Expires: August 29, 2013 OSC Expires: January 05, 2014 OSC
February 25, 2013 July 04, 2013
NAI-based Dynamic Peer Discovery for RADIUS/TLS and RADIUS/DTLS NAI-based Dynamic Peer Discovery for RADIUS/TLS and RADIUS/DTLS
draft-ietf-radext-dynamic-discovery-06 draft-ietf-radext-dynamic-discovery-07
Abstract Abstract
This document specifies a means to find authoritative RADIUS servers This document specifies a means to find authoritative RADIUS servers
for a given realm. It is used in conjunction with either RADIUS/TLS for a given realm. It is used in conjunction with either RADIUS/TLS
and RADIUS/DTLS. and RADIUS/DTLS.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2013. This Internet-Draft will expire on January 05, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. DNS-based NAPTR/SRV Peer Discovery . . . . . . . . . . . . . 3 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 2.1. DNS RR definition . . . . . . . . . . . . . . . . . . . . 3
2.2. DNS RR definition . . . . . . . . . . . . . . . . . . . . 3 2.1.1. S-NAPTR . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Realm to RADIUS server resolution algorithm . . . . . . . 6 2.1.2. SRV . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.1. Input . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1.3. Remarks . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.2. Output . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. Definition of the X.509 certificate property
2.3.3. Algorithm . . . . . . . . . . . . . . . . . . . . . . 7 SubjectAltName:otherName:NAIRealm . . . . . . . . . . . . 10
2.3.4. Validity of results . . . . . . . . . . . . . . . . . 8 3. DNS-based NAPTR/SRV Peer Discovery . . . . . . . . . . . . . 11
2.3.5. Delay considerations . . . . . . . . . . . . . . . . 9 3.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 11
2.3.6. Example . . . . . . . . . . . . . . . . . . . . . . . 9 3.2. Configuration Variables . . . . . . . . . . . . . . . . . 11
3. Security Considerations . . . . . . . . . . . . . . . . . . . 11 3.3. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 3.4. Realm to RADIUS server resolution algorithm . . . . . . . 12
5. Normative References . . . . . . . . . . . . . . . . . . . . 12 3.4.1. Input . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 3.4.2. Output . . . . . . . . . . . . . . . . . . . . . . . 13
3.4.3. Algorithm . . . . . . . . . . . . . . . . . . . . . . 13
3.4.4. Validity of results . . . . . . . . . . . . . . . . . 15
3.4.5. Delay considerations . . . . . . . . . . . . . . . . 16
3.4.6. Example . . . . . . . . . . . . . . . . . . . . . . . 16
4. Security Considerations . . . . . . . . . . . . . . . . . . . 19
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6. Normative References . . . . . . . . . . . . . . . . . . . . 20
Appendix A. Appendix A: ASN.1 Syntax of NAIRealm . . . . . . . . 21
1. Introduction 1. Introduction
RADIUS in all its current transport variants (RADIUS/UDP, RADIUS/TLS, RADIUS in all its current transport variants (RADIUS/UDP, RADIUS/TLS,
RADIUS/DTLS) requires manual configuration of all peers (clients, RADIUS/DTLS) requires manual configuration of all peers (clients,
servers). servers).
Where RADIUS forwarding servers are in use, the number of realms to Where RADIUS forwarding servers are in use, the number of realms to
be forwarded and the corresponding number of servers to configure may be forwarded and the corresponding number of servers to configure may
be significant. Where new realms with new servers are added or be significant. Where new realms with new servers are added or
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independently working branches, each with their own forwarding independently working branches, each with their own forwarding
servers, and who add or change their realm lists at their own servers, and who add or change their realm lists at their own
discretion, there is additional complexity in synchronising the discretion, there is additional complexity in synchronising the
changed data across all branches. changed data across all branches.
These situations can benefit significantly from a distributed These situations can benefit significantly from a distributed
mechanism for storing realm and server reachability information. mechanism for storing realm and server reachability information.
This document describes one such mechanism: storage of realm-to- This document describes one such mechanism: storage of realm-to-
server mappings in DNS. server mappings in DNS.
This document does not specify how to verify that server information This document also specifies various approaches for verifying that
which was retrieved from DNS was from an authorised party; e.g. an server information which was retrieved from DNS was from an
organisation which is not at all part of a given roaming consortium authorised party; e.g. an organisation which is not at all part of a
may alter its own DNS records to yield a result for its own realm. given roaming consortium may alter its own DNS records to yield a
result for its own realm.
RADIUS/TLS and RADIUS/DTLS have their own ways how to verify that a
contacted peer is authorised (e.g. by presenting PKIX certificates
from a agreed-upon CA).
1.1. Requirements Language 1.1. Requirements Language
In this document, several words are used to signify the requirements In this document, several words are used to signify the requirements
of the specification. The key words "MUST", "MUST NOT", "REQUIRED", of the specification. The key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" in this document are to be interpreted as described in and "OPTIONAL" in this document are to be interpreted as described in
RFC 2119. [RFC2119] RFC 2119. [RFC2119]
1.2. Terminology 1.2. Terminology
RADIUS/TLS Client: a RADIUS/TLS [RFC6614] instance which initiates a RADIUS/TLS Client: a RADIUS/TLS [RFC6614] instance which initiates a
new connection. new connection.
RADIUS/TLS Server: a RADIUS/TLS [RFC6614] instance which listens on a RADIUS/TLS Server: a RADIUS/TLS [RFC6614] instance which listens on a
RADIUS/TLS port and accepts new connections RADIUS/TLS port and accepts new connections
RADIUS/TLS node: a RADIUS/TLS client or server RADIUS/TLS node: a RADIUS/TLS client or server
2. DNS-based NAPTR/SRV Peer Discovery 2. Definitions
2.1. Applicability
Dynamic server discovery as defined in this document is only
applicable for AAA transactions where a RADIUS entity which acts as a
forwarding server for one or more realms receives a request with a
realm for which it is not authoritative, and which no explicit next
hop is configured. Furthermore, it is only applicable for new user
sessions, i.e. for the initial Access-Request. Subsequent messages
concerning this session, for example Access-Challenges and Access-
Accepts use the previously-established communication channel between
client and server.
2.2. DNS RR definition 2.1. DNS RR definition
DNS definitions of RADIUS/TLS servers can be either S-NAPTR records DNS definitions of RADIUS/TLS servers can be either S-NAPTR records
(see [RFC3958]) or SRV records. When both are defined, the (see [RFC3958]) or SRV records. When both are defined, the
resolution algorithm prefers S-NAPTR results (see Section 2.3 below). resolution algorithm prefers S-NAPTR results (see Section 3.4 below).
2.1.1. S-NAPTR
2.1.1.1. Registration of Application Service and Protocol Tags
This specification defines three S-NAPTR service tags: This specification defines three S-NAPTR service tags:
+-----------------+-----------------------------------------+ +-----------------+-----------------------------------------+
| Service Tag | Use | | Service Tag | Use |
+-----------------+-----------------------------------------+ +-----------------+-----------------------------------------+
| aaa+auth | RADIUS Authentication, i.e. traffic as | | aaa+auth | RADIUS Authentication, i.e. traffic as |
| | defined in [RFC2865] | | | defined in [RFC2865] |
| - - - - - - - - | - - - - - - - - - - - - - - - - - - - - | | - - - - - - - - | - - - - - - - - - - - - - - - - - - - - |
| aaa+acct | RADIUS Accounting, i.e. traffic as | | aaa+acct | RADIUS Accounting, i.e. traffic as |
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| | in [I-D.ietf-radext-dtls] | | | in [I-D.ietf-radext-dtls] |
+-----------------+-----------------------------------------+ +-----------------+-----------------------------------------+
Figure 2: List of Protocol Tags Figure 2: List of Protocol Tags
Note well: Note well:
The S-NAPTR service and protocols are unrelated to the IANA The S-NAPTR service and protocols are unrelated to the IANA
Service Name and Transport Protocol Number registry Service Name and Transport Protocol Number registry
The delimiter '.' in the protocol tags is only a separator for The delimiter '.' in the protocol tags is only a separator for
human reading convenience - not for structure or namespacing; it human reading convenience - not for structure or namespacing; it
MUST NOT be parsed in any way by the querying application or MUST NOT be parsed in any way by the querying application or
resolver. resolver.
The use of the separator '.' is common also in other protocols' The use of the separator '.' is common also in other protocols'
protocol tags. This is coincidence and does not imply a shared protocol tags. This is coincidence and does not imply a shared
semantics with such protocols. semantics with such protocols.
This specification defines two SRV prefixes (i.e. two values for the 2.1.1.2. Definition of Conditions for Retry/Failure
"_service._proto" part of an SRV RR):
RADIUS is a time-critical protocol; RADIUS clients which do not
receive an answer after a configurable, but short, amount of time,
will consider the request failed. Due to this, there is little
leeway for extensive retries.
As a general rule, only error conditions which generate an immediate
response from the other end are eligible for a retry of a discovered
target. Any error condition involving time-outs, or the absence of a
reply for more than one second during the connection setup phase is
to be considered a failure; the next target in the set of discovered
NAPTR targets is to be tried.
Note that [RFC3958] already defines that a failure to identify the
server as being authoritative for the realm is always considered a
failure; so even if a discovered target returns a wrong credential
instantly, it is not eligible for retry.
Furthermore, the contacted RADIUS/TLS server verifies during
connection setup whether or not it finds the connecting RADIUS/TLS
client authorized or not. If the connecting RADIUS/TLS client is not
found acceptable, the server will close the TLS connection
immediately with an appropriate alert. Such TLS handshake failures
are permanently fatal and not eligible for retry.
2.1.1.3. Server Identification and Handshake
After the algorithm in this document has been executed, a RADIUS/TLS
session as per [RFC6614] is established. Since the algorithm does
not allow to derive confidential keying material between the RADIUS/
TLS client (i.e. the server which executes the discovery algorithm)
and the RADIUS/TLS server which was discovered, TLS-PSK ciphersuites
can not be used for the subsequent TLS handshake in the RADIUS/TLS
conversation. Only TLS ciphersuites using X.509 certificates can be
used with this algorithm.
There are numerous ways to define which certificates are acceptable
for use in this context. This document defines one mandatory-to-
implement mechanism which allows to verify whether the contacted host
is authoritative for a NAI realm or not. It also gives one example
of another mechanism which is currently in wide-spread deployment,
and one possible approach based on DNSSEC which is yet unimplemented.
2.1.1.3.1. Mandatory-to-implement mechanism: Trust Roots + NAIRealm
Verification of authority to provide AAA services over RADIUS/TLS is
a two-step process.
Step 1 is the verification of certificate wellformedness and validity
as per [RFC5280] and whether it was issued from a root certificate
which is deemed trustworthy by the RADIUS/TLS client.
Step 2 is: compare the value of algorithm's variable "R" after the
execution of step 3 of the discovery algorithm in Section 3.4.3 below
(i.e. after a consortium name mangling, but before conversion to a
form usable by the name resolution library) to all values of the
contacted RADIUS/TLS server's X.509 certificate property
"subjectAlternativeName:otherName:NAIRealm" as defined in
Section 2.2. The comparison is a byte-by-byte comparison, except for
dot-separated parts of the value whose content is a single "*"
character; such labels match all strings in the same part of the NAI
realm. If at least one of the sAN:otherName:NAIRealm values matches
the NAI realm, the server is considered authorized; if none matches,
the server is considered unauthorized.
Examples:
+-----------------+---------------------------------------------+
| NAI realm | sAN:otherName:NAIRealm | MATCH? |
+-----------------+---------------------------------------------+
| foo.example | foo.example | YES |
| foo.example | *.example | YES |
| bar.foo.example | *.example | NO |
| bar.foo.example | bar.*.example | YES |
| bar.foo.example | *.*.example | YES |
| sub.bar.foo.example | *.*.example | NO |
| sub.bar.foo.example | sub.bar.foo.example | YES |
+-----------------+---------------------------------------------+
Figure 3: Examples for NAI realm vs. certificate matching
2.1.1.3.2. Other mechanism: Trust Roots + policyOID
Verification of authority to provide AAA services over RADIUS/TLS is
a two-step process.
Step 1 is the verification of certificate wellformedness and validity
as per [RFC5280] and whether it was issued from a root certificate
which is deemed trustworthy by the RADIUS/TLS client.
Step 2 is: compare the values of the contacted RADIUS/TLS server's
X.509 certificate's extensions of type "Policy OID" to a list of
configured acceptable Policy OIDs for the roaming consortium. If one
of the configured OIDs is found in the certificate's Policy OID
extensions, then the server is considered authorized; if there is no
match, the server is considered unauthorized.
This mechanism is inferior to the mandatory-to-implement mechanism in
the previous section because all authorized servers are validated by
the same OID value; the mechanism is not fine-grained enough to
express authority for one specific realm inside the consortium. If
the consortium contains members which are hostile against other
members, this weakness can be exploited by one RADIUS/TLS server
impersonating another if DNS responses can be spoofed by the hostile
member.
It should be noted that these shortcomings can be mitigated by using
the RADIUS infrastructure only with authentication payloads which
provide mutual authentication; that way, the final EAP server that
was reached can be validated by the EAP peer, and any improper
redirections to a different server will be detected.
2.1.1.3.3. Other mechanism: DNSSEC / DANE
Where DNSSEC is used, the results of the algorithm can be trusted;
i.e. the entity which executes the algorithm can be certain that the
realm that triggered the discovery is actually served by the server
that was discovered via DNS. However, this does not guarantee that
the server is also authorized (i.e. a recognised member of the
roaming consortium).
The authorization can be sketched using DNSSEC+DANE as follows: if
DANE/TLSA records of all authorized servers are put into a DNSSEC
zone with a common, consortium-specific branch of the DNS tree, then
the entity executing the algorithm can retrieve TLSA RRs for the
label "realm.commonroot" and verify that the presented server
certificate during the RADIUS/TLS handshake matches the information
in the TLSA record.
Example:
Realm = "example.com"
Common Branch = "idp.roaming-consortium.example.
label for TLSA query = "example.com.idp.roaming-
consortium.example.
result of discovery algorithm for realm "example.com" =
192.0.2.1:2083
( TLS certificate of 192.0.2.1:2083 matches TLSA RR ? "PASS" :
"FAIL" )
2.1.1.3.4. Remark
Note that RADIUS/TLS connections always mutually authenticate the
RADIUS server and the RADIUS client. This specification provides an
algorithm for a RADIUS client to contact and verify authorization of
a RADIUS server only. During connection setup, the RADIUS server
also needs to verify whether it considers the connecting RADIUS
client authorized; this is outside the scope of this specification.
2.1.2. SRV
This specification defines two SRV prefixes (i.e. two values for the
"_service._proto" part of an SRV RR as per [RFC2782]):
+-----------------+-----------------------------------------+ +-----------------+-----------------------------------------+
| SRV Label | Use | | SRV Label | Use |
+-----------------+-----------------------------------------+ +-----------------+-----------------------------------------+
| _radiustls._tcp | RADIUS transported over TLS as defined | | _radiustls._tcp | RADIUS transported over TLS as defined |
| | in [RFC6614] | | | in [RFC6614] |
| - - - - - - - - | - - - - - - - - - - - - - - - - - - - - | | - - - - - - - - | - - - - - - - - - - - - - - - - - - - - |
| _radiustls._udp | RADIUS transported over DTLS as defined | | _radiustls._udp | RADIUS transported over DTLS as defined |
| | in [I-D.ietf-radext-dtls] | | | in [I-D.ietf-radext-dtls] |
+-----------------+-----------------------------------------+ +-----------------+-----------------------------------------+
Figure 3: List of SRV Labels Figure 4: List of SRV Labels
Just like NAPTR records, the lookup and subsequent follow-up of SRV
records may yield more than one server to contact in a prioritised
list. [RFC2782] does not specify rules regarding "Definition of
Conditions for Retry/Failure", nor "Server Identification and
Handshake". This specification defines that the rules for these two
topics as defined in Section 2.1.1.2 and Section 2.1.1.3 SHALL be
used both for targets retrieved via an initial NAPTR RR as well as
for targets retrieved via an initial SRV RR (i.e. in the absence of
NAPTR RRs).
2.1.3. Remarks
It is expected that in most cases, the SRV and/or NAPTR label used It is expected that in most cases, the SRV and/or NAPTR label used
for the records is the DNS A-label representation of the literal for the records is the DNS A-label representation of the literal
realm name for which the server is the authoritative RADIUS server realm name for which the server is the authoritative RADIUS server
(i.e. the realm name after conversion according to section 5 of (i.e. the realm name after conversion according to section 5 of
[RFC5891]). [RFC5891]).
However, arbitrary other SRV and/or NAPTR labels may be used if, for However, arbitrary other labels or service tags may be used if, for
example, a roaming consortium uses realm names which are not example, a roaming consortium uses realm names which are not
associated to DNS names or special-purpose consortia where a globally associated to DNS names or special-purpose consortia where a globally
valid discovery is not a use case. Such other labels require a valid discovery is not a use case. Such other labels require a
consortium-wide agreement about the transformation from realm name to consortium-wide agreement about the transformation from realm name to
lookup label. lookup label, and/or which service tag to use.
Examples: Examples:
a. A general-purpose RADIUS server for realm example.com might have a. A general-purpose RADIUS server for realm example.com might have
DNS entries as follows: DNS entries as follows:
example.com. IN NAPTR 50 50 "s" "aaa+auth:radius.tls" "" example.com. IN NAPTR 50 50 "s" "aaa+auth:radius.tls" ""
_radiustls._tcp.foobar.example.com. _radiustls._tcp.foobar.example.com.
_radiustls._tcp.foobar.example.com. IN SRV 0 10 2083 _radiustls._tcp.foobar.example.com. IN SRV 0 10 2083
radsec.example.com. radsec.example.com.
b. The consortium "foo" provides roaming services for its members b. The consortium "foo" provides roaming services for its members
only. The realms used are of the form enterprise-name.example. only. The realms used are of the form enterprise-name.example.
The consortium operates a special purpose DNS server for the The consortium operates a special purpose DNS server for the
(private) TLD "example" which all RADIUS servers use to resolve (private) TLD "example" which all RADIUS servers use to resolve
realm names. "Bad, Inc." is part of the consortium. On the realm names. "Bad, Inc." is part of the consortium. On the
consortium's DNS server, realm bad.example might have the consortium's DNS server, realm bad.example might have the
following DNS entries: following DNS entries:
bad.example IN NAPTR 50 50 "a" "aaa+auth:radius.dtls" "" bad.example IN NAPTR 50 50 "a" "aaa+auth:radius.dtls" ""
very.bad.example very.bad.example
c. The eduroam consortium uses realms based on DNS, but provides its c. The eduroam consortium uses realms based on DNS, but provides its
services to a closed community only. However, a AAA domain services to a closed community only. However, a AAA domain
participating in eduroam may also want to expose AAA services to participating in eduroam may also want to expose AAA services to
other, general-purpose, applications (on the same or other RADIUS other, general-purpose, applications (on the same or other RADIUS
skipping to change at page 6, line 23 skipping to change at page 10, line 5
example.org. IN NAPTR 50 50 "s" "aaa+auth:radius.tls" "" example.org. IN NAPTR 50 50 "s" "aaa+auth:radius.tls" ""
_radiustls._tcp.aaa.example.org _radiustls._tcp.aaa.example.org
_radiustls._tcp.eduroam.example.org. IN SRV 0 10 2083 aaa- _radiustls._tcp.eduroam.example.org. IN SRV 0 10 2083 aaa-
eduroam.example.org. eduroam.example.org.
_radiustls._tcp.aaa.example.org. IN SRV 0 10 2083 aaa- _radiustls._tcp.aaa.example.org. IN SRV 0 10 2083 aaa-
default.example.org. default.example.org.
2.3. Realm to RADIUS server resolution algorithm 2.2. Definition of the X.509 certificate property
SubjectAltName:otherName:NAIRealm
This algorithm can be used to discover RADIUS servers (for RADIUS This specification retrieves IP addresses and port numbers from the
Authentication and RADIUS Accounting) or to discover RADIUS DynAuth Domain Name System which are subsequently used to authenticate users
servers. via the RADIUS/TLS protocol. Since the Domain Name System is not
necessarily trustworthy (e.g. if DNSSEC is not deployed for the
queried domain name), it is important to verify that the server which
was contacted is authorized to service requests for the user which
triggered the discovery process.
2.3.1. Input The input to the algorithm is a NAI realm as specified in
Section 3.4.1. As a consequence, the X.509 certificate of the server
which is ultimately contacted for user authentication needs to be
able to express that it is authorized to handle requests for that
realm.
Current subjectAltName fields do not semantically allow to express an
NAI realm; the field subjectAltName:dNSName is syntactically a good
match but would inappropriately conflate DNS names and NAI realm
names. Thus, this specification defines a new subjectAltName field
to hold either a single NAI realm name or a wildcard name matching a
set of NAI realms.
The subjectAltName:otherName:sRVName field certifies that a
certificate holder is authorized to provide a service; this can be
compared to the target of DNS label's SRV resource record. If the
Domain Name System is insecure, it is required that the label of the
SRV record itself is known-correct. In this specification, that
label is not known-correct; it is potentially derived from a
(potentially untrusted) NAPTR resource record of another label. If
DNS is not secured with DNSSEC, the NAPTR resource record may have
been altered by an attacker with access to the Domain Name System
resolution, and thus the label to lookup the SRV record for may
already be tainted. This makes subjectAltName:otherName:sRVName not
a trusted comparison item.
Further to this, this specification's NAPTR entries may be of type
"A" which do not involve resolution of any SRV records, which again
makes subjectAltName:otherName:sRVName unsuited for this purpose.
This section defines the NAIRealm name as a form of otherName from
the GeneralName structure in SubjectAltName defined in [RFC5280].
id-on-nai OBJECT IDENTIFIER ::= { id-on XXX }
NAIRealm ::= UTF8String (SIZE (1..MAX))
The NAIRealm, if present, MUST contain an NAI realm as defined in
[I-D.ietf-radext-nai]. It MAY substitute labels on all dot-separated
parts of the NAI with the single character "*" to indicate a wildcard
match for "all labels in this part". Further features of regular
expressions, such as a number of characters followed by a * to
indicate a common prefix inside the part, are not permitted.
This subjectAltName MAY occur more than once in a certificate.
Appendix A contains the ASN.1 definition of the above objects.
3. DNS-based NAPTR/SRV Peer Discovery
3.1. Applicability
Dynamic server discovery as defined in this document is only
applicable for AAA transactions where a RADIUS entity which acts as a
forwarding server for one or more realms receives a request with a
realm for which it is not authoritative, and which no explicit next
hop is configured. It is only applicable for
a. new user sessions, i.e. for the initial Access-Request.
Subsequent messages concerning this session, for example Access-
Challenges and Access-Accepts use the previously-established
communication channel between client and server.
b. RADIUS DynAuth server discovery
3.2. Configuration Variables
The algorithm contains various variables for timeouts. These
variables are named here and reasonable default values are provided.
Implementations wishing to deviate from these defaults should make
they understand the implications of changes.
DNS_TIMEOUT: maximum amount of time to wait for the complete set
of all DNS queries to complete: Default = 3 seconds
MIN_EFF_TTL: minimum DNS TTL of discovered targets: Default = 60
seconds
BACKOFF_TIME: if no conclusive DNS response was retrieved after
DNS_TIMEOUT, do not attempt dynamic discovery before BACKOFF_TIME
has elapsed. Default = 600 seconds
3.3. Terms
Positive DNS response: a response which contains the RR that was
queried for.
Negative DNS response: a response which does not contain the RR that
was queried for, but contains an SOA record along with a TTL
indicating cache duration for this negative result.
DNS Error: Where the algorithm states "name resolution returns with
an error", this shall mean that either the DNS request timed out, or
a DNS response which is neither a positive nor a negative response
(e.g. SERVFAIL).
Effective TTL: The validity period for discovered RADIUS/TLS target
hosts. Calculated as: Effective TTL (set of DNS TTL values) = max {
MIN_EFF_TTL, min { DNS TTL values } }
SRV lookup: for the purpose of this specification, SRV lookup
procedures are defined as per [RFC2782], but excluding that RFCs "A"
fallback as defined in its section "Usage Rules", final "else"
clause.
3.4. Realm to RADIUS server resolution algorithm
3.4.1. Input
For RADIUS Authentication and RADIUS Accounting server discovery, For RADIUS Authentication and RADIUS Accounting server discovery,
input I to the algorithm is the RADIUS User-Name attribute with input I to the algorithm is the RADIUS User-Name attribute with
content of the form "user@realm"; the literal @ sign being the content of the form "user@realm"; the literal @ sign being the
separator between a local user identifier within a realm and its separator between a local user identifier within a realm and its
realm. The use of multiple literal @ signs in a User-Name is realm. The use of multiple literal @ signs in a User-Name is
strongly discouraged; but if present, the last @ sign is to be strongly discouraged; but if present, the last @ sign is to be
considered the separator. All previous instances of the @ sign are considered the separator. All previous instances of the @ sign are
to be considered part of the local user identifier. to be considered part of the local user identifier.
skipping to change at page 7, line 25 skipping to change at page 13, line 23
UTF-8 realms which end with a . ("dot") character. UTF-8 realms which end with a . ("dot") character.
For the last bullet point, "trailing dot", special precautions should For the last bullet point, "trailing dot", special precautions should
be taken to avoid problems when resolving servers with the algorithm be taken to avoid problems when resolving servers with the algorithm
below: they may resolve to a RADIUS server even if the peer RADIUS below: they may resolve to a RADIUS server even if the peer RADIUS
server only is configured to handle the realm without the trailing server only is configured to handle the realm without the trailing
dot. If that RADIUS server again uses NAI discovery to determine the dot. If that RADIUS server again uses NAI discovery to determine the
authoritative server, the server will forward the request to authoritative server, the server will forward the request to
localhost, resulting in a tight endless loop. localhost, resulting in a tight endless loop.
2.3.2. Output 3.4.2. Output
Output O of the algorithm is a set of tuples {hostname; port; order/ Output O of the algorithm is a two-tuple consisting of: O-1) a set of
preference; TTL} - the set can be empty. tuples {hostname; port; order/preference; Effective TTL} - the set
can be empty; and O-2) an integer: if the set in the first part of
the tuple is empty, the integer contains the Effective TTL for
backoff timeout, if the set is not empty, the integer is set to 0
(and not used).
2.3.3. Algorithm 3.4.3. Algorithm
The algorithm to determine the RADIUS server to contact is as The algorithm to determine the RADIUS server to contact is as
follows: follows:
1. Determine P = (position of last "@" character) in I. 1. Determine P = (position of last "@" character) in I.
2. generate R = (substring from P+1 to end of I) 2. generate R = (substring from P+1 to end of I)
3. Optional: modify R according to agreed consortium procedures 3. modify R according to agreed consortium procedures if applicable
4. Using the host's name resolution library, perform a NAPTR query 4. convert R to a representation usable by the name resolution
for R (see "Delay considerations" below). The name resolution library if needed
library may need to convert R to a different respresentation,
depending on the resolution backend used. If no result,
continue at step 9. If name resolution returns with error, O =
{ empty set } and terminate.
5. Extract NAPTR records with service tag "aaa+auth", "aaa+acct", 5. Initialize TIMER = 0; start TIMER. If TIMER reaches
DNS_TIMEOUT, continue at step 20.
6. Using the host's name resolution library, perform a NAPTR query
for R (see "Delay considerations" below). If the result is a
negative DNS response, O-2 = Effective TTL ( TTL value of the
SOA record ) and continue at step 13. If name resolution
returns with error, O-1 = { empty set }, O-2 = BACKOFF_TIME and
terminate.
7. Extract NAPTR records with service tag "aaa+auth", "aaa+acct",
"aaa+dynauth" as appropriate. Keep note of the remaining TTL of "aaa+dynauth" as appropriate. Keep note of the remaining TTL of
each of the discovered NAPTR records. each of the discovered NAPTR records.
6. If no records found, continue at step 9. 8. If no records found, continue at step 13.
7. Evaluate NAPTR result(s) for desired protocol tag, perform 9. For the extracted NAPTRs, perform successive resolution as
subsequent lookup steps until lookup yields one or more defined in [RFC3958], section 2.2.4, with the additional
hostnames. O' = (set of {hostname; port; order/preference; reservation that all records are to be immediately pursued
min{all TTLs that led to this result} } for all lookup results). through terminal lookup, i.e. have resulted in hostnames.
Keep note of the remaining TTL of each of the discovered records Failure to achieve terminal lookup for individual records is
(e.g. SRV and AAAA). non-fatal.
8. Proceed with step 15. 10. If the set of hostnames is empty, O-1 = { empty set }, O-2 =
BACKOFF_TIME and terminate.
9. Generate R' = (prefix R with "_radiustls._tcp." or 11. O' = (set of {hostname; port; order/preference; Effective TTL (
"_radiustls._udp") all DNS TTLs that led to this hostname ) } for all terminal
lookup results).
10. Using the host's name resolution library, perform SRV lookup 12. Proceed with step 18.
with R' as label (see "Delay considerations" below). Keep note
of the TTL of each of the discovered SRV records.
11. If name resolution returns with error, O = { empty set } and 13. Generate R' = (prefix R with "_radiustls._tcp." or
terminate. "_radiustls._udp.")
12. If no result, O = { empty set } and terminate. 14. Using the host's name resolution library, perform SRV lookup
with R' as label (see "Delay considerations" below).
13. O' = (set of {hostname; port; order/preference; min{all TTLs 15. If name resolution returns with error, O-1 = { empty set }, O-2
that led to this result} } for all hostnames). = BACKOFF_TIME and terminate.
14. Generate O by resoving hostnames to corresponding A and/or AAAA 16. If the result is a negative DNS response, O-1 = { empty set },
addresses: O = (set of {IP address; port; order/preference; O-2 = min { O-2, Effective TTL ( TTL value of the SOA record ) }
min{all TTLs that led to this result}} for all hostnames ). and terminate.
15. For each element in O, test if the original request which 17. O' = (set of {hostname; port; order/preference; Effective TTL (
all DNS TTLs that led to this result ) } for all hostnames).
18. Generate O-1 by resolving hostnames in O' into corresponding A
and/or AAAA addresses: O-1 = (set of {IP address; port; order/
preference; Effective TTL ( all DNS TTLs that led to this result
) } for all hostnames ), O-2 = 0.
19. For each element in O-1, test if the original request which
triggered dynamic discovery was received on {IP address; port}. triggered dynamic discovery was received on {IP address; port}.
If yes, O = { empty set }, log error, Terminate. If no, O is If yes, O-1 = { empty set }, O-2 = BACKOFF_TIME, log error,
the result of dynamic discovery. Terminate. Terminate (see next section for a rationale). If no, O is the
result of dynamic discovery. Terminate.
2.3.4. Validity of results 20. O-1 = { empty set }, O-2 = BACKOFF_TIME, log error, Terminate.
3.4.4. Validity of results
The dynamic discovery algorithm is used by servers which do not have
sufficient configuration information to process an incoming request
on their own. If the discovery algorithm result contains the
server's own listening address (IP address and port), then this will
either lead to a tight loop (if that DNS entry has topmost priority,
the server would forward the request to itself, triggering dynamic
discovery again in a perpetual loop), or lead to a potential loop
with intermediate hops in between (the server could forward to
another host with a higher priority, which might use DNS itself and
forward the packet back to the first server). The underlying reason
that enables these loops is that the server executing the discovery
algorithm is seriously misconfigured in that it does not recognise
the request as one that is to be processed by itself. RADIUS has no
built-in loop detection, so any such loops would remain undetected.
So, if step 18 of the algorithm discovers such a possible-loop
situation, the algorithm should be aborted and an error logged.
After executing the above algorithm, the RADIUS server establishes a After executing the above algorithm, the RADIUS server establishes a
connection to a home server from the result set. This connection can connection to a home server from the result set. This connection can
potentially remain open for an indefinite amount of time. This potentially remain open for an indefinite amount of time. This
conflicts with the possibility of changing device and network conflicts with the possibility of changing device and network
configurations on the receiving end. Typically, TTL values for configurations on the receiving end. Typically, TTL values for
records in the name resolution system are used to indicate how long records in the name resolution system are used to indicate how long
it is safe to rely on the results of the name resolution. When a it is safe to rely on the results of the name resolution. If these
connection is open and the smallest of the TTL values which were used TTLs are very low, thrashing of connections becomes possible; the
for discovering the server has not expired, subsequent new user Effective TTL mitigates that risk. When a connection is open and the
sessions for the realm which corresponds to that open connection smallest of the Effective TTL value which was learned during
SHOULD re-use the existing connection and SHOULD NOT re-execute the discovering the server has not expired, subsequent new user sessions
dynamic discovery algorithm nor open a new connection. To allow for for the realm which corresponds to that open connection SHOULD re-use
a change of configuration, a RADIUS server SHOULD re-execute the the existing connection and SHOULD NOT re-execute the dynamic
dynamic discovery algorithm after the lowest of the TTL values that discovery algorithm nor open a new connection. To allow for a change
are associated with this connection have expired. The server MAY of configuration, a RADIUS server SHOULD re-execute the dynamic
keep the session open during this re-assessment to avoid closure and discovery algorithm after the Effective TTL that is associated with
immediate re-opening of the connection should the result not have this connection has expired. The server MAY keep the session open
changed. during this re-assessment to avoid closure and immediate re-opening
of the connection should the result not have changed.
Should the algorithm above terminate with an empty set (but no
error), the RADIUS server SHOULD NOT attempt another execution of
this algorithm for the same target realm before the negative TTL has
expired.
Should the algorithm above terminate due to an error with no TTL Should the algorithm above terminate with O-1 = empty set, the RADIUS
value known (e.g. DNS SERVFAIL), the RADIUS server SHOULD NOT server SHOULD NOT attempt another execution of this algorithm for the
attempt another execution of this algorithm for the same target realm same target realm before the timeout O-2 has passed.
before a configurable timeout interval has passed.
2.3.5. Delay considerations 3.4.5. Delay considerations
The host's name resolution library may need to contact outside The host's name resolution library may need to contact outside
entities to perform the name resolution (e.g. authoritative name entities to perform the name resolution (e.g. authoritative name
servers for a domain), and since the NAI discovery algorithm is based servers for a domain), and since the NAI discovery algorithm is based
on uncontrollable user input, the destination of the lookups is out on uncontrollable user input, the destination of the lookups is out
of control of the server that performs NAI discovery. If such of control of the server that performs NAI discovery. If such
outside entities are misconfigured or unreachable, the algorithm outside entities are misconfigured or unreachable, the algorithm
above may need an unacceptably long time to terminate. Many RADIUS above may need an unacceptably long time to terminate. Many RADIUS
implementations time out after five seconds of delay between Request implementations time out after five seconds of delay between Request
and Response. It is not useful to wait until the host name and Response. It is not useful to wait until the host name
resolution library signals a time-out of its name resolution resolution library signals a time-out of its name resolution
algorithms; instead, implementations of NAI discovery SHOULD algorithms. The algorithm therefore control execution time with
terminate the algorithm after the fixed upper bound of time of three TIMER. Execution of the NAI discovery algorithm SHOULD be non-
seconds. If no final output of the algorithm is available after this blocking (i.e. allow other requests to be processed in parallel to
timeout, the RADIUS server MUST assume the empty set as a result and the execution of the algorithm).
treat the pending request according to its static configuration
(e.g., fallback to a default route to a home server). Execution of
the NAI discovery algorithm SHOULD be non-blocking (i.e. allow other
requests to be processed in parallel to the execution of the
algorithm).
2.3.6. Example 3.4.6. Example
Example: Assume Assume
a user from the Technical University of Munich, Germany, has a a user from the Technical University of Munich, Germany, has a
RADIUS User-Name of "foobar@tu-m[U+00FC]nchen.example". RADIUS User-Name of "foobar@tu-m[U+00FC]nchen.example".
The name resolution library on the RADIUS forwarding server does The name resolution library on the RADIUS forwarding server does
not have the realm tu-m[U+00FC]nchen.example in its forwarding not have the realm tu-m[U+00FC]nchen.example in its forwarding
configuration, but uses DNS for name resolution and has configured configuration, but uses DNS for name resolution and has configured
the use of Dynamic Discovery to discover RADIUS servers. the use of Dynamic Discovery to discover RADIUS servers.
It is IPv6-enabled and prefers AAAA records over A records. It is IPv6-enabled and prefers AAAA records over A records.
It is listening for incoming RADIUS/TLS requests on 192.37.5.1, It is listening for incoming RADIUS/TLS requests on 192.0.2.1, TCP
TCP/2083. /2083.
May the configuration variables be
DNS_TIMEOUT = 3 seconds
MIN_EFF_TTL = 60 seconds
BACKOFF_TIME = 3600 seconds
If DNS contains the following records: If DNS contains the following records:
xn--tu-mnchen-t9a.example. IN NAPTR 50 50 "s" xn--tu-mnchen-t9a.example. IN NAPTR 50 50 "s"
"aaa+auth:radius.tls" "" _radiustls._tcp.xn--tu-mnchen- "aaa+auth:radius.tls" "" _myradius._tcp.xn--tu-mnchen-t9a.example.
t9a.example.
xn--tu-mnchen-t9a.example. IN NAPTR 50 50 "s" xn--tu-mnchen-t9a.example. IN NAPTR 50 50 "s"
"fooservice:bar.dccp" "" _abc._def.xn--tu-mnchen-t9a.example. "fooservice:bar.dccp" "" _abc123._def.xn--tu-mnchen-t9a.example.
_radiustls._tcp.xn--tu-mnchen-t9a.example. IN SRV 0 10 2083 _myradius._tcp.xn--tu-mnchen-t9a.example. IN SRV 0 10 2083
radsec.xn--tu-mnchen-t9a.example. radsecserver.xn--tu-mnchen-t9a.example.
_radiustls._tcp.xn--tu-mnchen-t9a.example. IN SRV 0 20 2083 _myradius._tcp.xn--tu-mnchen-t9a.example. IN SRV 0 20 2083
backup.xn--tu-mnchen-t9a.example. backupserver.xn--tu-mnchen-t9a.example.
radsec.xn--tu-mnchen-t9a.example. IN AAAA radsecserver.xn--tu-mnchen-t9a.example. IN AAAA
2001:0DB8::202:44ff:fe0a:f704 2001:0DB8::202:44ff:fe0a:f704
radsec.xn--tu-mnchen-t9a.example. IN A 192.0.2.3 radsecserver.xn--tu-mnchen-t9a.example. IN A 192.0.2.3
backup.xn--tu-mnchen-t9a.example. IN A 192.0.2.7 backupserver.xn--tu-mnchen-t9a.example. IN A 192.0.2.7
Then the algorithm executes as follows, with I = Then the algorithm executes as follows, with I =
"foobar@tu-m[U+00FC]nchen.example", and no consortium name mangling "foobar@tu-m[U+00FC]nchen.example", and no consortium name mangling
in use: in use:
1. P = 7 1. P = 7
2. R = "tu-m[U+00FC]nchen.example" 2. R = "tu-m[U+00FC]nchen.example"
3. NOOP 3. NOOP
4. [name resolution library converts R to xn--tu-mnchen- 4. name resolution library converts R to xn--tu-mnchen-t9a.example
t9a.example] Query result: ( 50 50 "s" "aaa+auth:radius.tls" ""
_radiustls._tcp.xn--tu-mnchen-t9a.example. ; 50 50 "s"
"fooservice:bar.dccp" "" _abc._def.xn--tu-mnchen-t9a.example. )
5. Result: 50 50 "s" "aaa+auth:radius.tls" "" _radiustls._tcp.xn 5. TIMER starts.
--tu-mnchen-t9a.example.
6. NOOP 6. Result:
7. O' = {(radsec.xn--tu-mnchen-t9a.example.; 2083; 10; TTL (TTL = 47) 50 50 "s" "aaa+auth:radius.tls" ""
A),(backup.xn--tu-mnchen-t9a. example.;2083; 20; TTL B)} _myradius._tcp.xn--tu-mnchen-t9a.example.
8. Go to step 15. (TTL = 522) 50 50 "s" "fooservice:bar.dccp" ""
_abc123._def.xn--tu-mnchen-t9a.example.
9. (not executed) 7. Result:
10. (not executed) (TTL = 47) 50 50 "s" "aaa+auth:radius.tls" ""
_myradius._tcp.xn--tu-mnchen-t9a.example.
11. (not executed) 8. NOOP
9. Successive resolution performs SRV query for label
_myradius._tcp.xn--tu-mnchen-t9a.example, which results in
12. (not executed) (TTL 499) 0 10 2083 radsec.xn--tu-mnchen-t9a.example.
(TTL 2200) 0 20 2083 backup.xn--tu-mnchen-t9a.example.
10. NOOP
11. O' = {
(radsec.xn--tu-mnchen-t9a.example.; 2083; 10; 60),
(backup.xn--tu-mnchen-t9a.example.; 2083; 20; 60)
} // minimum TTL is 47, up'ed to MIN_EFF_TTL
12. Continuing at 18.
13. (not executed) 13. (not executed)
14. O = {(2001:0DB8::202:44ff:fe0a:f704; 2083; 10; TTL 14. (not executed)
A),(192.0.2.7; 2083; 20; TTL B)}
15. O = {(2001:0DB8::202:44ff:fe0a:f704; 2083; 10; TTL 15. (not executed)
A),(192.0.2.7; 2083; 20; TTL B)}. Terminate.
16. (not executed)
17. (not executed)
18. O-1 = {
(2001:0DB8::202:44ff:fe0a:f704; 2083; 10; 60),
(192.0.2.7; 2083; 20; 60)
}; O-2 = 0
19. No match with own listening address; terminate with tuple (O-1,
O-2) from previous step.
The implementation will then attempt to connect to two servers, with The implementation will then attempt to connect to two servers, with
preference to radsec.xn--tu-mnchen-t9a.example.:2083, using either preference to [2001:0DB8::202:44ff:fe0a:f704]:2083.
the AAAA or A addresses depending on the host configuration and its
IP stack's capabilities.
3. Security Considerations 4. Security Considerations
When using DNS without DNSSEC security extensions, the replies to The results from the execution of this algorithm are only trustworthy
NAPTR, SRV and A/AAAA requests as described in section Section 2 can if each of the lookup steps by the name resolution library were
not be trusted. RADIUS transports have an out-of-DNS-band means to cryptographically secured; i.e. if DNSSEC validation was turned on
verify that the discovery attempt led to the intended target: during the resolution AND all of the records were in a DNSSEC signed
certificate verification or TLS-PSK keys. zone AND validation of all those records was successful.
4. IANA Considerations When using DNS without DNSSEC security extensions for at least one of
the replies to NAPTR, SRV and A/AAAA requests as described in section
Section 3, the result O can not be trusted. Even if it can be
trusted (i.e. DNSSEC is in use), actual authorization of the
discovered server to provide service for the given realm needs to be
verified. A mechanism from section Section 2.1.1.3 or equivalent
MUST be used to verify authorization.
The algorithm has a configurable completion time-out DNS_TIMEOUT
defaulting to three seconds for RADIUS' operational reasons. The
lookup of DNS resource records based on unverified user input is an
attack vector for DoS attacks: an attacker might intentionally craft
bogus DNS zones which take a very long time to reply (e.g. due to a
particularly byzantine tree structure, or artificial delays in
responses).
To mitigate this DoS vector, implementations SHOULD consider rate-
limiting either their amount of new executions of the dynamic
discovery algorithm as a whole, or the amount of intermediate
responses to track, or at least the number of pending DNS queries.
Implementations MAY choose lower values than the default for
DNS_TIMEOUT to limit the impact of DoS attacks via that vector. They
MAY also continue their attempt to resolve DNS records even after
DNS_TIMEOUT has passed; a subsequent request for the same realm might
benefit from retrieving the results anyway. The amount of time to
spent waiting for a result will influence the impact of a possible
DoS attack; the waiting time value is implementation dependent and
outside the scope of this specification.
5. IANA Considerations
This document requests IANA registration of the following entries in This document requests IANA registration of the following entries in
existing registries: existing registries:
o S-NAPTR Application Service Tags registry o S-NAPTR Application Service Tags registry
* aaa+auth * aaa+auth
* aaa+acct
* aaa+acct
* aaa+dynauth * aaa+dynauth
o S-NAPTR Application Protocol Tags registry o S-NAPTR Application Protocol Tags registry
* radius.tls * radius.tls
* radius.dtls * radius.dtls
This document reserves the use of the "_radiustls" and "_radiusdtls" This document reserves the use of the "_radiustls" and "_radiusdtls"
Service labels. Service labels.
This document requests the creation of a new IANA registry named This document requests the creation of a new IANA registry named
"RADIUS/TLS SRV Protocol Registry" with the following initial "RADIUS/TLS SRV Protocol Registry" with the following initial
entries: entries:
o _tcp o _tcp
o _udp o _udp
5. Normative References 6. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782,
February 2000.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", RFC "Remote Authentication Dial In User Service (RADIUS)", RFC
2865, June 2000. 2865, June 2000.
[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000. [RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
[RFC3958] Daigle, L. and A. Newton, "Domain-Based Application [RFC3958] Daigle, L. and A. Newton, "Domain-Based Application
Service Location Using SRV RRs and the Dynamic Delegation Service Location Using SRV RRs and the Dynamic Delegation
Discovery Service (DDDS)", RFC 3958, January 2005. Discovery Service (DDDS)", RFC 3958, January 2005.
[RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B. [RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 5176, Authentication Dial In User Service (RADIUS)", RFC 5176,
January 2008. January 2008.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[RFC5580] Tschofenig, H., Adrangi, F., Jones, M., Lior, A., and B. [RFC5580] Tschofenig, H., Adrangi, F., Jones, M., Lior, A., and B.
Aboba, "Carrying Location Objects in RADIUS and Diameter", Aboba, "Carrying Location Objects in RADIUS and Diameter",
RFC 5580, August 2009. RFC 5580, August 2009.
[RFC5891] Klensin, J., "Internationalized Domain Names in [RFC5891] Klensin, J., "Internationalized Domain Names in
Applications (IDNA): Protocol", RFC 5891, August 2010. Applications (IDNA): Protocol", RFC 5891, August 2010.
[I-D.ietf-radext-dtls] [I-D.ietf-radext-dtls]
DeKok, A., "DTLS as a Transport Layer for RADIUS", draft- DeKok, A., "DTLS as a Transport Layer for RADIUS", draft-
ietf-radext-dtls-02 (work in progress), July 2012. ietf-radext-dtls-05 (work in progress), April 2013.
[RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga, [RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga,
"Transport Layer Security (TLS) Encryption for RADIUS", "Transport Layer Security (TLS) Encryption for RADIUS",
RFC 6614, May 2012. RFC 6614, May 2012.
[I-D.ietf-radext-nai]
DeKok, A., "The Network Access Identifier", draft-ietf-
radext-nai-03 (work in progress), May 2013.
Appendix A. Appendix A: ASN.1 Syntax of NAIRealm
PKIXServiceNameSAN93 {iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-dns-srv-name-93(40) }
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
IMPORTS
id-pkix
FROM PKIX1Explicit88 { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-explicit(18) } ;
-- from RFC 5280
-- In the GeneralName definition using the 1993 ASN.1 syntax
-- includes:
OTHER-NAME ::= TYPE-IDENTIFIER
-- Service Name Object Identifier
id-on OBJECT IDENTIFIER ::= { id-pkix 8 }
id-on-nai OBJECT IDENTIFIER ::= { id-on XXX }
-- Service Name
naiRealm OTHER-NAME ::= { NAIRealm IDENTIFIED BY { id-on-nai }}
NAIRealm ::= UTF8String (SIZE (1..MAX))
END
Authors' Addresses Authors' Addresses
Stefan Winter Stefan Winter
Fondation RESTENA Fondation RESTENA
6, rue Richard Coudenhove-Kalergi 6, rue Richard Coudenhove-Kalergi
Luxembourg 1359 Luxembourg 1359
LUXEMBOURG LUXEMBOURG
Phone: +352 424409 1 Phone: +352 424409 1
Fax: +352 422473 Fax: +352 422473
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