Internet DRAFT - draft-koponen-hip-registration
draft-koponen-hip-registration
Network Working Group J. Laganier
Internet-Draft DoCoMo Euro-Labs
Expires: January 12, 2006 T. Koponen
HIIT
L. Eggert
NEC
July 11, 2005
Host Identity Protocol (HIP) Registration Extension
draft-koponen-hip-registration-01
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document specifies a registration mechanism for the Host
Identity Protocol (HIP) that allows hosts to register with services,
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such as HIP rendezvous servers or middleboxes.
1. Introduction
This document specifies an extension to the Host Identity Protocol
(HIP) [I-D.ietf-hip-arch]. The extension provides a generic means
for a host to register with a service. The service may, for example,
be a HIP rendezvous server [I-D.ietf-hip-rvs] or a middlebox
[RFC3234].
This document makes no further assumptions about the exact type of
service. Likewise, this document does not specify any mechanisms to
discover the presence of specific services or means to interact with
them after registration. Future documents may describe those
operations.
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].
2. Terminology
This section defines terminology that is used throughout the
remainder of this document. Please note that terminology shared with
other documents is defined elsewhere [I-D.ietf-hip-arch].
Requester:
a HIP node registering with a HIP registrar to request
registration for a service.
Registrar:
a HIP node offering registration for one or more services.
Service:
a facility that provides requesters with new capabilities or
functionalities operating at the HIP layer. Examples include
firewalls that support HIP traversal or HIP rendezvous servers.
Registration:
shared state stored by a requester and a registrar, allowing the
requester to benefit from one or more HIP services offered by the
registrar. Each registration has an associated finite lifetime.
Requesters can extend established registrations through re-
registration (i.e., perform a refresh).
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Registration Type:
an identifier for a given service in the registration protocol.
For example, the rendezvous service is identified by a specific
registration type.
3. HIP Registration Extension Overview
This document does not specify the means by which a requester
discovers the availability of a service, or how a requester locates a
registrar. After a requester has discovered a registrar, it either
initiates HIP base exchange or uses an existing HIP association with
the registrar. In both cases, registrars use additional parameters
that the remainder of this document defines to announce their quality
and grant or refuse registration. Requesters use corresponding
parameters to register with the service. The following sections
describe the differences between this registration handshake and the
standard HIP base exchange [I-D.ietf-hip-base] .
3.1 Registrar Announcing its Ability
A host that is capable and willing to act as a registrar SHOULD
include a REG_INFO parameter in the R1 packets it sends during all
base exchanges. If it is currently unable to provide services due to
transient conditions, it SHOULD include an empty REG_INFO, i.e., one
with no services listed. If services can be provided later, it
SHOULD send UPDATE packets indicating the current set of services
available in a new REG_INFO parameter to all hosts it is associated
with.
3.2 Requester Requesting Registration
To request registration with a service, a requester constructs and
includes a corresponding REG_REQUEST parameter in an I2 or UPDATE
packet it sends to the registrar.
If the requester has no HIP association established with the
registrar, it SHOULD already send the REG_REQUEST in the I2 packet.
This minimizes the number of packets that need to be exchanged with
the registrar. A registrar MAY end a HIP association that does not
carry a REG_REQUEST by including a NOTIFY with the type REG_REQUIRED
in the R2. In this case, no HIP association is created between the
hosts. The REG_REQUIRED notification error type is TBD.
3.3 Registrar Granting or Refusing Service(s) Registration
Once registration has been requested, the registrar is able to
authenticate the requester based on the host identity included in I2.
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It then verifies the host identity is authorized to register with the
requested service(s), based on local policies. The details of this
authorization procedure depend on the type of requested service(s)
and on the local policies of the registrar, and are therefore not
further specified in this document.
After authorization, the registrar includes in its response (i.e., an
R2 or an UPDATE, respectively, depending on whether the registration
was requested during the base exchange, or using an existing
association) a REG_RESPONSE parameter containing the service(s)
type(s) for which it has authorized registration, and zero or more
REG_FAILED parameter containing the service(s) type(s) for which it
has not authorized registration or registration has failed for other
reasons. In particular, REG_FAILED with a failure type of zero
indicates the service(s) type(s) that require further credentials for
registration.
If the registrar requires further authorization and the requester has
additional credentials available, the requester SHOULD try to again
register with the service after the HIP association has been
established.
Successful processing of a REG_RESPONSE parameter creates
registration state at the requester. In a similar manner, successful
processing of a REG_REQUEST parameter creates registration state at
the registrar and possibly at the service. Both the requester and
registrar can cancel a registration before it expires, if the
services afforded by a registration are no longer needed by the
requester, or cannot be provided any longer by the registrar (for
instance, because its configuration has changed).
+-----+ I1 +-----+-----+
| |--------------------->| | S1 |
| |<---------------------| | |
| | R1(REG_INFO:S1,S2) | +-----+
| RQ | | R | S2 |
| | I2(REG_REQ:S1) | | |
| |--------------------->| +-----+
| |<---------------------| | S3 |
| | R2(REG_RESP:S1) | | |
+-----+ +-----+-----+
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+-----+ +-----+-----+
| | UPDATE(REG_INFO:S) | | |
| |<---------------------| | |
| RQ |--------------------->| R | S |
| | UPDATE(REG_REQ:S) | | |
| | UPDATE(REG_RESP:S) | | |
| |<---------------------| | |
+-----+ +-----+-----+
4. Parameter Formats and Processing
This section describes the format and processing of the new
parameters introduced by the HIP registration extension.
4.1 Encoding Registration Lifetimes with Exponents
The HIP registration uses an exponential encoding of registration
lifetimes. This allows compact encoding of 255 different lifetime
values ranging from 4 ms to 178 days into an 8-bit integer field.
The lifetime exponent field used throughout this document MUST be
interpreted as representing the lifetime value 2^((lifetime - 64)/8)
seconds.
4.2 REG_INFO
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min Lifetime | Max Lifetime | Reg Type #1 | Reg Type #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reg Type #3 | |
+-+-+-+-+-+-+-+-+ Padding +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type [ TBD by IANA (930) ]
Length Length in octets, excluding Type, Length, and Padding.
Min Lifetime Minimum registration lifetime.
Max Lifetime Maximum registration lifetime.
Reg Type The registration types offered by the registrar.
Other documents will define specific values for registration types.
0-200 Reserved by IANA
201-255 Reserved by IANA for private use
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Registrars include the parameter in R1 packets in order to announce
their registration capabilities. The registrar SHOULD include the
parameter in UPDATE packets when its service offering has changed.
HIP_SIGNATURE_2 protects the parameter within the R1 packets.
4.3 REG_REQUEST
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime | Reg Type #1 | Reg Type #2 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type [ TBD by IANA (932) ]
Length Length in octets, excluding Type, Length, and Padding.
Lifetime Requested registration lifetime.
Reg Type The preferred registration types in order of preference.
Other documents will define specific values for registration types.
0-200 Reserved by IANA
201-255 Reserved by IANA for private use
A requester includes the REG_REQUEST parameter in I2 or UPDATE
packets to register with a registrar's service(s). If the
REG_REQUEST parameter is in an UPDATE packet, the registrar MUST NOT
modify the registrations of registration types which are not listed
in the parameter. Moreover, the requester MUST NOT include the
parameter unless the registrar's R1 packet or latest received UPDATE
packet has contained a REG_INFO parameter with the requested
registration types.
The requester MUST NOT include more than one REG_REQUEST parameter in
its I2 or UPDATE packets, while the registrar MUST be able to process
one or more REG_REQUEST parameters in received I2 or UPDATE packets.
HIP_SIGNATURE protects the parameter within the I2 and UPDATE
packets.
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4.4 REG_RESPONSE
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime | Reg Type #1 | Reg Type #2 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type [ TBD by IANA (934) ]
Length Length in octets, excluding Type, Length, and Padding.
Lifetime Granted registration lifetime.
Reg Type The granted registration types in order of preference.
Other documents will define specific values for registration types.
0-200 Reserved by IANA
201-255 Reserved by IANA for private use
The registrar SHOULD includes an REG_RESPONSE parameter in its R2 or
UPDATE packet only if a registration has successfully completed.
The registrar MUST NOT include more than one REG_RESPONSE parameter
in its R2 or UPDATE packets, while the requester MUST be able to
process one or more REG_REQUEST parameters in received R2 or UPDATE
packets.
HIP_SIGNATURE protects the parameter within the R2 and UPDATE
packets.
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4.5 REG_FAILED
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Failure Type | Reg Type #1 | Reg Type #n | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type [ TBD by IANA (936) ]
Length Length in octets, excluding Type, Length, and Padding.
Failure Type Reason for failure.
Reg Type The registration types that failed with the specified
reason.
Other documents will define specific values for registration types.
0-200 Reserved by IANA
201-255 Reserved by IANA for private use
A failure type of zero means a registrar requires additional
credentials to authorize a requester to register with the
registration types listed in the parameter. Other failure types than
zero have not been defined.
The registrar SHOULD include the REG_FAILED parameter in its R2 or
UPDATE packet, if registration with the registration types listed has
not completed successfully and a requester is asked to try again with
additional credentials.
HIP_SIGNATURE protects the parameter within the R2 and UPDATE
packets.
5. Establishing and Maintaining Registrations
Establishing and/or maintaining a registration may require additional
information not available in the transmitted REG_REQUEST or
REG_RESPONSE parameters. Therefore, registration type definitions
MAY define dependencies for HIP parameters that are not defined in
this document. Their semantics are subject to the specific
registration type specifications.
The minimum lifetime both registrars and requesters MUST support is
10 seconds, while they SHOULD support a maximum lifetime of 120
seconds, at least.
A zero lifetime is reserved for canceling purposes. Requesting a
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zero lifetime for a registration type equals to canceling the
registration of that type. A requester MAY cancel a registration
before it expires by sending a REG_REQ to the registrar with a zero
lifetime. A registrar SHOULD respond and grant a registration with a
zero lifetime. A registrar (and an attached service) MAY cancel a
registration before it expires, at its own discretion. However, if
it does so, it SHOULD send a REG_RESPONSE with a zero lifetime to all
registered requesters.
6. Security Considerations
This section discusses the threats on the HIP registration protocol,
and their implications on the overall security of HIP. In
particular, it argues that the extensions described in this document
do not introduce additional threats to HIP.
The extensions described in this document rely on the HIP base
exchange and do not modify its security characteristics, e.g.,
digital signatures or HMAC. Hence, the only threat introduced by
these extensions are related to the creation of soft registration
state at the registrar.
Registrars act on a voluntary basis and are willing to accept to be a
responder and to then create HIP associations with a number of
previously unknown hosts. Because they have to store HIP association
state anyway, adding a certain amount of time-limited HIP
registration state should not introduce and serious additional
threats, especially because HIP registrars may cancel registrations
at any time at their own discretion, e.g., because of resource
constraints during an attack.
7. IANA Considerations
This section is to be interpreted according to [RFC2434].
This document updates the IANA Registry for HIP Parameters Types by
assigning new HIP Parameter Types values for the new HIP Parameters
defined in this document:
o REG_INFO (defined in Section 4.2)
o REG_REQUEST (defined in Section 4.3)
o REG_RESPONSE (defined in Section 4.4)
o REG_FAILED (defined in Section 4.5)
IANA needs to open a new registry for registration types. No types
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are defined in this document. Adding a new type requires new IETF
specifications.
8. Acknowledgments
The following people have provided thoughtful and helpful discussions
and/or suggestions that have improved this document: Pekka Nikander,
Hannes Tschofenig and Mika Kousa.
Julien Laganier and Lars Eggert are partly funded by Ambient
Networks, a research project supported by the European Commission
under its Sixth Framework Program. The views and conclusions
contained herein are those of the authors and should not be
interpreted as necessarily representing the official policies or
endorsements, either expressed or implied, of the Ambient Networks
project or the European Commission.
9. References
9.1 Normative References
[I-D.ietf-hip-arch]
Moskowitz, R., "Host Identity Protocol Architecture",
draft-ietf-hip-arch-02 (work in progress), January 2005.
[I-D.ietf-hip-base]
Moskowitz, R., "Host Identity Protocol",
draft-ietf-hip-base-03 (work in progress), June 2005.
[I-D.ietf-hip-rvs]
Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", draft-ietf-hip-rvs-02 (work in
progress), June 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
9.2 Informative References
[RFC3234] Carpenter, B. and S. Brim, "Middleboxes: Taxonomy and
Issues", RFC 3234, February 2002.
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Authors' Addresses
Julien Laganier
DoCoMo Communications Laboratories Europe GmbH
Landsberger Strasse 312
Munich 80687
Germany
Phone: +49 89 56824 231
Email: julien.ietf@laposte.net
URI: http://www.docomolab-euro.com/
Teemu Koponen
Helsinki Institute for Information Technology
Advanced Research Unit (ARU)
P.O. Box 9800
Helsinki FIN-02015-HUT
Finland
Phone: +358 9 45 1
Email: teemu.koponen@hiit.fi
URI: http://www.hiit.fi/
Lars Eggert
NEC Network Laboratories
Kurfuerstenanlage 36
Heidelberg 69115
Germany
Phone: +49 6221 90511 43
Fax: +49 6221 90511 55
Email: lars.eggert@netlab.nec.de
URI: http://www.netlab.nec.de/
Appendix A. Document Revision History
+-----------+-------------------------------------------------------+
| Revision | Comments |
+-----------+-------------------------------------------------------+
| 00 | Initial submission. |
| 01 | Editorial and boilerplate fixes. Modified |
| | terminology. Added security considerations. Changed |
| | requirement keyword on new parameters processing. |
+-----------+-------------------------------------------------------+
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