draft-ietf-radext-dynamic-discovery-00.txt   draft-ietf-radext-dynamic-discovery-01.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: January 3, 2010 OSC Expires: January 14, 2010 OSC
July 02, 2009 July 13, 2009
NAI-based Dynamic Peer Discovery for RADIUS over TLS and DTLS NAI-based Dynamic Peer Discovery for RADIUS over TLS and DTLS
draft-ietf-radext-dynamic-discovery-00 draft-ietf-radext-dynamic-discovery-01
Status of This Memo Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. This document may contain material provisions of BCP 78 and BCP 79.
from IETF Documents or IETF Contributions published or made publicly
available before November 10, 2008. The person(s) controlling the
copyright in some of this material may not have granted the IETF
Trust the right to allow modifications of such material outside the
IETF Standards Process. Without obtaining an adequate license from
the person(s) controlling the copyright in such materials, this
document may not be modified outside the IETF Standards Process, and
derivative works of it may not be created outside the IETF Standards
Process, except to format it for publication as an RFC or to
translate it into languages other than English.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on January 3, 2010. This Internet-Draft will expire on January 14, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 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 in effect on the date of Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 2, line 23 skipping to change at page 2, line 12
This document specifies a means to find authoritative AAA servers for This document specifies a means to find authoritative AAA servers for
a given NAI realm as defined in [RFC4282]. It can be used in a given NAI realm as defined in [RFC4282]. It can be used in
conjunction with RADIUS over TLS and RADIUS over DTLS. conjunction with RADIUS over TLS and RADIUS over DTLS.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
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. DNS-based NAPTR/SRV Peer Discovery . . . . . . . . . . . . . . 3
2.1. DNS RR definition . . . . . . . . . . . . . . . . . . . . . 3 2.1. Applicability . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Realm to AAA server resolution algorithm . . . . . . . . . 4 2.2. DNS RR definition . . . . . . . . . . . . . . . . . . . . . 3
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 2.3. Realm to AAA server resolution algorithm . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
5. Normative References . . . . . . . . . . . . . . . . . . . . . 7 5. Normative References . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
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]
skipping to change at page 3, line 26 skipping to change at page 3, line 26
RadSec node: a RadSec client or server RadSec node: a RadSec client or server
RadSec Client: a RadSec instance which initiates a new connection. RadSec Client: a RadSec instance which initiates a new connection.
RadSec Server: a RadSec instance which listens on a RadSec port and RadSec Server: a RadSec instance which listens on a RadSec port and
accepts new connections accepts new connections
2. DNS-based NAPTR/SRV Peer Discovery 2. DNS-based NAPTR/SRV Peer Discovery
2.1. DNS RR definition 2.1. Applicability
Dynamic server discovery as defined in this document is only
applicable for AAA transactions where a AAA server receives a request
with a NAI realm for which no home AAA server is known. I.e. where
static server configuration does not contain a known home
authentication server, or where the server configuration explicitly
states that the realm destination is to be looked up dynamically.
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, Access-Accepts, Accounting
Messages or Change-of-Authorisation messages use the previously-
established communication channel between client and server.
2.2. DNS RR definition
DNS definitions of RadSec servers can be either NAPTR records or SRV DNS definitions of RadSec servers can be either NAPTR records or SRV
records. When both are defined, the resolution algorithm prefers records. When both are defined, the resolution algorithm prefers
NAPTR results (see section Section 2.2 below). The NAPTR service NAPTR results (see section Section 2.3 below). The NAPTR service
field used is "AAAS+RADSECT". The SRV prefix used is "_radsec._tcp". field used is "AAAS+RADSECT". The SRV prefix used is "_radsec._tcp".
It is expected that in most cases, the label used for the records is It is expected that in most cases, the label used for the records is
the DNS representation (punycode) of the literal realm name for which the DNS representation (punycode) of the literal realm name for which
the server is the AAA server. the server is the AAA server.
However, arbitrary other labels may be used if, for example, a However, arbitrary other labels may be used if, for example, a
roaming consortium uses realm names which are not associated to DNS roaming consortium uses realm names which are not associated to DNS
names or special-purpose consortia where a globally valid discovery names or special-purpose consortia where a globally valid discovery
is not a use case. Such other labels require a consortium-wide is not a use case. Such other labels require a consortium-wide
agreement about the transformation from realm name to lookup label. agreement about the transformation from realm name to lookup label.
skipping to change at page 4, line 41 skipping to change at page 5, line 8
restena.lu. IN NAPTR 50 50 "a" "AAAS+RADSECT" "" aaa- restena.lu. IN NAPTR 50 50 "a" "AAAS+RADSECT" "" aaa-
default.restena.lu default.restena.lu
_radsec._tcp.eduroam.restena.lu. IN SRV 0 10 2083 aaa- _radsec._tcp.eduroam.restena.lu. IN SRV 0 10 2083 aaa-
eduroam.restena.lu. eduroam.restena.lu.
_radsec._tcp.restena.lu. IN SRV 0 10 2083 aaa- _radsec._tcp.restena.lu. IN SRV 0 10 2083 aaa-
default.restena.lu. default.restena.lu.
2.2. Realm to AAA server resolution algorithm 2.3. Realm to AAA server resolution algorithm
Input I to the algorithm is a User-Name in the form of a NAI as Input I to the algorithm is a User-Name in the form of a NAI as
defined in [RFC4282] as extracted from the User-Name attribute in an defined in [RFC4282] as extracted from the User-Name attribute in an
Access-Request. Output O of the algorithm is a set of hostname:port Access-Request. Output O of the algorithm is a set of hostname:port
and an assoiciated order/preference; the set can be empty. The and an assoiciated order/preference; the set can be empty.
algorithm to determine the AAA server to contact is as follows:
Note well: The attribute User-Name does not necessarily contain well-
formed NAIs and may not even contain well-formed UTF-8 strings. This
document describes server discovery only for well-formed NAIs in
UTF-8 encoding. The result of all other possible contents of User-
Name is unspecified; this includes, but is not limited to:
Usage of separators other than @
Usage of multiple @ separators
Encoding of User-Name in local encodings
The algorithm to determine the AAA server to contact is as follows:
1. Determine P = (position of first "@" character) in I. 1. Determine P = (position of first "@" 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
4. Generate R' = ( DNS library transformation of R to an FQDN in 3. Optional: modify R according to agreed consortium procedures
punycode)
5. If generation of R' failed, O = {}; terminate. 4. Using the host's name resolution library, perform a NAPTR query
for service "AAAS+RADSECT" for R
6. Perform NAPTR query for service "AAAS+RADSECT" with R as label 5. If name resolution returns with error, O = { }. Terminate.
7. If no result, continue at step 10. 6. If no result, continue at step 9.
8. Evaluate NAPTR result, perform subsequent lookup steps until 7. Evaluate NAPTR result, perform subsequent lookup steps until
lookup yields one or more hostnames. O = (set of {Order/ lookup yields one or more hostnames. O = (set of {Order/
Preference, hostname:port} for all lookup results). Preference, hostname:port} for all lookup results).
9. Terminate. 8. Terminate.
10. Generate R'' = (prefix R' with "_radsec._tcp.") 9. Generate R' = (prefix R with "_radsec._tcp.")
11. Perform SRV lookup with R'' as label. If no result, O = {}; 10. Using the host's name resolution library, perform SRV lookup
terminate. with R' as label.
12. Perform subsequent lookup steps until lookup yields one or more 11. If name resolution returns with error, O = { }. Terminate.
12. If no result, O = {}; terminate.
13. Perform subsequent lookup steps until lookup yields one or more
hostnames. O = (set of {Order/Preference, hostname} for all hostnames. O = (set of {Order/Preference, hostname} for all
hostnames). Terminate. hostnames). Terminate.
Example: Assume a user from the Technical University of Munich, Example: Assume a user from the Technical University of Munich,
Germany, has a RADIUS User-Name of Germany, has a RADIUS User-Name of
"foobar@tu-m[U+00FC]nchen.example". If DNS contains the following "foobar@tu-m[U+00FC]nchen.example". If DNS contains the following
records: records:
xn--tu-mnchen-t9a.example. IN NAPTR 50 50 "s" "AAAS+RADSECT" "" xn--tu-mnchen-t9a.example. IN NAPTR 50 50 "s" "AAAS+RADSECT" ""
_radsec._tcp.xn--tu-mnchen-t9a.example. _radsec._tcp.xn--tu-mnchen-t9a.example.
skipping to change at page 6, line 13 skipping to change at page 6, line 44
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. R' = "xn--tu-mnchen-t9a.example." 4. Query result: ( 0 10 2083 radsec.xn--tu-mnchen-t9a.example. ; 0
20 2083 backup.xn--tu-mnchen-t9a.example. )
5. NOOP 5. NOOP
6. Query result: ( 0 10 2083 radsec.xn--tu-mnchen-t9a.example. ; 0 6. NOOP
20 2083 backup.xn--tu-mnchen-t9a.example. )
7. NOOP
8. O = {(10,radsec.xn--tu-mnchen-t9a.example.:2083),(20,backup.xn-- 7. O = {(10,radsec.xn--tu-mnchen-t9a.example.:2083),(20,backup.xn--
tu-mnchen-t9a.example.:2083)} tu-mnchen-t9a.example.:2083)}
8. Terminate.
9. Terminate. 9. (not executed)
10. (not executed) 10. (not executed)
11. (not executed) 11. (not executed)
12. (not executed) 12. (not executed)
13. (not executed)
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 radsec.xn--tu-mnchen-t9a.example.:2083, using either
the AAAA or A addresses depending on the host configuration and its the AAAA or A addresses depending on the host configuration and its
IP stack's capabilities. IP stack's capabilities.
3. Security Considerations 3. Security Considerations
When using DNS without security, the replies to NAPTR, SRV and A/AAAA When using DNS without security, the replies to NAPTR, SRV and A/AAAA
requests as described in section Section 2 can not be trusted. requests as described in section Section 2 can not be trusted.
RADIUS transports have an out-of-DNS-band means to verify that the RADIUS transports have an out-of-DNS-band means to verify that the
 End of changes. 26 change blocks. 
43 lines changed or deleted 65 lines changed or added

This html diff was produced by rfcdiff 1.35. The latest version is available from http://tools.ietf.org/tools/rfcdiff/