Internet DRAFT - draft-jiang-softwire-4rd-radius
draft-jiang-softwire-4rd-radius
Network Working Group Sheng Jiang (Editor)
Internet Draft Yu Fu
Intended status: Standards Track Bing Liu
Expires: August 18, 2014 Huawei Technologies Co., Ltd
February 14, 2014
RADIUS Attribute for 4rd
draft-jiang-softwire-4rd-radius-04.txt
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Abstract
IPv4 Residual Deployment via IPv6 (4rd) is a stateless mechanism for
running IPv4 over IPv6-only infrastructure. It provides both IPv4 and
IPv6 connectivity services simultaneously during the IPv4/IPv6 co-
existing period. The Dynamic Host Configuration Protocol for IPv6
(DHCPv6) 4rd options has been defined to configure 4rd Customer Edge
(CE). However, in many networks, the configuration information may be
stored in Authentication Authorization and Accounting (AAA) servers
while user configuration is mainly from Broadband Network Gateway
(BNG) through DHCPv6 protocol. This document defines a Remote
Authentication Dial In User Service (RADIUS) attribute that carries
4rd configuration information from AAA server to BNG. The 4rd RADIUS
attribute are designed following the simplify principle. It provides
just enough information to form the correspondent DHCPv6 4rd option.
Table of Contents
1. Introduction ................................................. 3
2. Terminology .................................................. 3
3. 4rd Configuration process with RADIUS ........................ 3
4. Attributes ................................................... 6
4.1. 4rd-Configuration Attribute ............................. 6
4.2. 4rd Non-mapping-rule Parameter option ................... 7
4.3. 4rd Rule Options ........................................ 7
4.4. 4rd Rule Sub Options .................................... 8
4.4.1. Rule-IPv6-Prefix Sub Option ........................ 8
4.4.2. Rule-IPv6-Suffix Sub Option ........................ 9
4.4.3. Rule-IPv4-Prefix Sub Option ....................... 10
4.4.4. Misc Sub Option ................................... 11
4.5. Table of attributes .................................... 11
5. Diameter Considerations ..................................... 12
6. Security Considerations ..................................... 12
7. IANA Considerations ......................................... 12
8. Acknowledgments ............................................. 13
9. References .................................................. 13
9.1. Normative References ................................... 13
9.2. Informative References ................................. 13
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1. Introduction
Recently providers start to deploy IPv6 and consider how to transit
to IPv6. IPv4 Residual Deployment via IPv6 (4rd)
[I-D.ietf-softwire-4rd] is a stateless mechanism for running IPv4
over IPv6-only infrastructure. It provides both IPv4 and IPv6
connectivity services simultaneously during the IPv4/IPv6 co-existing
period. 4rd has adopted Dynamic Host Configuration Protocol for IPv6
(DHCPv6) [RFC3315] as auto-configuring protocol. The 4rd Customer
Edge (CE) uses the DHCPv6 extension options
[I-D.ietf-softwire-4rd] to discover 4rd Border Relay and to configure
relevant 4rd rules.
In many networks, user configuration information may be managed by
AAA (Authentication, Authorization, and Accounting) servers. Current
AAA servers communicate using the Remote Authentication Dial In User
Service (RADIUS) [RFC2865] protocol. In a fixed line broadband
network, the Broadband Network Gateways (BNGs) act as the access
gateway of users. The BNGs are assumed to embed a DHCPv6 server
function that allows them to locally handle any DHCPv6 requests
issued by hosts.
Since the 4rd configuration information is stored in AAA servers and
user configuration is mainly through DHCPv6 protocol between BNGs and
hosts/CEs, new RADIUS attributes are needed to propagate the
information from AAA servers to BNGs. The 4rd RADIUS attribute are
designed following the simplify principle, while providing enough
information to form the correspondent DHCPv6 4rd option.
[I-D.ietf-softwire-4rd].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
The terms 4rd CE and 4rd Border Relay are defined in
[I-D.ietf-softwire-4rd].
3. 4rd Configuration process with RADIUS
The below Figure 1 illustrates how the RADIUS protocol and DHCPv6
cooperate to provide 4rd CE with 4rd configuration information.
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4rd CE BNG AAA Server
| | |
|------DHCPv6 Solicit----->| |
|(Option Request w/ 4rd option) |
| |--Access-Request(4rd Attr)-->|
| | |
| |<--Access-Accept(4rd Attr)---|
|<---DHCPv6 Advertisement--| |
| | |
|------DHCPv6 Request---->| |
| (4rd Option) | |
|<---- -DHCPv6 Reply-------| |
| (4rd option) | |
| | |
DHCPv6 RADIUS
Figure 1: the cooperation between DHCPv6 and RADIUS
combining with RADIUS authentication
BNGs act as a client of RADIUS and as a DHCPv6 server. First, the
4rd CE MAY initiate a DHCPv6 Solicit message that includes an Option
Request option (6) [RFC3315] with the 4rd option
[draft-ietf-softwire-4rd] from the 4rd CE. When BNG receives the
SOLICIT, it SHOULD initiate an RADIUS Access-Request message, in
which the User-Name attribute (1) SHOULD be filled by the 4rd CE MAC
address, to the RADIUS server and the User-password attribute (2)
SHOULD be filled by the shared 4rd password that has been
preconfigured on the DHCPv6 server, requesting authentication as
defined in [RFC2865] with 4rd-Configuration attribute, defined in the
next Section. If the authentication request is approved by the AAA
server, an Access-Accept message MUST contain the 4rd-Configuration
Attribute. After receiving the Access-Accept message with 4rd-
Configuration Attribute, the BNG SHOULD respond to the user with an
Advertisement message. Then the user can request a 4rd Option, the
BNG SHOULD reply the user with a message containing the 4rd option.
The recommended format of the MAC address is as defined in Calling-
Station-Id (Section 3.20 in [RFC3580]) without the SSID (Service Set
Identifier) portion.
Figure 2 describes another scenario, in which the authorization
operation is not coupled with authentication. Authorization relevant
to 4RD is done independently after the authentication process.
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4rd CE BNG AAA Server
| | |
|------DHCPv6 Request---->| |
|(Option Request w/ 4rd option) |
| |--Access-Request(4rd Attr)-->|
| | |
| |<--Access-Accept(4rd Attr)---|
| | |
|<------DHCPv6 Reply-------| |
| (4rd option) | |
| | |
DHCPv6 RADIUS
Figure 2: the cooperation between DHCPv6 and RADIUS
decoupled with RADIUS authentication
In the abovementioned scenario, the Access-Request packet SHOULD
contain a Service-Type attribute (6) with the value Authorize Only
(17); thus, according to [RFC5080], the Access-Request packet MUST
contain a State attribute that obtained from the previous
authentication process.
In both above-mentioned scenarios, Message-authenticator (type 80)
[RFC2869] SHOULD be used to protect both Access-Request and Access-
Accept messages.
After receiving the 4rd-Configuration Attribute in the initial
Access-Accept, the BNG SHOULD store the received 4rd configuration
parameters locally. When the 4rd CE sends a DHCPv6 Request message to
request an extension of the lifetimes for the assigned address, the
BNG does not have to initiate a new Access-Request towards the AAA
server to request the 4rd configuration parameters. The BNG could
retrieves the previously stored 4rd configuration parameters and use
them in its reply.
If the BNG does not receive the 4rd-Configuration Attribute in the
Access-Accept it MAY fallback to a pre-configured default 4rd
configuration, if any. If the BNG does not have any pre-configured
default 4rd configuration or if the BNG receives an Access-Reject,
the tunnel cannot be established.
As specified in [RFC3315], section 18.1.4, "Creation and Transmission
of Rebind Messages ", if the DHCPv6 server to which the DHCPv6 Renew
message was sent at time T1 has not responded by time T2, the 4rd CE
(DHCPv6 client) enters the Rebind state and attempts to contact any
available server. In this situation the secondary BNG receiving the
DHCPv6 message MUST initiate a new Access-Request towards the AAA
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server. The secondary BNG MAY include the 4rd-Configuration Attribute
in its Access-Request.
4. Attributes
This section defines 4rd-Configuration Attribute which is used in the
4rd scenario. The attribute design follows [RFC6158].
The 4rd RADIUS attribute are designed following the simplify
principle. The sub options are organized into two categories: the
necessary and the optional.
4.1. 4rd-Configuration Attribute
The 4rd-Configuration Attribute is structured as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+ 4rd Option(s) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBD
Length
6 + the length of the Rule option(s)
Sub Option
a variable field that may contains a 4rd non-mapping-rule
parameter option andone or more Rule option(s), defined in
Section 4.2 and 4.3.
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4.2. 4rd Non-mapping-rule Parameter option
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code = OPTION_4RD | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|H| 0 |T| traffic-class | domain-pmtu |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
1
Length
4
H bit
Hub&spoke topology (= 1 if Yes)
T bit
Traffic-class flag (= 1 if a Tunnel traffic class is provided)
traffic-class
Tunnel-traffic class
domain-pmtu
Domain PMTU (at least 1280)
4.3. 4rd Rule Options
Depending on deployment scenario, at least one BR Mapping Rule one
and one or more CE Mapping Rules MUST be included in one 4rd-
Configuration Attribute.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+ Sub Options +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
2 BR Mapping Rule
3 CE Mapping Rule
Length
2 + the length of the sub options
Sub Option
a variable field that contains necessary sub options defined in
Section 4.3 and zero or several optional sub options, defined
in Section 4.4.
4.4. 4rd Rule Sub Options
Rule-IPv6-Prefix Sub Option and Rule-IPv4-Prefix Sub Option are
necessary for every 4rd Rule option. They should appear for once and
only once. Different from [I-D.ietf-softwire-4rd], EA-Len, Embedded-
Address (EA) length, is not present at all, because it can be
calculated by the combine of prefix4len, prefix6-len, excluded ports
and off bits.
4.4.1. Rule-IPv6-Prefix Sub Option
The IPv6 Prefix sub option is follow the framed IPv6 prefix designed
in [RFC3162].
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SubType | SubLen | Reserved | prefix6-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| rule-ipv6-prefix |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SubType
0 (SubType number, for the Rule-IPv6-Prefix6 sub option)
SubLen
20 (the length of the Rule-IPv6-Prefix6 sub option)
Reserved
Reserved for future usage. It should be set to all zero.
prefix6-len
length of the IPv6 prefix, specified in the rule-ipv6-prefix
field, expressed in bits
rule-ipv6-prefix
a 128-bits field that specifies an IPv6 prefix that appears in
a 4rd rule
4.4.2. Rule-IPv6-Suffix Sub Option
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SubType | SubLen | suffix6-len | ipv6-suffix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SubType
1 (SubType number, for the Rule-IPv6-Suffix6 sub option)
SubLen
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4 (the length of the Rule-IPv6-Suffix6 sub option)
prefix6-len
length of the IPv6 suffix, specified in the rule-ipv6-suffix
field, expressed in bits. In attendance, the value should be
1~4 only.
rule-ipv6-suffix
a 8-bits field that specifies an IPv6 suffix that appears in
a 4rd rule
4.4.3. Rule-IPv4-Prefix Sub Option
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SubType | SubLen | Reserved | prefix4-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rule-ipv4-prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SubType
2 (SubType number, for the Rule-IPv4-Prefix6 sub option)
SubLen
8 (the length of the Rule-IPv4-Prefix6 sub option)
Reserved
Reserved for future usage. It should be set to all zero.
Prefix4-len
length of the IPv6 prefix, specified in the rule-ipv6-prefix
field, expressed in bits
rule-ipv4-prefix
a 32-bits field that specifies an IPv4 prefix that appears in
a 4rd rule
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4.4.4. Misc Sub Option
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SubType | SubLen | Reserved |W|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SubType
3 (SubType number, for the Rule-IPv4-Prefix6 sub option)
SubLen
1 (the length of the Rule-IPv4-Prefix6 sub option)
Reserved
Reserved for future usage. It should be set to all zero.
W bit
WKP authorized, = 1 if set
4.5. Table of attributes
The following table provides a guide to which attributes may be found
in which kinds of packets, and in what quantity.
Request Accept Reject Challenge Accounting # Attribute
Request
0-1 0-1 0 0 0-1 TBD1 4rd-
Configuration
0-1 0-1 0 0 0-1 1 User-Name
0-1 0 0 0 0-1 2 User-Password
0-1 0-1 0 0 0-1 6 Service-Type
0-1 0-1 0-1 0-1 0-1 80 Message-Authenticator
The following table defines the meaning of the above table entries.
0 This attribute MUST NOT be present in packet.
0+ Zero or more instances of this attribute MAY be present in
packet.
0-1 Zero or one instance of this attribute MAY be present in
packet.
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1 Exactly one instance of this attribute MUST be present in
packet.
5. Diameter Considerations
This attribute is usable within either RADIUS or Diameter [RFC6733].
Since the Attributes defined in this document will be allocated from
the standard RADIUS type space, no special handling is required by
Diameter entities.
6. Security Considerations
In 6rd scenarios, both CE and BNG are within a provider network,
which can be considered as a closed network and a lower security
threat environment. A similar consideration can be applied to the
RADIUS message exchange between BNG and the AAA server.
Known security vulnerabilities of the RADIUS protocol are discussed
in RFC 2607 [RFC2607], RFC 2865 [RFC2865], and RFC 2869 [RFC2869].
Use of IPsec [RFC4301] for providing security when RADIUS is carried
in IPv6 is discussed in RFC 3162 [RFC3162].
A malicious user may use MAC address spoofing and/or dictionary
attack on the shared 4rd password that has been preconfigured on the
DHCPv6 server to get unauthorized 4rd configuration information.
Security considerations for 4RD specific between 4RD CE and BNG are
discussed in [I-D.ietf-softwire-4rd]. Furthermore, generic DHCPv6
security mechanisms can be applied DHCPv6 intercommunication between
4RD CE and BNG.
Security considerations for the Diameter protocol are discussed in
[RFC6733].
7. IANA Considerations
This document requires the assignment of two new RADIUS Attributes
Types in the "Radius Types" registry (currently located at
http://www.iana.org/assignments/radius-types for the following
attributes:
o 4rd-Configuration TBD1
IANA should allocate the numbers from the standard RADIUS Attributes
space using the "IETF Review" policy [RFC5226].
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8. Acknowledgments
The authors would like to thank for valuable comments.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", RFC
2865, June 2000.
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6", RFC
3162, August 2001.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and
M. Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[RFC4301]Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC5080] Nelson, D. and DeKok A., "Common Remote Authentication Dial
In User Service (RADIUS) Implementation Issues and
Suggested Fixes", RFC 5080, December 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, May 2008.
[RFC6158] DeKok, A. and G. Weber, "RADIUS Design Guidelines", RFC
6158, March 2011.
[RFC6733] V. Fajardo, Ed., J. Arkko, J. Loughney, G. Zorn, Ed.,
"Diameter Base Protocol", RFC 6733, October 2012.
[I-D.ietf-softwire-4rd]
R. Despres, et al., "IPv4 Residual Deployment via IPv6 - a
unified Stateless Solution (4rd)", draft-ietf-softwire-4rd,
working in progress.
9.2. Informative References
[RFC2607] Aboba, B. and J. Vollbrecht, "Proxy Chaining and Policy
Implementation in Roaming", RFC 2607, June 1999.
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[RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
Extensions", RFC 2869, June 2000.
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Author's Addresses
Sheng Jiang (Editor)
Huawei Technologies Co., Ltd
Q14 Huawei Campus, 156 BeiQi Road,
ZhongGuan Cun, Hai-Dian District, Beijing 100085
P.R. China
EMail: jiangsheng@huawei.com
Yu Fu
Huawei Technologies Co., Ltd
Q14 Huawei Campus, 156 BeiQi Road,
ZhongGuan Cun, Hai-Dian District, Beijing 100085
P.R. China
EMail: eleven.fuyu@huawei.com
Bing Liu
Huawei Technologies Co., Ltd
Q14 Huawei Campus, 156 BeiQi Road,
ZhongGuan Cun, Hai-Dian District, Beijing 100085
P.R. China
EMail: leo.liubing@huawei.com
