Internet DRAFT - draft-maglione-pcp-radius-ext
draft-maglione-pcp-radius-ext
PCP WG R. Maglione
Internet-Draft Cisco Systems
Intended status: Standards Track D. Cheng
Expires: November 25, 2013 Huawei Technologies
M. Boucadair
France Telecom
May 24, 2013
RADIUS Extensions for Port Control Protocol (PCP)
draft-maglione-pcp-radius-ext-08
Abstract
This document specifies a new Remote Authentication Dial In User
Service (RADIUS) attribute to carry a Port Control Protocol (PCP)
Server Names. This attribute can be configured on a RADIUS server so
that the information can be conveyed to Network Access Server (NAS)
via RADIUS protocol, and the co-located Dynamic Host Configuration
Protocol (DHCP/DHCPv6) server can then populate the information to
PCP client.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on November 25, 2013.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PCP Server Configuration using RADIUS and DHCPv4/DHCPv6 . . . 4
4. PCP-Server-Name RADIUS Attribute . . . . . . . . . . . . . . 7
5. Table of attributes . . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Port Control Protocol (PCP) [RFC6887] provides a mechanism to control
how incoming packets are forwarded by upstream devices such as NATs
and firewalls. PCP is a client/server protocol where a PCP client
may reside on a host, a Customer Premises Equipment (CPE), etc.,
which communicates with a PCP server that may reside anywhere in a
network.
[RFC6887] defines a procedure for the PCP client to communicate with
its PCP Server. The IP address of the PCP Server(s) can be
configured to the PCP client; if not the PCP client assumes its
default router as being its PCP server.
[I-D.ietf-pcp-dhcp] defines DHCPv6 and DHCPv4 options which are meant
to be used by a PCP client to discover a PCP server name. However,
provisioning for name of the PCP server is required on a DHCPv4/
DHCPv6 server before it can populate this information.
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Auto-configuration on a DHCPv4/DHCPv6 is possible in a broadband
network, where typically, user profile is maintained on a Remote
Authentication Dial In User Service (RADIUS) server and RADIUS
protocol [RFC2865] is used to convey user-related information to
other network elements including a host and CPE. [RFC6911] describes
a typical broadband network scenario in which the Network Access
Server (NAS) acts as the access gateway for the users (hosts or CPEs)
and the NAS embeds a DHCPv6 Server function that allows it to locally
handle any DHCPv6 requests issued by the clients.
In such environment, PCP server's name can be configured on a RADIUS
server, which then passes the information to a NAS that co-locates
with the DHCPv4/DHCPv6 server, which in turn populates the location
of the PCP server.
This document defines a new RADIUS attribute that can be used to
carry a PCP server name. As defined in [I-D.ietf-pcp-dhcp], a PCP
Server Name can be a DNS name, IP literals strings, etc. This
document is designed to allow for configuring PCP Server name which
can be a DNS name, IP literals or any strings which may be passed to
a local name resolution library on the PCP client side. Multiple
occurrences of the PCP server name RADIUS attribute is supported.
The proposed RADIUS attribute is designed to accommodate various
deployment contexts (e.g., dedicated option per IP connectivity
context, single option for dual-stack access, etc.).
The approach described above is already used for providing the FQDN
of the AFTR in the DS-Lite scenario [RFC6333] and the equivalent
RADIUS attribute for the DS-Lite Tunnel Name is defined [RFC6519].
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].
The following terms are defined in [RFC6887]:
- Port forwarding
- PCP
- PCP client
- PCP Server
The following term is defined in [I-D.ietf-pcp-dhcp]:
- PCP Server Name
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3. PCP Server Configuration using RADIUS and DHCPv4/DHCPv6
Figure 1 illustrates an example of how RADIUS protocol works together
with DHCPv6, to allow a host to learn automatically the name of a PCP
server in case of a PPP session that carries IPv6 traffic.
The Network Access Server (NAS) operates as a client of RADIUS and
co-locates with a DHCPv6 Server for DHCPv6. The NAS initially sends
a RADIUS Access Request message to the RADIUS server, requesting
authentication. Once the RADIUS server receives the request, it
validates the sending client and if the request is approved, the
RADIUS server replies with an Access Accept message including a list
of attribute-value pairs that describe the parameters to be used for
this session. This list MAY also contain the name of a PCP server.
When the co-located DHCPv6 server receives a DHCPv6 message from a
client containing the PCP Server Option, it SHALL use the name
returned in the RADIUS attribute as defined in this memo to populate
the DHCPv6 PCP Server option defined in [I-D.ietf-pcp-dhcp].
PCP/DHCPv6 NAS AAA
Client DHCPv6 Server Server
| | |
|----PPP LCP Config Request------> | |
| |----Access-Request ---->|
| | |
| |<-Access-Accept---------|
| | (PCP-Server-Name) |
|<-----PPP LCP Config ACK ----- | |
| | |
|------ PPP IPv6CP Config Req ---->| |
| | |
|<----- PPP IPv6CP Config ACK -----| |
| | |
|------- DHCPv6 Solicit -------->| |
| | |
|<-------DHCPv6 Advertisement------| |
| (PCP server Name DHCPv6 Option) | |
| | |
|------- DHCPv6 Request -------->| |
| (PCP server Name DHCPv6 Option) | |
| | |
|<-------- DHCPv6 Reply --------- | |
| (PCP server Name DHCPv6 Option) | |
DHCPv6 RADIUS
Figure 1: RADIUS and DHCPv6 Message Flow for a PPP Session
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The Figure 2 illustrates how the RADIUS protocol and DHCPv6 work
together to accomplish PCP client configuration when DHCPv6 is used
to provide connectivity to a requesting host.
The difference between this message flow and previous one is that in
this scenario the interaction between NAS and AAA/ RADIUS Server is
triggered by the DHCPv6 Solicit message received by the NAS from the
DHCPv6 client, while in case of a PPP Session the trigger is the PPP
LCP Config Request message received by the NAS.
PCP/DHCPv6 NAS AAA
Client DHCPv6 Server Server
| | |
|------ DHCPv6 Solicit ---------> | |
| | |
| |----Access-Request ---->|
| | |
| |<-Access-Accept---------|
| | (PCP-Server-Name) |
| | |
|<-------DHCPv6 Advertisement------| |
| (PCP Server Name DHCPv6 Option) | |
| | |
|------- DHCPv6 Request -------->| |
| (PCP Server Name DHCPv6 Option) | |
| | |
| <-------- DHCPv6 Reply --------- | |
| (PCP Server Name DHCPv6 Option) | |
DHCPv6 RADIUS
Figure 2: RADIUS and DHCPv6 Message Flow for an IP Session
In the scenario depicted in Figure 2 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 it obtains from the previous
authentication process.
In both scenaiors mentioned above, Message-Authenticator (type 80)
according to [RFC2869] SHOULD be used to protect both Access-Request
and Access-Accept Messages.
In case that the PCP server name is re-configured, the RADIUS server
must send a RADIUS CoA message [RFC5176] that carries the RADIUS PCP
server name attribute to the NAS, which once accepts and sends back a
RADIUS CoA ACK message, the new PCP server name replaces the original
one and is then re-propulated by the DHCPv6 server.
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A similar message flow also applies to the IPv4 scenario when DHCPv4
is used to provide connectivity to the user (Figure 3).
PCP/DHCPv4 NAS AAA
Client DHCPv4 Server Server
| | |
|-------- DHCP Discovery --------> | |
| | |
| |----Access-Request ---->|
| | |
| |<-Access-Accept---------|
| | (PCP-Server-Name) |
| | |
|<--------- DHCP Offer ------------| |
| (PCP server Name Sub-Option) | |
| | |
|--------- DHCP Request -------->| |
| (PCP server Name Sub-Option) | |
| | |
| <--------- DHCP Ack -------------| |
| (PCP server Name Sub-Option) | |
DHCPv4 RADIUS
Figure 3: RADIUS and DHCPv4 Message Flow for an IP Session
After receiving the PCP server name in the initial Access-Accept the
NAS MUST store the received PCP Server Name locally. When the PCP
Client sends a DHCPv4 message to request an extension of the
lifetimes for the assigned address or prefix, the NAS does not have
to initiate a new Access-Request towards the AAA server to request
the PCP server name. The NAS retrieves the previously stored PCP
Server name and uses it in its reply.
If the DHCPv4 server to which the DHCP Renew message was sent at time
T1 has not responded, the DHCPv4 client initiates a Rebind/Reply
exchange with any available server. In this scenario the NAS MUST
initiate a new Access-Request towards the AAA server, after the co-
located DHCPv4 server receives the DHCP message. The NAS MAY include
the PCP Server Name attribute in its Access-Request.
If the NAS does not receive the PCP server name attribute in the
Access-Accept it MAY fallback to a pre-configured default tunnel
name, if any. If the NAS does not have any pre-configured default
tunnel name or if the NAS receives an Access-Reject, the PCP client
can not be configured by the NAS.
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The handling when the PCP server name is re-configured on the RADIUS
server is similar to that in IPv6 case, i.e., the new PCP server name
is conveyed to the NAS in a RADIUS CoA message, which if accepted,
the new PCP server name replaces the original one and is then re-
propulated by the DHCPv4 server.
The scenario with PPP Session and IPv4 only connectivity does not
require DHCPv4: the whole configuration of the client is performed by
PPP. This case is out of scope of this document because in order to
complete the configuration of the PCP client a new PPP IPCP option
would be required.
4. PCP-Server-Name RADIUS Attribute
A new RADIUS attribute, called PCP-Server-Name, along with its format
is defined below.
The PCP-Server-Name attribute contains a name that refers to a PCP
server the client requests to establish a connection to for PCP
related service. The NAS shall use the name(s) returned in the
RADIUS PCP-Server-Name attribute instance(s) to populate the PCP
Server Name DHCP Sub-Option in IPv4 addressing context, or the PCP
Server Name DHCPv6 Option in IPv6 addressing context, as determined
by the DHCP server [I-D.ietf-pcp-dhcp]. The same or distinct PCP
Server Names MAY be configured; it is out of scope of this document
to elaborate on this point. Nevertheless, the PCP-Server-Name
attribute conveys an indication for the deployment context.
The PCP-Server-Name attribute MAY appear in an Access-Accept packet.
This attribute MAY be used in Access-Request packets as a hint to the
RADIUS server; for example if the NAS is pre-configured with a
default PCP server name, this name MAY be inserted in the attribute.
The RADIUS server MAY ignore the hint sent by the NAS and it MAY
assign a different PCP Server name. If the NAS includes the PCP
Server Name attribute, but the AAA server does not recognize it, this
attribute MUST be ignored by the AAA Server. If the NAS does not
receive PCP Server Name attribute in the Access-Accept it MAY
fallback to a pre-configured default PCP server name, if any. If the
NAS is pre-provisioned with a default PCP server name and the PCP
server name received in Access-Accept is different from the
configured default, then the PCP server name received in the Access-
Accept message MUST be used for the session.
The PCP server Name RADIUS attribute MAY be present in Accounting-
Request records where the Acct-Status-Type is set to Start, Stop or
Interim-Update.
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The PCP server name RADIUS attribute MAY be present in an CoA-Request
packet, when the PCP server name is re-configured.
The PCP Server Name RADIUS attribute MAY appear more than once in a
message.
A summary of the PCP-Server-Name RADIUS attribute format is shown
below. The fields are transmitted from left to right.
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 | Context |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCP-Server-Name ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The description of the fields is as follows:
Type:
TBA1 for PCP-Server-Name.
Length:
This field indicates the total length in octets of this attribute
including the Type, the Length fields.
Context:
This field indicates the IP connectivity context:
0: Dual-Stack. The same option is provided for both DHCPv4 and
DHCPv6 requesting hosts.
1: This option is provided for DHCPv4 requesting hosts.
2: This option is provided for DHCPv6 requesting hosts.
PCP-Server-Name:
Includes a PCP Server Name. As defined in , PCP Server Name is a
UTF-8 [RFC3629] string that can be passed to getaddrinfo(), such
as a DNS name, address literals, etc. The name MUST NOT contain
spaces or nulls.
This attribute is type of complex [RFC6158].
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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+ 0+ 0 0 0+ TBA1 PCP-Server-Name
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.
6. Security Considerations
This document has no additional security considerations beyond those
already identified in [RFC2865].
7. IANA Considerations
This document requests the allocation of a new Radius attribute types
from the IANA registry "Radius Attribute Types" located at http://
www.iana.org/assignments/radius-types:
PCP-Server-Name - TBA1
8. Acknowledgments
The authors would like to thank Mario Ullio, Alan Dekok, Sheng Jiang
and Tassos Chatzithomaoglou for their valuable comments and
assistance.
9. References
9.1. Normative References
[I-D.ietf-pcp-dhcp]
Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
the Port Control Protocol (PCP)", draft-ietf-pcp-dhcp-07
(work in progress), March 2013.
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[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.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC5080] Nelson, D. and A. DeKok, "Common Remote Authentication
Dial In User Service (RADIUS) Implementation Issues and
Suggested Fixes", RFC 5080, December 2007.
[RFC6158] DeKok, A. and G. Weber, "RADIUS Design Guidelines", BCP
158, RFC 6158, March 2011.
[RFC6519] Maglione, R. and A. Durand, "RADIUS Extensions for Dual-
Stack Lite", RFC 6519, February 2012.
[RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
2013.
9.2. Informative References
[RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
Extensions", RFC 2869, June 2000.
[RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 5176,
January 2008.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
[RFC6911] Dec, W., Sarikaya, B., Zorn, G., Miles, D., and B.
Lourdelet, "RADIUS Attributes for IPv6 Access Networks",
RFC 6911, April 2013.
Authors' Addresses
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Roberta Maglione
Cisco Systems
181 Bay Street
Toronto, ON M5J 2T3
Canada
Email: 'robmgl@cisco.com'
Dean Cheng
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
Phone: +1 408 330 4754
Email: dean.cheng@huawei.com
Mohamed Boucadair
France Telecom
Rennes 35000
France
Email: mohamed.boucadair@orange.com
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