INTERNET DRAFT Pat R. Calhoun
Category: Standards Track Sun Microsystems, Inc.
Title: draft-calhoun-diameter-nasreq-05.txt William Bulley
Date: September 2000 Merit Network, Inc.
Allan C. Rubens
Tut Systems, Inc.
Jeff Haag
Cisco Systems
DIAMETER NASREQ Extensions
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
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The list of current Internet-Drafts can be accessed at:
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This document is an individual contribution for consideration by the
AAA Working Group of the Internet Engineering Task Force. Comments
should be submitted to the diameter@diameter.org mailing list.
Distribution of this memo is unlimited.
Copyright (C) The Internet Society 1999. All Rights Reserved.
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Abstract
This document describes the DIAMETER extension that is used for AAA
in a PPP/SLIP Dial-Up and Terminal Server Access environment. This
extension, combined with the base protocol, satisfies the
requirements defined in the NASREQ AAA criteria specification and the
ROAMOPS AAA Criteria specification.
Given that it is expected that initial deployments of the DIAMETER
protocol in a dial-up environment will include legacy systems, this
extension was carefully designed to ease the burden of servers that
must perform protocol conversion between RADIUS and DIAMETER. This
is achieved by re-using the RADIUS address space, eliminating the
need to perform attribute lookups.
Table of Contents
1.0 Introduction
1.1 Requirements language
2.0 Supported AVPs
2.1 DIAMETER AVPs
2.1.1 Request-Type AVP
2.1.2 Filter-Rule AVP
2.2 Legacy RADIUS Attributes
2.2.1 NAS-IP-Address AVP
2.2.2 NAS-Identifier AVP
2.2.3 State AVP
2.2.4 Class AVP
3.0 Legacy PPP Authentication Support
3.1 Command-Codes Values
3.1.1 AA-Request (AAR) Command
3.1.1.1 User-Password AVP
3.1.1.2 CHAP-Password AVP
3.1.1.3 CHAP-Challenge AVP
3.1.2 AA-Answer (AAA) Command
3.1.3 AA-Challenge-Ind (ACI) Command
3.2 Reply-Message AVP
4.0 Extensible Authentication Protocol Support
4.1 Alternative Uses
4.2 Command-Codes Values
4.2.1 DIAMETER-EAP-Request (DER) Command
4.2.2 DIAMETER-EAP-Answer (DEA) Command
4.2.3 DIAMETER-EAP-Ind (DEI) Command
4.3 EAP-Payload AVP
5.0 DIAMETER Session Termination
6.0 Legacy Authorization AVPs
6.1 Service Identification AVPs
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6.1.1 NAS-Port AVP
6.1.2 Service-Type AVP
6.1.3 Filter-Id AVP
6.1.4 Callback-Number AVP
6.1.5 Callback-Id AVP
6.1.6 Idle-Timeout AVP
6.1.7 Called-Station-Id AVP
6.1.8 Calling-Station-Id AVP
6.1.9 NAS-Port-Type AVP
6.1.10 Port-Limit AVP
6.1.11 Filter-Rule AVP
6.2 Framed Access Authorization AVPs
6.2.1 Framed-Protocol AVP
6.2.2 Framed-IP-Address AVP
6.2.3 Framed-IP-Netmask AVP
6.2.4 Framed-Routing AVP
6.2.5 Framed-MTU AVP
6.2.6 Framed-Compression AVP
6.2.7 Framed-IP-Route AVP
6.2.8 Framed-IPX-Network AVP
6.2.9 Framed-AppleTalk-Link AVP
6.2.10 Framed-AppleTalk-Network AVP
6.2.11 Framed-AppleTalk-Zone AVP
6.3 Non-Framed Access Authorization AVPs
6.3.1 Login-IP-Host AVP
6.3.2 Login-Service AVP
6.3.3 Login-TCP-Port AVP
6.3.4 Login-LAT-Service AVP
6.3.5 Login-LAT-Node AVP
6.3.6 Login-LAT-Group AVP
6.3.7 Login-LAT-Port AVP
6.4 Tunneling AVPs
6.4.1 Tunnel-Type AVP
6.4.2 Tunnel-Medium-Type AVP
6.4.3 Tunnel-Client-Endpoint AVP
6.4.4 Tunnel-Server-Endpoint AVP
6.4.5 Tunnel-Password AVP
6.4.6 Tunnel-Private-Group-ID AVP
6.4.7 Tunnel-Assignment-ID AVP
6.4.8 Tunnel-Preference AVP
6.4.9 Tunnel-Client-Auth-ID AVP
6.4.10 Tunnel-Server-Auth-ID AVP
7.0 Interactions with Resource Management
8.0 IANA Considerations
8.1 Request-Type AVP Values
9.0 Security Considerations
10.0 References
11.0 Acknowledgements
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12.0 Authors' Addresses
13.0 Full Copyright Statement
1.0 Introduction
This document describes the DIAMETER extension that is used for AAA
in a PPP/SLIP Dial-Up and Terminal Server Access environment. This
extension, combined with the base protocol [2], satisfies the
requirements defined in the NASREQ AAA criteria specification [24]
and the ROAMOPS AAA Criteria specification [4].
This document is divided into three main sections. The first section
defines the DIAMETER Command-Codes and AVPs that are needed to
support legacy PPP authentication protocols, those that are typically
supported by RADIUS [1] servers. The second section defines the
Command-Codes and AVPs necessary for a DIAMETER node to support PPP's
Extensible Authentication Protocol (EAP) [25]. The third section
contains the Authorization AVPs that are needed for the various
services offered by a NAS, such as PPP dial-in, terminal server and
tunneling applications, such as L2TP [16].
Given that it is expected that initial deployments of the DIAMETER
protocol in a dial-up environment will include legacy systems, this
extension was carefully designed to ease the burden of servers that
must perform protocol conversion between RADIUS and DIAMETER. This
is achieved by re-using the RADIUS address space, eliminating the
need to perform attribute lookups.
The value assigned for the Extension-Id [2] AVP is one (1).
1.1 Requirements language
In this document, the key words "MAY", "MUST, "MUST NOT", "optional",
"recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as
described in [12].
2.0 Supported AVPs
This section lists all of the DIAMETER AVPs and the legacy RADIUS
attributes supported by this extension.
2.1 DIAMETER AVPs
This section will define all of the AVPs that are not backward
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compatible with the RADIUS protocol [1]. A DIAMETER message that
includes one of these AVPs MAY cause interoperability issues should
the request traverse a AAA node that only supports the RADIUS
protocol. However, the DIAMETER protocol SHOULD NOT be hampered from
future developments due to the existing installed base.
The following table describes the DIAMETER AVPs defined in the NASREQ
extension, their AVP Code values, types, possible flag values and
whether the AVP MAY be encrypted.
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section Value | | |SHLD| MUST|MAY |
Attribute Name Code Defined Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----+
Filter-Rule 400 2.1.2 String | M | P | | V | Y |
Request-Type 401 2.1.1 Integer32| M | P | | V | N |
EAP-Payload 402 4.2 Data | M | P | | V | Y |
2.1.1 Request-Type AVP
The Request-Type AVP (AVP Code 401) is of type Integer32 and is used
to determine the type of request being transmitted. Note that a
request with this AVP set to a value other than
AUTHORIZE_AUTHENTICATE MAY break backward RADIUS compatibility. The
following values are defined:
AUTHENTICATE_ONLY 1
The request being sent is for authentication only, and MUST
contain the relevant authentication AVPs that are needed by the
DIAMETER server to authenticate the user.
AUTHORIZE_ONLY 2
The request being sent is for authorization only, and MUST
contain the authorization AVPs that are necessary to identify
the service being requested/offered.
AUTHORIZE_AUTHENTICATE 3
The request contains a request for both authentication and
authorization. The request MUST include both the relevant
authentication information, and authorization information
necessary to identify the service being requested/offered.
2.1.2 Filter-Rule AVP
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The Filter-Rule AVP (AVP Code 400) is of type String and provides
filter rules that need to be configured on the NAS for the user. One
or more such AVPs MAY be present in an authorization response.
The String field MUST contain a filter rule in the following format:
"permit (offset=value AND offset=value) OR offset=value" or "deny
(offset=value AND offset=value) OR offset=value". The keyword
"permit" means that the filter will allow any traffic that matches
the rule, while deny will not allow the traffic to be routed. The
filter rules can also use the keywords "AND" and "OR", for which no
additional explanation is necessary. The braces "(" and ")" can be
used to setup grouping of expressions.
2.2 Legacy RADIUS Attributes
The DIAMETER protocol reserves the first 255 AVP identifiers for
"legacy RADIUS" support, and SHOULD only used when a DIAMETER/RADIUS
gateway function is invoked. The following table contains the RADIUS
attributes supported by this DIAMETER extension, their AVP code
values, types, possible flag values and whether the AVP MAY be
encrypted.
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section Value | | |SHLD| MUST|MAY |
Attribute Name Code Defined Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----+
User-Password 2 3.1.1.1 Data | M | P | | V | Y |
CHAP-Password 3 3.1.1.2 Data | M | P | | V | Y |
NAS-IP-Address 4 2.2.1 Address | M | P | | V | Y |
NAS-Port 5 6.1.1 Integer32| M | P | | V | Y |
Service-Type 6 6.1.2 Integer32| M | P | | V | Y |
Framed-Protocol 7 6.2.1 Integer32| M | P | | V | Y |
Framed-IP-Address 8 6.2.2 Address | M | P | | V | Y |
Framed-IP-Netmask 9 6.2.3 Address | M | P | | V | Y |
Framed-Routing 10 6.2.4 Integer32| M | P | | V | Y |
Filter-Id 11 6.1.3 String | M | P | | V | Y |
Framed-MTU 12 6.2.5 Integer32| M | P | | V | Y |
Framed- 13 6.2.6 Integer32| M | P | | V | Y |
Compression | | | | | |
Login-IP-Host 14 6.3.1 Address | M | P | | V | Y |
Login-Service 15 6.3.2 Integer32| M | P | | V | Y |
Login-TCP-Port 16 6.3.3 Integer32| M | P | | V | Y |
Reply-Message 18 3.2 String | M | P | | V | Y |
Callback-Number 19 6.1.4 String | M | P | | V | Y |
Callback-Id 20 6.1.5 String | M | P | | V | Y |
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Framed-IP-Route 22 6.2.7 String | M | P | | V | Y |
Framed-IPX-Route 23 6.2.8 String | M | P | | V | Y |
State 24 2.2.3 Data | M | P | | V | Y |
Class 25 2.2.4 Data | M | P | | V | Y |
Idle-Timeout 28 6.1.6 Integer32| M | P | | V | Y |
Called-Station-Id 30 6.1.7 String | M | P | | V | Y |
Calling-Station- 31 6.1.8 String | M | P | | V | Y |
Id | | | | | |
NAS-Identifier 32 2.2.2 String | M | P | | V | Y |
Login-LAT-Service 34 6.3.4 Integer32| M | P | | V | Y |
Login-LAT-Node 35 6.3.5 String | M | P | | V | Y |
Login-LAT-Group 36 6.3.6 Data | M | P | | V | Y |
Framed-Appletalk- 37 6.2.9 Integer32| M | P | | V | Y |
Link | | | | | |
Framed-Appletalk- 38 6.2.10 Integer32| M | P | | V | Y |
Network | | | | | |
Framed-Appletalk- 39 6.2.11 Data | M | P | | V | Y |
Zone | | | | | |
CHAP-Challenge 60 3.1.1.3 Data | M | P | | V | Y |
NAS-Port-Type 61 6.1.9 Integer32| M | P | | V | Y |
Port-Limit 62 6.1.10 Integer32| M | P | | V | Y |
Login-LAT-Port 63 6.3.7 String | M | P | | V | Y |
Tunnel-Type 64 6.4.1 Integer32| M | P | | V | Y |
Tunnel-Medium- 65 6.4.2 Integer32| M | P | | V | Y |
Type | | | | | |
Tunnel-Client- 66 6.4.3 String | M | P | | V | Y |
Endpoint | | | | | |
Tunnel-Server- 67 6.4.4 String | M | P | | V | Y |
Endpoint | | | | | |
Tunnel-Password 69 6.4.5 String | M | P | | V | Y |
Tunnel-Private- 81 6.4.6 String | M | P | | V | Y |
Group-ID | | | | | |
Tunnel- 82 6.4.7 String | M | P | | V | Y |
Assignment-Id | | | | | |
Tunnel-Preference 83 6.4.8 Integer32| M | P | | V | Y |
Tunnel-Client- 90 6.4.9 String | M | P | | V | Y |
Auth-ID | | | | | |
Tunnel-Server- 91 6.4.10 String | M | P | | V | Y |
Auth-ID | | | | | |
2.2.1 NAS-IP-Address AVP
The Host-IP-Address AVP (AVP Code 4) [1] is of type Address, and
contains the IP Address of the NAS providing service to the user.
When this AVP is present, the Host-Name AVP DOES NOT represent the
NAS providing service to the user. Note that this AVP SHOULD only
added by a RADIUS/DIAMETER protocol gateway [28].
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2.2.2 NAS-Identifier AVP
The NAS-Identifier AVP (AVP Code 32) [1] is of type String, and
contains the Identity of the NAS providing service to the user. When
this AVP is present, the Host-Name AVP DOES NOT represent the NAS
providing service to the user. Note that this AVP SHOULD only added
by a RADIUS/DIAMETER protocol gateway [28].
2.2.3 State AVP
The State AVP (AVP Code 24) is used to transmit the contents of the
RADIUS State attribute, and no interpretation of the contents should
be made. Note that this AVP SHOULD only added by a RADIUS/DIAMETER
protocol gateway [28].
2.2.4 Class AVP
The Class AVP (AVP Code 25) is used to transmit the contents of the
RADIUS Class attribute, and no interpretation of the contents should
be made. Note that this AVP SHOULD only added by a RADIUS/DIAMETER
protocol gateway [28].
3.0 Legacy PPP Authentication Support
This section defines the new Command-Code [2] values required to
support the legacy PPP authentication protocol (PAP, CHAP), as well
as the AVPs that are necessary to carry the authentication
information in the DIAMETER protocol. The functionality defined here
provides a RADIUS-like AAA service, over a more reliable and secure
transport, as defined in the base protocol [2].
Unlike the RADIUS protocol [1], the DIAMETER protocol does not
require authentication information to be contained in a request from
the client. Therefore, it is possible to send a request for
authorization only. The type of service depends upon the Request-Type
AVP. This difference MAY cause operational issues in environments
that need RADIUS interoperability, and it MAY be necessary that
protocol conversion gateways add some authentication information when
transmitting to a RADIUS server.
3.1 Command-Codes Values
This section defines new Command-Code [2] values that MUST be
supported by all DIAMETER implementations that conform to this
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specification. The following Command Codes are defined in this
section:
Command-Name Abbrev. Code Reference
--------------------------------------------------------
AA-Request AAR 265 3.1.1
AA-Answer AAA 266 3.1.2
AA-Challenge-Ind ACI 267 3.1.3
3.1.1 AA-Request (AAR) Command
The AA-Request message (AAR), indicated by the Command-Code field set
to 265, is used in order to request authentication and/or
authorization for a given PPP user. The type of request is identified
through the Request-Type AVP, and the default mode is both
authentication and authorization.
If Authentication is requested the User-Name attribute SHOULD be
present, as well as any additional authentication AVPs that would
carry the password information. A request for authorization only
SHOULD include the information from which the authorization will be
performed, such as the DNIS and ANI AVPs. Certain networks MAY use
different AVPs for authorization purposes. A request for
authorization will include some AVPs defined in sections 2.0 and 6.0.
It is possible for a single session to be authorized only first, then
followed by an authentication request. However, the inverse SHOULD
NOT be permitted.
If the AA-Request is a result of an AA-Challenge-Ind, the Session-Id
MUST be identical as the one provided in the initial AA-Request for
the same session. If the AA-Request is a result of an AA-Challenge-
Ind that included a State AVP, the same AVP MUST be present in the
following AA-Request.
Message Format
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<AA-Request> ::= <DIAMETER Header, Command-Code = 265>
<Session-Id AVP>
<Host-Name AVP>
[<Destination-NAI>]
[<NAS-IP-Address>]
[<NAS-Identifier>]
[<User-Name AVP>]
[<User-Password AVP> ||
<CHAP-Password AVP> &&
<CHAP-Challenge AVP>]
[<State AVP>]
[<Authorization AVPs>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Vector AVP>]
3.1.1.1 User-Password AVP
The User-Password AVP (AVP Code 2) is of type Data and contains the
password of the user to be authenticated, or the user's input
following an AA-Challenge-Ind.
This AVP MUST be encrypted using one of the methods described in [2]
or [13]. Unless this AVP is used for one-time passwords, the User-
Password AVP SHOULD NOT be used in non-trusted proxy environments.
The clear-text password (prior to encryption) MUST NOT be longer than
128 bytes in length.
3.1.1.2 CHAP-Password AVP
The CHAP-Password AVP (AVP Code 3) is of type Complex and contains
the response value provided by a PPP Challenge-Handshake
Authentication Protocol (CHAP) [6] user in response to the challenge.
If the CHAP-Password AVP is found in a message, the CHAP-Challenge
AVP (see section 3.1.1.3) MUST be present as well.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
AVP Header (AVP Code = 3)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CHAP Ident | Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The CHAP Ident field contains the one octet CHAP Identifier from the
user's CHAP response [6]. The Data field is 16 octets, and contains
the CHAP Response from the user. The actual computation of the CHAP
response can be found in [6].
3.1.1.3 CHAP-Challenge AVP
The CHAP-Challenge AVP (AVP Code 60) is of type Data and contains the
CHAP Challenge sent by the NAS to a PPP Challenge-Handshake
Authentication Protocol (CHAP) [6] user.
3.1.2 AA-Answer (AAA) Command
The AA-Answer (AAA) message, indicated by the Command-Code field set
to 266, is sent in response to the AA-Request message. If
authorization was requested, a successful response will include the
authorization AVPs appropriate for the service being provided, as
defined in section 2.0 and 6.0.
Message Format
<AA-Answer> ::= <DIAMETER Header, Command-Code = 266>
<Session-Id AVP>
<Result-Code AVP>
<Host-Name AVP>
<Destination-NAI>
[<User-Name AVP>]
[<Authorization AVPs>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Vector AVP>]
3.1.3 AA-Challenge-Ind (ACI) Command
The AA-Challenge-Ind (ACI) message, indicated by the Command-Code
field set to 267, is sent by a DIAMETER Home server to issue a
challenge requiring a response to a dial-up user. The message MAY
have one or more Reply-Message AVP, the User-Name AVP and it MAY have
zero or one State AVP. No other AVPs are permitted in an AA-
Challenge-Ind other than security related AVPs [2, 13].
On receipt of an AA-Challenge-Ind, the Identifier field is matched
with a pending AA-Request. Invalid messages are silently discarded.
The receipt of a valid AA-Challenge-Ind indicates that a new AA-
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Request SHOULD be sent. The NAS MAY display the text message, if any,
to the user, and then prompt the user for a response. It then sends
its original AA-Request with a new request ID, with the User-Password
AVP replaced by the user's response (encrypted), and including the
State AVP from the AA-Challenge-Ind, if any.
A NAS that supports PAP MAY forward the Reply-Message to the dial-in
client and accept a PAP response which it can use as though the user
had entered the response. If the NAS cannot do so, it should treat
the AA-Challenge-Ind as though it had received an AA-Answer with a
Result-Code AVP set to a value other than DIAMETER_SUCCESS instead.
When possible, authentication mechanisms that include more than a
single authentication round trip SHOULD use EAP (see section 4.0)
instead of the AA-Challenge-Ind. This command has been maintained for
RADIUS backward compatibility.
AA-Challenge-Ind ::= <DIAMETER Header, Command-Code = 267>
<Session-Id AVP>
<Result-Code AVP>
<Host-Name AVP>
<Destination-NAI>
[<User-Name AVP>]
[<State AVP>]
[<Reply-Message AVPs>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Vector AVP>]
3.2 Reply-Message AVP
The Reply-Message AVP (AVP Code 18) is of type String and contains
text which MAY be displayed to the user. When used in an AA-Answer
message with a successful Result-Code AVP it indicates the success
message. When found in the same message with a Result-Code other than
DIAMETER-SUCCESS it contains the failure message.
The Reply-Message AVP MAY indicate a dialog message to prompt the
user before another AA-Request attempt. When used in an AA-
Challenge-Ind, it MAY indicate a dialog message to prompt the user
for a response.
Multiple Reply-Message's MAY be included and if any are displayed,
they MUST be displayed in the same order as they appear in the
message.
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4.0 Extensible Authentication Protocol Support
The Extensible Authentication Protocol (EAP), described in [25],
provides a standard mechanism for support of additional
authentication methods within PPP. Through the use of EAP, support
for a number of authentication schemes may be added, including smart
and token cards, Kerberos, Public Key, One Time Passwords, and
others.
This section describes the Command-Codes values and AVPs that are
required for an EAP payload to be encapsulated within the DIAMETER
protocol. Since authentication occurs between the PPP client and its
home DIAMETER server, end-to-end authentication is achieved, reducing
the possibility for fraudulent authentication, such as replay and
man-in-the-middle attacks. End-to-end authentication also provides
for mutual (bi-directional) authentication, which is not possible
with PAP and CHAP in a roaming environment.
The DIAMETER/EAP extension allows a home DIAMETER server to initiate
an unsolicited authentication request to the user. This allows the
home server to periodically ensure that the user is still active,
which is useful when a server requires re-authentication to extend
the "life" of a session [26]. Server-initiated authentication can
reduce the number of protocol exchanges over the Internet.
The EAP conversation between the authenticating peer and the NAS
begins with the negotiation of EAP within LCP. Once EAP has been
negotiated, the NAS will typically send to the DIAMETER server a
DIAMETER-EAP-Request message with a NULL EAP-Payload AVP, signifying
an EAP-Start. The Port number and NAS Identifier MUST be included in
the AVPs issued by the NAS in the DIAMETER-EAP-Request packet.
If the DIAMETER home server supports EAP, it MUST respond with a
DIAMETER-EAP-Ind message containing an EAP-Payload AVP that includes
an encapsulated EAP payload [25]. The EAP payload is forwarded by the
NAS to the PPP client. The initial DIAMETER-EAP-Ind normally includes
an EAP-Request/Identity, requesting the PPP client to identify
itself. Upon receipt of the PPP client's EAP-Response [25], the NAS
will then issue a second DIAMETER-EAP-Request message, with the
client's EAP payload encapsulated within the EAP-Payload AVP. The
conversation continues until the DIAMETER server sends a DIAMETER-
EAP-Answer with a Result-Code AVP indicating success or failure. A
Result-Code AVP containing a failure indication SHOULD also include
an EAP-Payload AVP containing an EAP-Failure [25] payload, and the
NAS SHOULD disconnect the PPP client by issuing a LCP terminate. If
the Result-Code AVP indicates success, the EAP-Payload AVP MUST
encapsulate an EAP-Success [25] payload, and the NAS SHOULD
successfully terminate the PPP authentication phase. If authorization
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was requested, a successful DIAMETER-EAP-Answer MUST also include the
appropriate authorization AVPs required for the service requested
(see sections 2.0 and 6.0).
The above scenario creates a situation in which the NAS never needs
to manipulate an EAP packet. An alternative may be used in situations
where an EAP-Request/Identity message will always be sent by the NAS
to the authenticating peer. This involves having the NAS send an
EAP-Request/Identity message to the PPP client, and forwarding the
EAP-Response/Identity packet to the DIAMETER server in the EAP-
Payload AVP of a DIAMETER-EAP-Request packet. While this approach
will save a round-trip, it cannot be universally employed. There are
circumstances in which the user's identity may not be needed (such as
when authentication and accounting is handled based on the calling or
called phone number), and therefore an EAP-Request/Identity packet
may not necessarily be issued by the NAS to the authenticating peer.
Unless the NAS interprets the EAP-Response/Identity packet returned
by the authenticating peer, it will not have access to the user's
identity. Therefore, the DIAMETER Server SHOULD return the user's
identity by inserting it in the User-Name attribute of subsequent
DIAMETER-EAP-Answer packets. Without the user's identity, the
Session-Id AVP MAY be used for accounting and billing, however
operationally this MAY be very difficult to manage.
The DIAMETER-EAP-Ind message MAY be sent by a DIAMETER server in
order to initiate an unsolicited authentication of the PPP user, as
described in [26]. This functionality allows a home DIAMETER server
to easily extend the "life" of a session for a particular service,
while reducing the total number of authentication round-trips, should
the NAS initiate the periodic authentication.
Should an EAP authentication session be interrupted due to a home
server failure, the session MAY be directed to an alternate server,
but the authentication session will have to be restarted from the
beginning.
When DIAMETER is used in a roaming environment, the NAS SHOULD issue
the EAP-Request/Identity request to the PPP client, and forward the
EAP-Response in the initial DIAMETER-EAP-Request message. This allows
any DIAMETER proxies or brokers to identify the user, and forward the
message to the appropriate home server. If a response is received
with the Result-Code set to DIAMETER_COMMAND_UNSUPPORTED [2], it is
an indication that a DIAMETER server in the proxy chain does not
support EAP. The NAS MAY re-open LCP and attempt to negotiate another
PPP authentication protocol, such as PAP or CHAP. A NAS SHOULD be
cautious when determining whether a less secure authentication
protocol will be used, since this could be a result of a bidding down
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attack. See [28] for additional information.
4.1 Alternative uses
Currently the conversation between the backend authentication server
and the DIAMETER server is proprietary because of lack of
standardization. In order to increase standardization and provide
interoperability between DIAMETER vendors and backend security
vendors, it is recommended that DIAMETER-encapsulated EAP be used for
this conversation.
This has the advantage of allowing the DIAMETER server to support EAP
without the need for authentication-specific code within the DIAMETER
server. Authentication-specific code can then reside on a backend
authentication server instead.
In the case where DIAMETER-encapsulated EAP is used in a conversation
between a DIAMETER server and a backend authentication server, the
latter will typically return an DIAMETER-EAP-Answer/EAP-Payload/EAP-
Success message without inclusion of the expected authorization AVPs
required in a successful response. This means that the DIAMETER
server MUST add these attributes prior to sending an DIAMETER-EAP-
Answer/EAP-Payload/EAP-Success message to the NAS.
4.2 Command-Codes Values
This section defines new Command-Code [2] values that MUST be
supported by all DIAMETER implementations conforming to this
specification. The following Command Codes are defined in this
section:
Command-Name Abbrev. Code Reference
--------------------------------------------------------
DIAMETER-EAP-Request DER 268 4.2.1
DIAMETER-EAP-Answer DEA 269 4.2.2
DIAMETER-EAP-Ind DEI 270 4.2.3
DIAMETER-EAP-Terminate DET 275 4.2.4
4.2.1 DIAMETER-EAP-Request (DER) Command
The DIAMETER-EAP-Request (DER) command, indicated by the Command-Code
field set to 268, is sent by a DIAMETER client to a DIAMETER server
and conveys an EAP-Response [25] from the dial-up PPP client. The
DIAMETER-EAP-Request MUST contain one EAP-Payload AVP, which contains
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the actual EAP payload. An EAP-Payload AVP with no data MAY be sent
to the DIAMETER server to initiate an EAP authentication session.
Upon receipt of a DIAMETER-EAP-Request, a DIAMETER server MUST issue
a reply. The reply may be either:
1) a DIAMETER-EAP-Ind containing an EAP-Request encapsulated
within an EAP-Payload attribute
2) a DIAMETER-EAP-Answer containing an EAP-Success encapsulated
within an EAP-Payload and a Result-Code indicating success.
3) a DIAMETER-EAP-Answer containing an EAP-Failure encapsulated
within an EAP-Payload and a Result-Code indicating failure.
4) A Message-Reject-Ind packet with a Result-Code set to
DIAMETER_COMMAND_UNSUPPORTED if a DIAMETER server does not
support the EAP extension.
Message Format
<DIAMETER-EAP-Request> ::= <DIAMETER Header, Command-Code = 268>
<Host-Name AVP>
[<Destination-NAI>]
[<NAS-IP-Address>]
[<NAS-Identifier>]
<EAP-Payload AVP>
<User-Name AVP>
[<Timestamp AVP>
<Initialization-Vector AVP>
<Integrity-Check-Vector AVP>]
4.2.2 DIAMETER-EAP-Answer (DEA) Command
The DIAMETER-EAP-Answer (DEA) message, indicated by the Command-Code
field set to 269, is sent by the DIAMETER server to the client to
indicate either a successful or failed authentication. The DIAMETER-
EAP-Answer message SHOULD include an EAP payload of type EAP-Success
or EAP-Failure encapsulated within an EAP-Payload AVP. The Result-
Code AVP MUST indicate a failure if the EAP-Failure payload is
present, while the AVP MUST indicate success if the EAP-Success
payload is present.
If the message from the DIAMETER client included a request for
authorization, a successful response MUST include the authorization
AVPs that are relevant to the service being provided.
Message Format
<DIAMETER-EAP-Answer> ::= <DIAMETER Header, Command-Code = 269>
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<Result-Code AVP>
<Host-Name AVP>
<Destination-NAI>
[<User-Name AVP>]
[<EAP-Payload AVP>]
[<Authorization AVPs>]
[<Timestamp AVP>
<Initialization-Vector AVP>
<Integrity-Check-Vector AVP>]
4.2.3 DIAMETER-EAP-Ind (DEI) Command
The DIAMETER-EAP-Ind (DEI) command, indicated by the Command-Code set
to 270, has two uses. This message MAY be sent in response to a
DIAMETER-EAP-Request message, and MUST contain an EAP-Response
payload [25] encapsulated within an EAP-Payload AVP.
Alternatively, this message MAY also be sent unsolicited from a
DIAMETER server to a client to request re-authentication of a PPP
client. For re-authentication, it is recommended that the Identity
request be skipped in order to reduce the number of authentication
round trips. This is only possible when the user's identity is
already known by the home DIAMETER server.
Upon receipt of the message, the NAS MUST issue the EAP payload to
the PPP Client, and SHOULD respond with a DIAMETER-EAP-Request
containing the EAP-Response [25] packet.
Message Format
<DIAMETER-EAP-Ind> ::= <DIAMETER Header, Command-Code = 270>
<Host-Name AVP>
<Destination-NAI>
<EAP-Payload AVP>
<User-Name AVP>
[<Timestamp AVP>
<Initialization-Vector AVP>
<Integrity-Check-Vector AVP>]
4.3 EAP-Payload AVP
The EAP-Payload AVP (AVP Code 402) is of type Data and is used to
encapsulate the actual EAP payload [25] that is being exchanged
between the dial-up PPP client and the home DIAMETER server.
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5.0 DIAMETER Session Termination
When a Network Access Server (NAS) receives an indication that a
user's session is being disconnected (e.g. LCP Terminate is
received), the NAS MUST issue a Session-Termination-Request (STR) [2]
to its DIAMETER Server. This will ensure that any resources
maintained on the servers is freed appropriately.
Further, a NAS that receives a Session-Termination-Ind (STI) [2] MUST
disconnect the PPP (or tunneling) session and respond with an STR
message.
6.0 Legacy Authorization AVPs
This section contains the various authorization AVPs that are also
supported by the RADIUS protocol [1]. Use of these AVPs guarantees
interoperability with a RADIUS infrastructure.
6.1 Service Identification AVPs
This section contains the authorization AVPs that are needed to
identify a service, and to allow the server to set constraints on a
session.
6.1.1 NAS-Port AVP
The NAS-Port AVP (AVP Code 5) is of type Integer32 and contains the
physical port number of the NAS which is authenticating the user, and
is normally only present in an authentication and/or authorization
request. Note that this is using "port" in its sense of a physical
connection on the NAS, not in the sense of a TCP or UDP port number.
Either NAS-Port or NAS-Port-Type (AVP Code 61) or both SHOULD be
present in the request, if the NAS differentiates among its ports.
6.1.2 Service-Type AVP
The Service-Type AVP (AVP Code 6) is of type Integer32 and contains
the type of service the user has requested, or the type of service to
be provided. One such AVP MAY be present in an authentication and/or
authorization request or response. A NAS is not required to implement
all of these service types, and MUST treat unknown or unsupported
Service-Types as though a response with a Result-Code other than
DIAMETER-SUCCESS had been received instead.
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When used in a request, the Service-Type AVP SHOULD be considered to
be a hint to the server that the NAS has reason to believe the user
would prefer the kind of service indicated, but the server is not
required to honor the hint. The following values have been defined
for the Service-Type AVP:
Login 1
The user should be connected to a host.
Framed 2
A Framed Protocol should be started for the User, such as PPP or
SLIP.
Callback Login 3
The user should be disconnected and called back, then connected to
a host.
Callback Framed 4
The user should be disconnected and called back, then a Framed
Protocol should be started for the User, such as PPP or SLIP.
Outbound 5
The user should be granted access to outgoing devices.
Administrative 6
The user should be granted access to the administrative interface
to the NAS from which privileged commands can be executed.
NAS Prompt 7
The user should be provided a command prompt on the NAS from which
non-privileged commands can be executed.
Authenticate Only 8
Only Authentication is requested, and no authorization information
needs to be returned in the response.
Callback NAS Prompt 9
The user should be disconnected and called back, then provided a
command prompt on the NAS from which non-privileged commands can
be executed.
6.1.3 Filter-Id AVP
The Filter-Id AVP (AVP Code 11) is of type String and contains the
name of the filter list for this user. Zero or more Filter-Id AVPs
MAY be sent in an authorization response.
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Identifying a filter list by name allows the filter to be used on
different NASes without regard to filter-list implementation details.
However, this AVP is not roaming friendly since filter naming differs
from one service provider to another.
In non-RADIUS environments, it is strongly recommended that the
Filter-Rule AVP be used instead.
6.1.4 Callback-Number AVP
The Callback-Number AVP (AVP Code 19) is of type String and contains
a dialing string to be used for callback. It MAY be used in an
authentication and/or authorization request as a hint to the server
that a Callback service is desired, but the server is not required to
honor the hint in the corresponding response.
The codification of the range of allowed usage of this field is
outside the scope of this specification.
6.1.5 Callback-Id AVP
The Callback-Id AVP (AVP Code 20) is of type String and contains the
name of a place to be called, to be interpreted by the NAS. This AVP
MAY be present in an authentication and/or authorization response.
This AVP is not roaming friendly since it assumes that the Callback-
Id is configured on the NAS. It is therefore preferable to use the
Callback-Number AVP instead.
6.1.6 Idle-Timeout AVP
The Idle-Timeout AVP (AVP Code 28) is of type Integer32 and sets the
maximum number of consecutive seconds of idle connection allowed to
the user before termination of the session or prompt. It MAY be used
in an authentication and/or authorization request (or challenge) as a
hint to the server that an idle timeout is desired, but the server is
not required to honor the hint in the corresponding response.
6.1.7 Called-Station-Id AVP
The Called-Station-Id AVP (AVP Code 30) is of type String and allows
the NAS to send in the request the phone number that the user called,
using Dialed Number Identification (DNIS) or a similar technology.
Note that this may be different from the phone number the call comes
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in on. It SHOULD only be present in authentication and/or
authorization requests.
If the Request-Type AVP is set to authorization-only and the User-
Name AVP is absent, the DIAMETER Server MAY perform authorization
based on this field. This can be used by a NAS to request whether a
call should be answered based on the DNIS.
The codification of the range of allowed usage of this field is
outside the scope of this specification.
6.1.8 Calling-Station-Id AVP
The Calling-Station-Id AVP (AVP Code 31) is of type String and allows
the NAS to send in the request the phone number that the call came
from, using Automatic Number Identification (ANI) or a similar
technology. It SHOULD only be present in authentication and/or
authorization requests.
If the Request-Type AVP is set to authorization-only and the User-
Name AVP is absent, the DIAMETER Server MAY perform authorization
based on this field. This can be used by a NAS to request whether a
call should be answered based on the ANI.
The codification of the range of allowed usage of this field is
outside the scope of this specification.
6.1.9 NAS-Port-Type AVP
The NAS-Port-Type AVP (AVP Code 61) is of type Integer32 and contains
the type of the physical port of the NAS which is authenticating the
user. It can be used instead of or in addition to the NAS-Port (5)
AVP. This AVP SHOULD only be used in authentication and/or
authorization requests. This AVP MAY be combined with the NAS-Port
AVP to assist in differentiating its ports.
The following values are defined:
0 Async
1 Sync
2 ISDN Sync
3 ISDN Async V.120
4 ISDN Async V.110
5 Virtual
6 PIAFS
7 HDLC Clear Channel
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8 X.25
9 X.75
10 G.3 Fax
11 SDSL - Symmetric DSL
12 ADSL-CAP - Asymmetric DSL, Carrierless Amplitude Phase Modulation
13 ADSL-DMT - Asymmetric DSL, Discrete Multi-Tone
14 IDSL - ISDN Digital Subscriber Line
15 Ethernet
16 xDSL
17 Cable
18 Wireless - Other
19 Wireless - IEEE 802.11
"Virtual" refers to a connection to the NAS via some transport
protocol, instead of through a physical port. For example, if a user
telnetted into a NAS to authenticate himself as an Outbound-User, the
request might include NAS-Port-Type = Virtual as a hint to the
DIAMETER server that the user was not on a physical port.
6.1.10 Port-Limit AVP
The Port-Limit AVP (AVP Code 62) is of type Integer32 and sets the
maximum number of ports to be provided to the user by the NAS. It
MAY be used in an authentication and/or authorization request as a
hint to the server that multilink PPP [9] service is desired, but the
server is not required to honor the hint in the corresponding
response.
6.2 Framed Access Authorization AVPs
This section contains the authorization AVPs that are necessary to
support framed access, such as PPP, SLIP, etc.
6.2.1 Framed-Protocol AVP
The Framed-Protocol AVP (AVP Code 7) is of type Integer32 and
contains the framing to be used for framed access. This AVP MAY be
present in both requests and responses. The following values are
currently supported:
1 PPP
2 SLIP
3 AppleTalk Remote Access Protocol (ARAP)
4 Gandalf proprietary SingleLink/MultiLink protocol
5 Xylogics proprietary IPX/SLIP
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6 X.75 Synchronous
6.2.2 Framed-IP-Address AVP
The Framed-IP-Address AVP (AVP Code 8) is of type Address and
contains the address to be configured for the user. It MAY be used in
an authorization request as a hint to the server that a specific
address is desired, but the server is not required to honor the hint
in the corresponding response.
Two addresses have special significance; 0xFFFFFFFF and 0xFFFFFFFE.
The value 0xFFFFFFFF indicates that the NAS should allow the user to
select an address (e.g. Negotiated). The value 0xFFFFFFFE indicates
that the NAS should select an address for the user (e.g. Assigned
from a pool of addresses kept by the NAS).
6.2.3 Framed-IP-Netmask AVP
The Framed-IP-Netmask AVP (AVP Code 9) is of type Address and
contains the IP netmask to be configured for the user when the user
is a router to a network. It MAY be used in an authorization request
as a hint to the server that a specific netmask is desired, but the
server is not required to honor the hint in the corresponding
response. This AVP MUST be present in a response if the request
included this AVP with a value of 0xFFFFFFFF.
6.2.4 Framed-Routing AVP
The Framed-Routing AVP (AVP Code 10) is of type Integer32 and
contains the routing method for the user, when the user is a router
to a network. This AVP SHOULD only be present in authorization
responses. The following values are defined for this AVP:
0 None
1 Send routing packets
2 Listen for routing packets
3 Send and Listen
6.2.5 Framed-MTU AVP
The Framed-MTU AVP (AVP Code 12) is of type Integer32 and contains
the Maximum Transmission Unit to be configured for the user, when it
is not negotiated by some other means (such as PPP). This AVP SHOULD
only be present in authorization responses. The MTU value MUST be
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between the range of 64 and 65535.
6.2.6 Framed-Compression AVP
The Framed-Compression AVP (AVP Code 13) is of type Integer32 and
contains the compression protocol to be used for the link. It MAY be
used in an authorization request as a hint to the server that a
specific compression type is desired, but the server is not required
to honor the hint in the corresponding response.
More than one compression protocol AVP MAY be sent. It is the
responsibility of the NAS to apply the proper compression protocol to
appropriate link traffic.
The following values are defined:
0 None
1 VJ TCP/IP header compression [7]
2 IPX header compression
3 Stac-LZS compression
6.2.7 Framed-IP-Route AVP
The Framed-IP-Route AVP (AVP Code 22) is of type String and contains
the routing information to be configured for the user on the NAS.
Zero or more such AVPs MAY be present in an authorization response.
The string MUST contain a destination prefix in dotted quad form
optionally followed by a slash and a decimal length specifier stating
how many high order bits of the prefix should be used. That is
followed by a space, a gateway address in dotted quad form, a space,
and one or more metrics separated by spaces. For example,
"192.168.1.0/24 192.168.1.1 1".
The length specifier may be omitted in which case it should default
to 8 bits for class A prefixes, 16 bits for class B prefixes, and 24
bits for class C prefixes. For example, "192.168.1.0 192.168.1.1 1".
Whenever the gateway address is specified as "0.0.0.0" the IP address
of the user SHOULD be used as the gateway address.
6.2.8 Framed-IPX-Network AVP
The Framed-IPX-Network AVP (AVP Code 23) is of type String and
contains the IPX Network number to be configured for the user. It MAY
be used in an authorization request as a hint to the server that a
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specific address is desired, but the server is not required to honor
the hint in the corresponding response.
Two addresses have special significance; 0xFFFFFFFF and 0xFFFFFFFE.
The value 0xFFFFFFFF indicates that the NAS should allow the user to
select an address (e.g. Negotiated). The value 0xFFFFFFFE indicates
that the NAS should select an address for the user (e.g. assigned
from a pool of one or more IPX networks kept by the NAS).
6.2.9 Framed-AppleTalk-Link AVP
The Framed-AppleTalk-Link AVP (AVP Code 37) is of type Integer32 and
contains the AppleTalk network number which should be used for the
serial link to the user, which is another AppleTalk router. This AVP
MUST only be present in an authorization response and is never used
when the user is not another router.
Despite the size of the field, values range from zero to 65535. The
special value of zero indicates that this is an unnumbered serial
link. A value of one to 65535 means that the serial line between the
NAS and the user should be assigned that value as an AppleTalk
network number.
6.2.10 Framed-AppleTalk-Network AVP
The Framed-AppleTalk-Network AVP (AVP Code 38) is of type Integer32
and contains the AppleTalk Network number which the NAS should probe
to allocate an AppleTalk node for the user. This AVP MUST only be
present in an authorization response and is never used when the user
is not another router. Multiple instances of this AVP indicate that
the NAS may probe using any of the network numbers specified.
Despite the size of the field, values range from zero to 65535. The
special value zero indicates that the NAS should assign a network for
the user, using its default cable range. A value between one and
65535 (inclusive) indicates the AppleTalk Network the NAS should
probe to find an address for the user.
6.2.11 Framed-AppleTalk-Zone AVP
The Framed-AppleTalk-Zone AVP (AVP Code 39) is of type Data and
contains the AppleTalk Default Zone to be used for this user. This
AVP MUST only be present in an authorization response. Multiple
instances of this AVP in the same message are not allowed.
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The codification of the range of allowed usage of this field is
outside the scope of this specification.
6.3 Non-Framed Access Authorization AVPs
This section contains the authorization AVPs that are needed to
support terminal server functionality.
6.3.1 Login-IP-Host AVP
The Login-IP-Host AVP (AVP Code 14) is of type Address and contains
the system with which to connect the user, when the Login-Service AVP
is included. It MAY be used in an authorization request as a hint to
the server that a specific host is desired, but the server is not
required to honor the hint in the corresponding response.
Two addresses have special significance; 0xFFFFFFFF and 0xFFFFFFFE.
The value 0xFFFFFFFF indicates that the NAS SHOULD allow the user to
select an address. The value zero indicates that the NAS SHOULD
select a host to connect the user to.
6.3.2 Login-Service AVP
The Login-Service AVP (AVP Code 15) is of type Integer32 and contains
the service which should be used to connect the user to the login
host. This AVP SHOULD only be present in authorization responses.
The following values are defined:
0 Telnet
1 Rlogin
2 TCP Clear
3 PortMaster (proprietary)
4 LAT
5 X25-PAD
6 X25-T3POS
8 TCP Clear Quiet (supresses any NAS-generated connect string)
6.3.3 Login-TCP-Port AVP
The Login-TCP-Port AVP (AVP Code 16) is of type Integer32 and
contains the TCP port with which the user is to be connected, when
the Login-Service AVP is also present. This AVP SHOULD only be
present in authorization responses. The value MUST NOT be greater
than 65535.
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6.3.4 Login-LAT-Service AVP
The Login-LAT-Service AVP (AVP Code 34) is of type String and
contains the system with which the user is to be connected by LAT. It
MAY be used in an authorization request as a hint to the server that
a specific service is desired, but the server is not required to
honor the hint in the corresponding response. This AVP MUST only be
present in the response if the Login-Service AVP states that LAT is
desired.
Administrators use the service attribute when dealing with clustered
systems, such as a VAX or Alpha cluster. In such an environment
several different time sharing hosts share the same resources (disks,
printers, etc.), and administrators often configure each to offer
access (service) to each of the shared resources. In this case, each
host in the cluster advertises its services through LAT broadcasts.
Sophisticated users often know which service providers (machines) are
faster and tend to use a node name when initiating a LAT connection.
Alternately, some administrators want particular users to use certain
machines as a primitive form of load balancing (although LAT knows
how to do load balancing itself).
The String field contains the identity of the LAT service to use.
The LAT Architecture allows this string to contain $ (dollar), -
(hyphen), . (period), _ (underscore), numerics, upper and lower case
alphabetics, and the ISO Latin-1 character set extension [8]. All LAT
string comparisons are case insensitive.
6.3.5 Login-LAT-Node AVP
The Login-LAT-Node AVP (AVP Code 35) is of type String and contains
the Node with which the user is to be automatically connected by LAT.
It MAY be used in an authorization request as a hint to the server
that a specific LAT node is desired, but the server is not required
to honor the hint in the corresponding response. This AVP MUST only
be present in a response if the Service-Type AVP is set to LAT.
The String field contains the identity of the LAT service to use.
The LAT Architecture allows this string to contain $ (dollar), -
(hyphen), . (period), _ (underscore), numerics, upper and lower case
alphabetics, and the ISO Latin-1 character set extension [8]. All LAT
string comparisons are case insensitive.
6.3.6 Login-LAT-Group AVP
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The Login-LAT-Group AVP (AVP Code 36) is of type Data and contains a
string identifying the LAT group codes which this user is authorized
to use. It MAY be used in an authorization request as a hint to the
server that a specific group is desired, but the server is not
required to honor the hint in the corresponding response. This AVP
MUST only be present in a response if the Service-Type AVP is set to
LAT.
LAT supports 256 different group codes, which LAT uses as a form of
access rights. LAT encodes the group codes as a 256 bit bitmap.
Administrators can assign one or more of the group code bits at the
LAT service provider; it will only accept LAT connections that have
these group codes set in the bit map. The administrators assign a
bitmap of authorized group codes to each user; LAT gets these from
the operating system, and uses these in its requests to the service
providers.
The codification of the range of allowed usage of this field is
outside the scope of this specification.
6.3.7 Login-LAT-Port AVP
The Login-LAT-Port AVP (AVP Code 63) is of type String and contains
the Port with which the user is to be connected by LAT. It MAY be
used in an authorization request as a hint to the server that a
specific port is desired, but the server is not required to honor the
hint in the corresponding response. This AVP MUST only be present in
a response if the Service-Type AVP is set to LAT.
The String field contains the identity of the LAT service to use.
The LAT Architecture allows this string to contain $ (dollar), -
(hyphen), . (period), _ (underscore), numerics, upper and lower case
alphabetics, and the ISO Latin-1 character set extension [8]. All LAT
string comparisons are case insensitive.
6.4 Tunneling AVPs
This section contains the authorization AVPs that are needed for a
NAS to support tunneling users.
6.4.1 Tunnel-Type AVP
The Tunnel-Type AVP (AVP Code 64) is of type Integer32 and contains
the tunneling protocol(s) to be used (in the case of a tunnel
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initiator) or the the tunneling protocol in use (in the case of a
tunnel terminator). It MAY be used in an authorization request as a
hint to the server that a specific tunnel type is desired, but the
server is not required to honor the hint in the corresponding
response.
The Tunnel-Type SHOULD also be present in the corresponding ADIF
Record within the Accounting-Request.
A tunnel initiator is not required to implement any of these tunnel
types; if a tunnel initiator receives a response that contains only
unknown or unsupported Tunnel-Types, the tunnel initiator MUST behave
as though a response was received with the Result-Code indicating a
failure.
The following values have been defined:
1 Point-to-Point Tunneling Protocol (PPTP) [14]
2 Layer Two Forwarding (L2F) [15]
3 Layer Two Tunneling Protocol (L2TP) [16]
4 Ascend Tunnel Management Protocol (ATMP) [17]
5 Virtual Tunneling Protocol (VTP)
6 IP Authentication Header in the Tunnel-mode (AH) [18]
7 IP-in-IP Encapsulation (IP-IP) [19]
8 Minimal IP-in-IP Encapsulation (MIN-IP-IP) [20]
9 IP Encapsulating Security Payload in the Tunnel-mode (ESP) [21]
10 Generic Route Encapsulation (GRE) [22]
11 Bay Dial Virtual Services (DVS)
12 IP-in-IP Tunneling [23]
6.4.2 Tunnel-Medium-Type AVP
The Tunnel-Medium-Type AVP (AVP Code 65) is of type Integer32 and
contains the transport medium to use when creating a tunnel for those
protocols (such as L2TP) that can operate over multiple transports.
It MAY be used in an authorization request as a hint to the server
that a specific medium is desired, but the server is not required to
honor the hint in the corresponding response.
The Value field is three octets and contains one of the values listed
under "Address Family Numbers" in [10]. The value of most importance
is (1) for IPv4 and (2) for IPv6.
6.4.3 Tunnel-Client-Endpoint AVP
The Tunnel-Client-Endpoint AVP (AVP Code 66) is of type String and
contains the address of the initiator end of the tunnel. It MAY be
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used in an authorization request as a hint to the server that a
specific endpoint is desired, but the server is not required to honor
the hint in the corresponding response.
This AVP SHOULD be included in the ADIF Record of the corresponding
Accounting-Request messages, in which case it indicates the address
from which the tunnel was initiated. This AVP, along with the
Tunnel-Server-Endpoint and Session-Id AVP [2], MAY be used to provide
a globally unique means to identify a tunnel for accounting and
auditing purposes.
If Tunnel-Medium-Type is IPv4 (1), then this string is either the
fully qualified domain name (FQDN) of the tunnel client machine, or
it is a "dotted-decimal" IP address. Conformant implementations MUST
support the dotted-decimal format and SHOULD support the FQDN format
for IP addresses.
If Tunnel-Medium-Type is IPv6 (2), then this string is either the
FQDN of the tunnel client machine, or it is a text representation of
the address in either the preferred or alternate form [5].
Conformant implementations MUST support the preferred form and SHOULD
support both the alternate text form and the FQDN format for IPv6
addresses.
If Tunnel-Medium-Type is neither IPv4 nor IPv6, this string is a tag
referring to configuration data local to the DIAMETER client that
describes the interface and medium-specific address to use.
6.4.4 Tunnel-Server-Endpoint AVP
The Tunnel-Server-Endpoint AVP (AVP Code 67) is of String and
contains the address of the server end of the tunnel. It MAY be used
in an authorization request as a hint to the server that a specific
endpoint is desired, but the server is not required to honor the hint
in the corresponding response.
This AVP SHOULD be included in the ADIF Record of the corresponding
Accounting-Request messages, in which case it indicates the address
from which the tunnel was initiated. This AVP, along with the
Tunnel-Client-Endpoint and Session-Id AVP [2], MAY be used to provide
a globally unique means to identify a tunnel for accounting and
auditing purposes.
If Tunnel-Medium-Type is IPv4 (1), then this string is either the
fully qualified domain name (FQDN) of the tunnel client machine, or
it is a "dotted-decimal" IP address. Conformant implementations MUST
support the dotted-decimal format and SHOULD support the FQDN format
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for IP addresses.
If Tunnel-Medium-Type is IPv6 (2), then this string is either the
FQDN of the tunnel client machine, or it is a text representation of
the address in either the preferred or alternate form [5].
Conformant implementations MUST support the preferred form and SHOULD
support both the alternate text form and the FQDN format for IPv6
addresses.
If Tunnel-Medium-Type is not IPv4 or IPv6, this string is a tag
referring to configuration data local to the DIAMETER client that
describes the interface and medium-specific address to use.
6.4.5 Tunnel-Password AVP
The Tunnel-Password AVP (AVP Code 69) is of type Data and may contain
a password to be used to authenticate to a remote server. This AVP
MUST only be present in authorization responses in an encrypted form,
using one of the methods described in [2] and [13].
6.4.6 Tunnel-Private-Group-ID AVP
The Tunnel-Private-Group-ID AVP (AVP Code 81) is of type String and
contains the group ID for a particular tunneled session. The Tunnel-
Private-Group-ID AVP MAY be included in an authorization request if
the tunnel initiator can pre-determine the group resulting from a
particular connection and SHOULD be included in the authorization
response if this tunnel session is to be treated as belonging to a
particular private group. Private groups may be used to associate a
tunneled session with a particular group of users. For example, it
MAY be used to facilitate routing of unregistered IP addresses
through a particular interface. This value SHOULD be included the
corresponding ADIF-Record in the Accounting-Request which pertain to
a tunneled session.
6.4.7 Tunnel-Assignment-ID AVP
The Tunnel-Assignment-ID AVP (AVP Code 82) is of type String and is
used to indicate to the tunnel initiator the particular tunnel to
which a session is to be assigned. Some tunneling protocols, such as
PPTP and L2TP, allow for sessions between the same two tunnel
endpoints to be multiplexed over the same tunnel and also for a given
session to utilize its own dedicated tunnel. This attribute provides
a mechanism for DIAMETER to be used to inform the tunnel initiator
(e.g. PAC, LAC) whether to assign the session to a multiplexed
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tunnel or to a separate tunnel. Furthermore, it allows for sessions
sharing multiplexed tunnels to be assigned to different multiplexed
tunnels.
A particular tunneling implementation may assign differing
characteristics to particular tunnels. For example, different
tunnels may be assigned different QOS parameters. Such tunnels may
be used to carry either individual or multiple sessions. The
Tunnel-Assignment-ID attribute thus allows the DIAMETER server to
indicate that a particular session is to be assigned to a tunnel that
provides an appropriate level of service. It is expected that any
QOS-related DIAMETER tunneling attributes defined in the future that
accompany this attribute will be associated by the tunnel initiator
with the ID given by this attribute. In the meantime, any semantic
given to a particular ID string is a matter left to local
configuration in the tunnel initiator.
The Tunnel-Assignment-ID AVP is of significance only to DIAMETER and
the tunnel initiator. The ID it specifies is intended to be of only
local use to DIAMETER and the tunnel initiator. The ID assigned by
the tunnel initiator is not conveyed to the tunnel peer.
This attribute MAY be included in authorization responses. The tunnel
initiator receiving this attribute MAY choose to ignore it and assign
the session to an arbitrary multiplexed or non-multiplexed tunnel
between the desired endpoints. This attribute SHOULD also be
included in the corresponding ADIF-Record in the Accounting-Request
messages which pertain to a tunneled session.
If a tunnel initiator supports the Tunnel-Assignment-ID AVP, then it
should assign a session to a tunnel in the following manner:
- If this AVP is present and a tunnel exists between the specified
endpoints with the specified ID, then the session should be
assigned to that tunnel.
- If this AVP is present and no tunnel exists between the
specified endpoints with the specified ID, then a new tunnel
should be established for the session and the specified ID
should be associated with the new tunnel.
- If this AVP is not present, then the session is assigned to an
unnamed tunnel. If an unnamed tunnel does not yet exist between
the specified endpoints then it is established and used for this
and subsequent sessions established without the Tunnel-
Assignment-ID attribute. A tunnel initiator MUST NOT assign a
session for which a Tunnel-Assignment-ID AVP was not specified
to a named tunnel (i.e. one that was initiated by a session
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specifying this AVP).
Note that the same ID may be used to name different tunnels if such
tunnels are between different endpoints.
6.4.8 Tunnel-Preference AVP
The Tunnel-Preference AVP (AVP Code 83) is of type Integer32 and is
used to identify the relative preference assigned to each tunnel when
more than one set of tunneling AVPs is returned within separete
Grouped-AVP AVPs. It MAY be used in an authorization request as a
hint to the server that a specific preference is desired, but the
server is not required to honor the hint in the corresponding
response.
For example, suppose that AVPs describing two tunnels are returned by
the server, one with a Tunnel-Type of PPTP and the other with a
Tunnel-Type of L2TP. If the tunnel initiator supports only one of
the Tunnel-Types returned, it will initiate a tunnel of that type.
If, however, it supports both tunnel protocols, it SHOULD use the
value of the Tunnel-Preference AVP to decide which tunnel should be
started. The tunnel having the numerically lowest value in the Value
field of this AVP SHOULD be given the highest preference. The values
assigned to two or more instances of the Tunnel-Preference AVP within
a given authorization response MAY be identical. In this case, the
tunnel initiator SHOULD use locally configured metrics to decide
which set of AVPs to use.
6.4.9 Tunnel-Client-Auth-ID AVP
The Tunnel-Client-Auth-ID AVP (AVP Code 90) is of type String and
specifies the name used by the tunnel initiator during the
authentication phase of tunnel establishment. It MAY be used in an
authorization request as a hint to the server that a specific
preference is desired, but the server is not required to honor the
hint in the corresponding response. This AVP MUST be present in the
authorization response if an authentication name other than the
default is desired. This AVP SHOULD be included in the corresponding
ADIF-Record of the Accounting-Request messages which pertain to a
tunneled session.
6.4.10 Tunnel-Server-Auth-ID AVP
The Tunnel-Server-Auth-ID AVP (AVP Code 91) is of type String and
specifies the name used by the tunnel terminator during the
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authentication phase of tunnel establishment. It MAY be used in an
authorization request as a hint to the server that a specific
preference is desired, but the server is not required to honor the
hint in the corresponding response. This AVP MUST be present in the
authorization response if an authentication name other than the
default is desired. This AVP SHOULD be included in the corresponding
ADIF-Record of the Accounting-Request messages which pertain to a
tunneled session.
7.0 Interactions with Resource Management
The Resource Management extension [31] provides the ability for a
DIAMETER node to query a peer for session state information. The
document states that service-specific extensions are responsible for
specifying what AVPs are to be present in the Resource-Token [31]
AVP.
In addition to the AVPs listed in [31], the Resource-Token with the
Extension-Id AVP set to one (1) MUST include the Service-Type AVP. In
the event of a framed (PPP) user, the Framed-IP-Address and Framed-
IPX-Network MUST be present if the corresponding network is being
used. For Login users, the Login-IP-Host AVP and Login-Service AVP
MUST be present. For tunneling users, the Tunnel-Type, Tunnel-
Medium-Type, Tunnel-Client-Endpoint, and the Tunnel-Server-Endpoint
AVPs MUST be present.
8.0 IANA Considerations
The command codes defined in Sections 3.1 and 4.2 are values taken
from the Command-Code [2] address space and extended in [13], [29]
and [30]. IANA should record the values as defined in Sections 2.1
and 4.2.
The AVPs defined in section 2.1 were alllocated from from the AVP
numbering space defined in [2], and extended in [13], [29] and [30].
IANA should record the values as defined in Sections 2.1.
The DIAMETER base protocol [2] reserves the first 255 AVPs for legacy
RADIUS support [1]. The AVPs defined in section 2.2 are defined in
[1], and no number assignment is necessary.
8.1 Request-Type AVP Values
The Request-Type AVP (section 2.1.1) has a set of values that MUST be
maintained by IANA. Values 1 through 3 are defined in this document.
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The remaining values are available for assignment via Designated
Expert [27].
9.0 Security Considerations
This document does not contain any security protocol, but does
discuss how PPP authentication protocols can be carried within the
DIAMETER protocol. The PPP authentication protocols that are
described are PAP, CHAP and EAP.
The use of PAP SHOULD be discouraged, since it exposes user's
passwords to possibly non-trusted entities. PAP is also frequently
used for use with One-Time Passwords (OTP), which does not expose any
security risks. However, it is highly recommended that OTP be
supported through the EAP protocol.
This document also describes how CHAP can be carried within the
DIAMETER protocol, which is required for backward RADIUS
compatibility. The CHAP protocol, as used in a RADIUS environment,
facilitates authentication replay attacks, and therefore SHOULD NOT
be used when EAP is available.
10.0 References
[1] Rigney, et alia, "RADIUS", RFC-2138, Livingston, April 1997
[2] Calhoun, Rubens, Akhtar, Guttman, "DIAMETER Base Protocol",
draft-calhoun-diameter-17.txt, IETF work in progress, September
2000.
[3] Aboba, Beadles, "The Network Access Identifier." RFC 2486. Janu-
ary 1999.
[4] Aboba, Zorn, "Criteria for Evaluating Roaming Protocols", RFC
2477, January 1999.
[5] Hinden, R., Deering, S., "IP Version 6 Addressing Architecture",
RFC 2373, July 1998
[6] W. Simpson, "PPP Challenge Handshake Authentication Protocol
(CHAP)", RFC 1994, August 1996.
[7] Jacobson, "Compressing TCP/IP headers for low-speed serial
links", RFC 1144, February 1990.
Calhoun et al. expires March 2001 [Page 35]
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[8] ISO 8859. International Standard -- Information Processing --
8-bit Single-Byte Coded Graphic Character Sets -- Part 1: Latin
Alphabet No. 1, ISO 8859-1:1987.
<URL:http://www.iso.ch/cate/d16338.html>
[9] Sklower, Lloyd, McGregor, Carr, "The PPP Multilink Protocol
(MP)", RFC 1717, November 1994.
[10] Reynolds, J., Postel, J., "Assigned Numbers", STD 2, RFC 1700,
October 1994
[11] Calhoun, Zorn, Pan, Akhtar, "DIAMETER Framework", draft-
calhoun-diameter-framework-07.txt, IETF work in progress, April
2000.
[12] S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[13] P. Calhoun, W. Bulley, S. Farrell, "DIAMETER Strong Security
Extension", draft-calhoun-diameter-strong-crypto-05.txt, IETF
work in progress, September 2000.
[14] Hamzeh, K., Pall, G., Verthein, W., Taarud, J., Little, W.,
Zorn, G., "Point-to-Point Tunneling Protocol (PPTP)", RFC 2637,
July 1999
[15] Valencia, A., Littlewood, M., Kolar, T., "Cisco Layer Two For-
warding (Protocol) 'L2F'", RFC 2341, May 1998
[16] Townsley, W. M., Valencia, A., Rubens, A., Pall, G. S., Zorn,
G., Palter, B., "Layer Two Tunneling Protocol (L2TP)", RFC 2661,
August 1999
[17] Hamzeh, K., "Ascend Tunnel Management Protocol - ATMP", RFC
2107, February 1997
[18] Kent, S., Atkinson, R., "Security Architecture for the Internet
Protocol", RFC 2401, November 1998
[19] Perkins, C., "IP Encapsulation within IP", RFC 2003, October
1996
[20] Perkins, C., "Minimal Encapsulation within IP", RFC 2004,
October 1996
[21] Atkinson, R., "IP Encapsulating Security Payload (ESP)", RFC
1827, August 1995
Calhoun et al. expires March 2001 [Page 36]
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[22] Hanks, S., Li, T., Farinacci, D., Traina, P., "Generic Routing
Encapsulation (GRE)", RFC 1701, October 1994
[23] Simpson, W., "IP in IP Tunneling", RFC 1853, October 1995
[24] M. Beadles, D. Mitton, "Criteria for Evaluating Network Access
Server Protocols", draft-ietf-nasreq-criteria-05.txt, IETF work
in progress, June 2000.
[25] L. J. Blunk, J. R. Vollbrecht, "PPP Extensible Authentication
Protocol (EAP)." RFC 2284, March 1998.
[26] G. Zorn, P. R. Calhoun, "Limiting Fraud in Roaming", draft-
ietf-roamops-fraud-limit-00.txt, IETF work in progress, May
1999.
[27] Narten, Alvestrand, "Guidelines for Writing an IANA Considera-
tions Section in RFCs", BCP 26, RFC 2434, October 1998
[28] P. Calhoun, A. Rubens, H. Akhtar, E. Guttman, W. Bulley, J.
Haag, "DIAMETER Implementation Guidelines", draft-calhoun-
diameter-impl-guide-03.txt, IETF work in progress, June 2000.
[29] J. Arkko, P. Calhoun, P. Patel, G. Zorn, "DIAMETER Accounting
Extension", draft-calhoun-diameter-accounting-08.txt, IETF work
in progress, September 2000.
[30] P. Calhoun, C. Perkins, "DIAMETER Mobile IP Extensions", draft-
calhoun-diameter-mobileip-11.txt, IETF work in progress, Sep-
tember 2000.
[31] P. Calhoun, N. Greene, "DIAMETER Resource Management", draft-
calhoun-diameter-res-mgmt-05.txt, IETF Work in Progress, Sep-
tember 2000.
11.0 Acknowledgements
The authors would also like to acknowledge the following people for
their contribution in the development of the DIAMETER protocol:
Bernard Aboba, Jari Arkko, William Bulley, Daniel C. Fox, Lol Grant,
Ignacio Goyret, Nancy Greene, Peter Heitman, Paul Krumviede, Fergal
Ladley, Ryan Moats, Victor Muslin, Kenneth Peirce, Sumit Vakil, John
R. Vollbrecht, Jeff Weisberg and Glen Zorn
12.0 Authors' Addresses
Calhoun et al. expires March 2001 [Page 37]
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Questions about this memo can be directed to:
Pat R. Calhoun
Network and Security Research Center, Sun Labs
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, California, 94025
USA
Phone: +1 650-786-7733
Fax: +1 650-786-6445
E-mail: pcalhoun@eng.sun.com
William Bulley
Merit Network, Inc.
Building One, Suite 2000
4251 Plymouth Road
Ann Arbor, Michigan 48105-2785
USA
Phone: +1 734-764-9993
Fax: +1 734-647-3185
E-mail: web@merit.edu
Allan C. Rubens
Tut Systems, Inc.
220 E. Huron, Suite 260
Ann Arbor, MI 48104
USA
Phone: +1 734-995-1697
E-Mail: arubens@tutsys.com
Jeff Haag
Cisco Systems
7025 Kit Creek Road
PO Box 14987
Research Triangle Park, NC 27709
Phone: 1-919-392-2353
E-Mail: haag@cisco.com
13.0 Full Copyright Statement
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Copyright (C) The Internet Society (1999). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing the
copyright notice or references to the Internet Society or other Internet
organizations, except as needed for the purpose of developing
Internet standards in which case the procedures for copyrights defined
in the Internet Standards process must be followed, or as required to
translate it into languages other than English. The limited permissions
granted above are perpetual and will not be revoked by the
Internet Society or its successors or assigns. This document and the
information contained herein is provided on an "AS IS" basis and THE
INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY
THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY
RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
Calhoun et al. expires March 2001 [Page 39]