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Versions: 00 01 draft-ietf-sidr-bogons

Individual Submission                                          G. Huston
Internet-Draft                                              T. Manderson
Intended status: Informational                             G. Michaelson
Expires: October 24, 2008                                          APNIC
                                                          April 22, 2008


             A Profile for Bogon Origin Attestations (BOAs)
                    draft-huston-sidr-bogons-01.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
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   This Internet-Draft will expire on October 24, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2008).

Abstract

   This document defines a standard profile for Bogon Origin
   Attestations (BOAs).  A BOA is a digitally signed object that
   provides a means of verifying that an IP address block holder has not
   authorized any Autonomous System (AS) to originate routes that are
   equivalent to any of the addresses listed in the BOA, and also
   provides a means of verifying that BGP speaker is not using an AS as
   a BGP speaker without appropriate authority to use that AS.  The



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   proposed application of BOAs is intended to fit within the
   requirements for adding security measures to inter-domain routing,
   including the ability to support incremental and piecemeal deployment
   of such measures, and does not require any changes to the
   specification of BGP.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Basic Format . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Signed-Data Content Type . . . . . . . . . . . . . . . . .  4
       2.1.1.  version  . . . . . . . . . . . . . . . . . . . . . . .  4
       2.1.2.  digestAlgorithms . . . . . . . . . . . . . . . . . . .  4
       2.1.3.  encapContentInfo . . . . . . . . . . . . . . . . . . .  4
       2.1.4.  certificates . . . . . . . . . . . . . . . . . . . . .  6
       2.1.5.  crls . . . . . . . . . . . . . . . . . . . . . . . . .  6
       2.1.6.  signerInfo . . . . . . . . . . . . . . . . . . . . . .  6
   3.  BOA Validation . . . . . . . . . . . . . . . . . . . . . . . .  9
   4.  BOA Use Practices  . . . . . . . . . . . . . . . . . . . . . . 11
   5.  BOA Interpretation . . . . . . . . . . . . . . . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 12
   9.  Normative References . . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
   Intellectual Property and Copyright Statements . . . . . . . . . . 15
























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1.  Introduction

   This document defines an application of the Resource Public Key
   Infrastructure (RPKI) to validate the attestations of Internet
   Registries that certain addresses are currently neither allocated nor
   assigned to any party, and any appearance of such addresses or ASes
   in a routing advertisement in the Border Gateway Protocol (BGP)
   [RFC4271] should be considered an invalid use of such addresses or
   ASes.

   The RPKI is based on Resource Certificates.  Resource Certificates
   are X.509 certificates that conform to the PKIX profile [RFC3280],
   and to the extensions for IP addresses and AS identifiers [RFC3779].
   A Resource Certificate describes an action by an Issuer that binds a
   list of IP address blocks and Autonomous System (AS) numbers to the
   Subject of a certificate, identified by the unique association of the
   Subject's private key with the public key contained in the Resource
   Certificate.  The PKI is structured such that each current Resource
   Certificate matches a current resource allocation or assignment.
   This is described in [ID.ietf-sidr-arch].

   BOAs can be regarded as a logical opposite of a Route Origin
   Authorization (ROA) [ID.ietf-sidr-roa-format], and allows a resource
   holder to explicitly list those IP addresses and ASes that are
   denoted by the holder as not validly appearing in any routing
   advertisement, and to make this attestation in a manner that a
   relying party can validate under the framework of the RPKI.

   A BOA is a digitally signed object that makes use of Cryptographic
   Message Syntax (CMS) [RFC3852] as a standard encapsulation format.
   CMS was chosen to take advantage of existing open source software
   available for processing messages in this format.


2.  Basic Format

   Using CMS syntax, a BOA is a type of signed-data object.  The general
   format of a CMS object is:

         ContentInfo ::= SEQUENCE {
           contentType ContentType,
           content [0] EXPLICIT ANY DEFINED BY contentType }

         ContentType ::= OBJECT IDENTIFIER







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2.1.  Signed-Data Content Type

   According to the CMS specification, The signed-data content type
   shall have ASN.1 type SignedData:

         SignedData ::= SEQUENCE {
           version CMSVersion,
           digestAlgorithms DigestAlgorithmIdentifiers,
           encapContentInfo EncapsulatedContentInfo,
           certificates [0] IMPLICIT CertificateSet OPTIONAL,
           crls [1] IMPLICIT RevocationInfoChoices OPTIONAL,
           signerInfos SignerInfos }

         DigestAlgorithmIdentifiers ::= SET OF DigestAlgorithmIdentifier

         SignerInfos ::= SET OF SignerInfo

2.1.1.  version

   The version is the syntax version number.  It MUST be 3,
   corresponding to the signerInfo structure having version number 3.

2.1.2.  digestAlgorithms

   The digestAlgorithms set MUST include only SHA-256, the OID for which
   is 2.16.840.1.101.3.4.2.1.  [RFC4055] It MUST NOT contain any other
   algorithms.

2.1.3.  encapContentInfo

   encapContentInfo is the signed content, consisting of a content type
   identifier and the content itself.

         EncapsulatedContentInfo ::= SEQUENCE {
           eContentType ContentType,
           eContent [0] EXPLICIT OCTET STRING OPTIONAL }

         ContentType ::= OBJECT IDENTIFIER

2.1.3.1.  eContentType

   The ContentType for a BOA is defined as id-ct-rpkiBOA, and has the
   numerical value of 1.2.840.113549.1.9.16.1.[TBS].  [This value has to
   be assigned via an OID registration.]







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         id-smime OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
             rsadsi(113549) pkcs(1) pkcs9(9) 16 }

         id-ct OBJECT INDENTIFIER ::= { id-smime 1 }

         id-ct-rpkiBOA OBJECT IDENTIFIER ::= { id-ct [TBS] }

2.1.3.2.  eContent

   The content of a BOA identifies a list of one or more ASes and a list
   of one or more IP address prefixes that are asserted to be "bogons"
   and, accordingly, BOAs are intended to act as a constraint on the
   routing system to signal that no route object that that relates to
   these ASes or IP addresses should be interpreted as representing a
   valid routing attestation.  A BOA is formally defined as:

         id-ct-rpkiBOA ::= {
            version [0] INTEGER DEFAULT 0,
            asIDs        SEQUENCE OF asIdsOrRange,
            ipAddrBlocks SEQUENCE OF BOAIPAddressFamily }

         ASIdOrRange   ::= CHOICE {
            id               ASId,
            range            ASRange }

         ASRange       ::= SEQUENCE {
            min              ASId,
            max              ASId }

         ASId          ::= INTEGER

         BOAIPAddressFamily ::= SEQUENCE {
            addressFamily OCTET STRING (SIZE (2..3)),
            addresses SEQUENCE OF IPAddress }

         IPAddress ::= BIT STRING

2.1.3.2.1.  version

   The version number of the BogonOriginAttestation MUST be 0.

2.1.3.2.2.  asIDs

   The asIDs field contains the AS numbers that are to be regarded as
   Bogon ASes.  The set of AS numbers may be explicitly listed, or
   specified as a continuous range of values.  (See [RFC3779] for more
   details.)




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2.1.3.2.3.  BOAIPAddressFamily

   The BOAIPAddressFamily field encodes the set of IP address prefixes
   that are to be regarded as Bogon IP addresses that are to be
   constrained from appearing in any routing advertisement.  The
   intended semantics is that any route object that has the same address
   prefix as that listed as a Bogon IP address, or is a more specific
   prefix of a Bogon IP address can be regarded as a Bogon route object.

   Note that the syntax here is more restrictive than that used in the
   IP Address Delegation extension defined in RFC 3779.  That extension
   can represent arbitrary address ranges, whereas BOAs contain only
   prefixes.

   Within the BOAIPAddressFamily structure, addressFamily contains the
   Address Family Identifier (AFI) of an IP address family.  This
   specification only supports IPv4 and IPv6.  Therefore, addressFamily
   MUST be either 0001 or 0002.  The addresses field represents prefixes
   as a sequence of type IPAddress.  (See [RFC3779] for more details.)

2.1.4.  certificates

   The certificates field MAY be included.  If so, it MUST contain only
   the end entity (EE) certificate needed to validate this BOA.  In the
   use context of BOAs being made available to relying parties via
   publication in a repository system, there is no a priori requirement
   to include the EE certificate in the BOA.

2.1.5.  crls

   The crls field MUST be omitted.

2.1.6.  signerInfo

   SignerInfo is defined under CMS as:

         SignerInfo ::= SEQUENCE {
           version CMSVersion,
           sid SignerIdentifier,
           digestAlgorithm DigestAlgorithmIdentifier,
           signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL,
           signatureAlgorithm SignatureAlgorithmIdentifier,
           signature SignatureValue,
           unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL }







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2.1.6.1.  version

   The version number MUST be 3, corresponding with the choice of
   SubjectKeyIdentifier for the sid.

2.1.6.2.  sid

   The sid is defined as:

         SignerIdentifier ::= CHOICE {
           issuerAndSerialNumber IssuerAndSerialNumber,
           subjectKeyIdentifier [0] SubjectKeyIdentifier }

   For a BOA, the sid MUST be a SubjectKeyIdentifier.

2.1.6.3.  digestAlgorithm

   The digestAlgorithm MUST be SHA-256, the OID for which is
   2.16.840.1.101.3.4.2.1.  [RFC4055]

2.1.6.4.  signedAttrs

   Signed Attributes are defined as:

         SignedAttributes ::= SET SIZE (1..MAX) OF Attribute

         UnsignedAttributes ::= SET SIZE (1..MAX) OF Attribute
         Attribute ::= SEQUENCE {
           attrType OBJECT IDENTIFIER,
           attrValues SET OF AttributeValue }
         AttributeValue ::= ANY

   The signer MUST digitally sign a collection of attributes along with
   the content payload.  Each attribute in the collection MUST be DER-
   encoded.  The syntax for attributes is defined in [X.501], and the
   X.500 Directory provides a rich attribute syntax.  A very simple
   subset of this syntax is used extensively in [RFC3852], where
   ATTRIBUTE.Type and ATTRIBUTE.id are the only parts of the ATTRIBUTE
   class that are employed.

   Each of the attributes used with this CMS profile has a single
   attribute value.  Even though the syntax is defined as a SET OF
   AttributeValue, there MUST be exactly one instance of AttributeValue
   present.

   The SignedAttributes syntax within signerInfo is defined as a SET OF
   Attribute.  The SignedAttributes MUST include only one instance of
   any particular attribute.



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   The signer MUST include the content-type and message-digest
   attributes.  The signer MAY also include the signing-time signed
   attribute, the binary-signing-time signed attribute, or both signed
   attributes.  Other signed attributes that are deemed appropriate MAY
   also be included.  The intent is to allow additional signed
   attributes to be included if a future need is identified.  This does
   not cause an interoperability concern because unrecognized signed
   attributes are ignored at verification.

2.1.6.4.1.  Content-Type Attribute

         id-contentType OBJECT IDENTIFIER ::= { iso(1) member-body(2)
             us(840) rsadsi(113549) pkcs(1) pkcs9(9) 3 }

         ContentType ::= OBJECT IDENTIFIER


   A content-type attribute is required to contain the same object
   identifier as the content type contained in the
   EncapsulatedContentInfo.  The signer MUST include a content-type
   attribute containing the appropriate content type.  Section 11.1 of
   the CMS Specification [RFC3852] defines the content-type attribute.

2.1.6.4.2.  Message-Digest Attribute

         id-messageDigest OBJECT IDENTIFIER ::= { iso(1) member-body(2)
             us(840) rsadsi(113549) pkcs(1) pkcs9(9) 4 }
         MessageDigest ::= OCTET STRING

   The signer MUST include a message-digest attribute, having as its
   value the output of a one-way hash function computed on the content
   that is being signed.  Section 11.2 of the CMS Specification
   [RFC3852] defines the message-digest attribute.

2.1.6.4.3.  Signing-Time Attribute

         id-signingTime OBJECT IDENTIFIER ::= { iso(1) member-body(2)
             us(840) rsadsi(113549) pkcs(1) pkcs9(9) 5 }
         SigningTime ::= Time
         Time ::= CHOICE {
           utcTime UTCTime,
           generalizedTime GeneralizedTime }

   The signing-time attribute MAY be present in a BOA.

   The signing-time attribute specifies the time, based on the local
   system clock, at which the digital signature was applied to the
   content.  If both signing-time and binary-signing-time are present,



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   the time that is represented in both attributes MUST represent the
   same time value.  Section 11.3 of the CMS Specification [RFC3852]
   defines the content-type attribute.

2.1.6.4.4.  Binary-Signing-Time Attribute

         id-aa-binarySigningTime OBJECT IDENTIFIER ::= { iso(1)
             member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
             smime(16) aa(2) 46 }

         BinarySigningTime ::= BinaryTime

         BinaryTime ::= INTEGER (0..MAX)

   The signer MAY include a binary-signing-time attribute, specifying
   the time at which the digital signature was applied to the content.
   If both signing-time and binary-signing-time are present, the time
   that is represented in both attributes MUST represent the same time
   value.  The binary-signing-time attribute is defined in [RFC4049].

2.1.6.5.  signatureAlgorithm

   The signatureAlgorithm MUST be RSA (rsaEncryption), the OID for which
   is 1.2.840.113549.1.1.1.

2.1.6.6.  signature

   The signature value is defined as:

         SignatureValue ::= OCTET STRING

   The signature characteristics are defined by the digest and signature
   algorithms.

2.1.6.7.  unsignedAttrs

   unsignedAttrs MUST be omitted.


3.  BOA Validation

   Before a relying party can use a BOA as a constrictor of a routing
   announcement, the relying party must use the RPKI to validate the
   BOA.  To do this the relying party performs the following steps:

   1.  Verify that the BOA syntax complies with this specification.  In
       particular, verify the following:




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       A.  The eContentType of the CMS object is id-ct-rpkiBOA (OID
           1.2.840.113549.1.9.16.1.[TBS])

       B.  The version of the SignedData object is 3.

       C.  The digestAlgorithm in the SignedData object is SHA-256 (OID
           2.16.840.1.101.3.4.2.1).

       D.  The crls field in the SignedData object is omitted.

       E.  The version of the BOA is 0.

       F.  The addressFamily in the BOAIPAddressFamily is either IPv4 or
           IPv6 (0001 and 0002, respectively).

       G.  The version of the SignerInfo is 3.

       H.  The digestAlgorithm in the SignerInfo object is SHA-256 (OID
           2.16.840.1.101.3.4.2.1).

       I.  The signatureAlgorithm in the SignerInfo object is RSA (OID
           1.2.840.113549.1.1.1).

       J.  The signedAttrs field in the SignerInfo object is included.

       K.  The unsignedAttrs field in the SignerInfo object is omitted.

   2.  Obtain an EE certificate that has a Subject Key Identifier (SKI)
       that matches the sid field of the SignerInfo object.  This
       certificate may be obtained from the certificates field of the
       SignedData object (if present), the RPKI repository system, or a
       local cache.

   3.  Use the public key in the EE certificate to verify the signature
       on the BOA.

   4.  Verify that the EE certificate has an IP Address Delegation
       extension [RFC3779] and that the IP address prefix(es) in that
       extension exactly matches the IP address prefix(es) in the BOA,
       and the AS numbers in that extension exactly match the AS numbers
       in the BOA.

   5.  Verify that the EE certificate is a valid end-entity certificate
       in the resource PKI by constructing a valid certificate path to a
       trust anchor.  (See [ID.ietf-sidr-res-certs] for more details.)

   Note that requiring an exact match between the IP address prefixes
   and ASes in a BOA and the IP address prefixes and ASes in the



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   corresponding EE certificate does not place any limitations on BOA
   use.  Since each EE certificate in the RPKI architecture is used to
   verify only a single BOA, it is natural to have the IP address
   prefixes in the certificate match those in the corresponding BOA.


4.  BOA Use Practices

   BOAs are intended to allow relying parties a means of validating
   whether route origination information as described in a route
   advertisement refers to an IP address or AS number that has not been
   validly allocated for use in the routing system.

   Any party with a validly assigned Internet resource set and a CA
   certificate that described this delegation can publish a BOA,
   independently of the actions of the actions of the party that
   assigned the resource set.  BOAs are not hierarchically related.

   An Internet Registry SHOULD maintain a single BOA in relation to each
   parent registry that has assigned resources to this registry.

   An Internet Registry SHOULD maintain a regular issuance cycle for
   BOAs.

   For registries that operate on a day-to-day basis in terms of
   resource transactions, it is suggested that a local BOA management
   practice would be that a new BOA should be issued on a regular 24
   hour basis.  The corresponding EE certificate should have a validity
   period of no more than 72 hours from the time of issuance.  Each time
   a new EE certificate for a BOA is issued the previous BOA's EE
   certificate should be revoked and the previous BOA removed from the
   publication repository.

   Parties that operate a local cache of RPKI objects should ensure that
   they refresh BOA objects at intervals 24 hours to ensure that they
   have the current BOA in the local cache.


5.  BOA Interpretation

   A BOA can be used to check a route object to determine if the
   origination information in the route object refers to invalid IP
   addresses or an invalid AS number.

   If a route object has an AS origination that refers to an AS number
   that is included in a valid BOA then the route object can be regarded
   as a Bogon object, and local policies that apply to Bogon ASes can be
   applied to the object.  This holds whether or not the address prefix



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   of the route object is described by a valid ROA or not.

   If a route object has an address prefix that is equal to, or is a
   more specific prefix of an IP address that is included in a valid BOA
   then the route object can be regarded as a Bogon object, and local
   policies that apply to Bogon ASes can be applied to the object,
   unless the address prefix and AS origination of the route object is
   also described by a valid ROA, in which case the BOA is to be
   disregarded.


6.  Security Considerations

   The purpose of a BOA is to convey an attestation by an address holder
   that there is no authority for the generation of a route object that
   refers to specified addresses or origination from specified ASes.
   The integrity of a BOA must be established in order to validate the
   authority of the Bogon Attestation.  The BOA makes use of the CMS
   signed message format for integrity, and thus inherits the security
   considerations associated with that data structure.  The right of the
   BOA signer to authorize the attestation of specified IP addresses and
   ASes as Bogons is established through use of the address space and AS
   number PKI described in [ID.ietf-sidr-arch].  Specifically, a relying
   party must verify the signature on the BOA using an X.509 certificate
   issued under this PKI, and check that the prefix(es) in the BOA match
   those in the address space extension in the certificate.


7.  IANA Considerations

   [None]


8.  Acknowledgments

   The authors are indebted to the authors of Route Origin Authorization
   (ROA) [ID.ietf-sidr-roa-format], M. Lepinski, S. Kent and D. Kong, as
   much of the text used to define a BOA has been borrowed from the ROA
   format specification, and Russ Housley for clarification on the CMS
   profile.


9.  Normative References

   [ID.ietf-sidr-arch]
              Lepinski, M., Kent, S., and R. Barnes, "An Infrastructure
              to Support Secure Internet Routing", draft-ietf-sidr-arch
              (work in progress), November 2007.



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   [ID.ietf-sidr-res-certs]
              Huston, G., Michaleson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", Work in progress:
              Internet Drafts draft-ietf-sidr-res-certs-09.txt,
              November 2007.

   [ID.ietf-sidr-roa-format]
              Lepinski, M., Kent, S., and D. Kong, "An Infrastructure to
              Support Secure Internet Routing",
              draft-ietf-sidr-roa-format (work in progress), July 2007.

   [RFC3280]  Housley, R., Polk, W., Ford, W., and D. Solo, "Internet
              X.509 Public Key Infrastructure Certificate and
              Certificate Revocation List (CRL) Profile", RFC 3280,
              April 2002.

   [RFC3779]  Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
              Addresses and AS Identifiers", RFC 3779, June 2004.

   [RFC3852]  Housley, R., "Cryptographic Message Syntax (CMS)",
              RFC 3852, July 2004.

   [RFC4049]  Housley, R., "BinaryTime: An Alternate Format for
              Representing Date and Time in ASN.1", RFC 4049,
              April 2005.

   [RFC4055]  Schaad, J., Kaliski, B., and R. Housley, "Additional
              Algorithms and Identifiers for RSA Cryptography for use in
              the Internet X.509 Public Key Infrastructure Certificate
              and Certificate Revocation List (CRL) Profile", RFC 4055,
              June 2005.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [X.501]    ITU-T, "ITU-T Recommendation X.501: Information Technology
              - Open Systems interconnection - The Director Models",
              1993.


Authors' Addresses

   Geoff Huston
   Asia Pacific Network Information Centre

   Email: gih@apnic.net
   URI:   http://www.apnic.net




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   Terry Manderson
   Asia Pacific Network Information Centre

   Email: terry@apnic.net
   URI:   http://www.apnic.net


   George Michaelson
   Asia Pacific Network Information Centre

   Email: ggm@apnic.net
   URI:   http://www.apnic.net







































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Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

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Huston, et al.          Expires October 24, 2008               [Page 15]


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