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Versions: 00 01                                                         
Internet Engineering Task Force                            S. Sorce, Ed.
Internet-Draft                                                   Red Hat
Intended status: Standards Track                              T. Yu, Ed.
Expires: August 12, 2012                                T. Hardjono, Ed.
                                                 MIT Kerberos Consortium
                                                             Feb 9, 2012


                        POSIX Authorization Data
                        draft-ietf-krb-wg-pad-01

Abstract

   This document proposes a Kerberos Authorization Data element
   containing user and group directory information similar to that
   provided by RFC 2307, typically used by POSIX and POSIX-like systems
   in the course of login type activities.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 12, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Requirements Language  . . . . . . . . . . . . . . . . . . . .  3
   3.  Use-Case: Cross-Realm Directory Services . . . . . . . . . . .  3
   4.  A POSIX Authorization Structure for Kerberos V5  . . . . . . .  4
     4.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.2.  PAD-Realm  . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.3.  PAD-DNS-Domain . . . . . . . . . . . . . . . . . . . . . .  5
     4.4.  PAD-Short-Domain . . . . . . . . . . . . . . . . . . . . .  5
     4.5.  PAD-UDID . . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.6.  PAD-Posix-Username . . . . . . . . . . . . . . . . . . . .  6
     4.7.  PAD-Posix-UID  . . . . . . . . . . . . . . . . . . . . . .  6
     4.8.  PAD-Posix-GID  . . . . . . . . . . . . . . . . . . . . . .  6
     4.9.  PAD-Posix-Gecos  . . . . . . . . . . . . . . . . . . . . .  6
     4.10. PAD-Posix-Homedir  . . . . . . . . . . . . . . . . . . . .  6
     4.11. PAD-Posix-Shell  . . . . . . . . . . . . . . . . . . . . .  6
     4.12. PAD-Fullname . . . . . . . . . . . . . . . . . . . . . . .  7
     4.13. PAD-AlternateNames . . . . . . . . . . . . . . . . . . . .  7
     4.14. PAD-Groups . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.15. PAD Mapped Attributes  . . . . . . . . . . . . . . . . . .  8
     4.16. RFC2307 references for Directory Services backed KDCs  . .  8
       4.16.1.  PAD-Posix-Username as 'uid' . . . . . . . . . . . . .  8
       4.16.2.  PAD-Posix-UID as 'uidNumber'  . . . . . . . . . . . .  8
       4.16.3.  PAD-Posix-GID as 'gidNumber'  . . . . . . . . . . . .  9
       4.16.4.  PAD-Posix-Gecos as 'gecos'  . . . . . . . . . . . . .  9
       4.16.5.  PAD-Posix-Homedir as 'homeDirectory'  . . . . . . . .  9
       4.16.6.  PAD-Posix-Shell as 'loginShell' . . . . . . . . . . .  9
   5.  Validation . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   6.  Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     6.1.  PAD Format . . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  Data Structures and Extensions . . . . . . . . . . . . . . . . 11
     7.1.  AD-ID-ANCHOR . . . . . . . . . . . . . . . . . . . . . . . 11
     7.2.  AD-PAD-DATA  . . . . . . . . . . . . . . . . . . . . . . . 12
     7.3.  GSS-API Authenticator Extension  . . . . . . . . . . . . . 12
   8.  Assigned numbers . . . . . . . . . . . . . . . . . . . . . . . 13
   9.  Timeouts Considerations  . . . . . . . . . . . . . . . . . . . 13
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     13.1. Normative References . . . . . . . . . . . . . . . . . . . 14
     13.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Appendix A.  Additional Stuff  . . . . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15



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1.  Introduction

   There is an increasing need today for Kerberos to support the
   delivery and processing of authorization information pertaining to
   the principals seeking access to the servers.  Kerberos today is used
   extensively for authentication to directory services within the
   Enterprise.  In many cases, a directory service is implemented as a
   distributed database system organized across multiple realms.  As
   such, when a client in one realm seeks access to a directory service
   component located within a different realm, information regarding
   both the identity of the client and the permissions associated with
   that client must be communicated across the realms.  Currently there
   does not exist a common and standardized structure in Kerberos (V5)
   for conveying access control or authorization information.

   This draft proposes an authorization data element for Kerberos that
   contains information that is useful for dynamically updating the user
   and group directory information in a POSIX system, usually in the
   course of a login type activity.


2.  Requirements Language

   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 RFC 2119 [RFC2119].


3.  Use-Case: Cross-Realm Directory Services

   In this section we discuss one of the primary use-case scenarios for
   the POSIX Authorization Data (PAD) structure within Kerberos V5.  In
   this use-case a client principal is seeking to access a service in a
   different realm.  Since the remote service does not have
   authorization information regarding the client, it needs to obtain it
   either from querying the directory service in its own realm or the
   directory service located in the client's realm.  It is here that a
   common PAD structure becomes necessary and invaluable in order to
   achieve a high-degree of interoperability between directory services
   in distinct realms.

   In this use-case a client principal C1 in realm R1 is seeking access
   to services (or servers) located in a different realm R2.  In
   accessing local service S1 in realm R1 the client must first be
   authenticated by KDC1 in that realm.  A directory service (e.g.
   LDAP) called D1 is used in realm R1 to perform authorization of the
   client, after the client has been authenticated by KDC1.




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   When the client prinicipal later seeks to access services or
   resources S2 in realm R2, following the usual Kerberos flow the
   client must first obtain a cross-realm TGT from KDC1 (in realm R1)
   and then present it to KDC2 (in realm R2) in order to obtain a
   service-ticket for S2.  However, one immediate issue is the fact that
   service S2 does not have authorization information regarding the
   permissions or privileges of client C1 in realm R1.  The service S2
   could query its own directory service D2 to obtain authorization
   information pertaining to client C1.  In the absence of such
   information in D2, the service S2 could then perform a cross-realm
   query to the directory services D1 operating in realm R1.

   However, this cross-realm query from S2 to D1 is not only
   inefficient, but it also implies knowledge of multiple heterogenous
   systems by all actors.  Two different realms may rely on completely
   different infrastructures for user information storage, ranging from
   different LDAP implementations with different schema conventions to
   NIS, SQL databases, flat files, and so on.  Every service in the
   realm R2 would have to know what information system is in use in R1,
   how to reach it, how to read and eventually how to map data from it.
   Moreover security related aspects on the authentication of S2 by the
   directory D1, the authorization of S2 to make such a query, the
   protection of responses from D1 to S2, and so on, would have to be
   addressed.

   This use-case illustrates the need for a common PAD structure to
   address this cross-realm authorization problem.  In particular, the
   PAD structure for the cross-realm access to remote services needs to
   be contained or carried within cross-realm TGTs and service-tickets.
   Such a PAD structure needs to carry enough authorization information
   such that a decision can be made by service S2 in realm R2 regarding
   the access request originating from the client principal C1 within
   realm R1.


4.  A POSIX Authorization Structure for Kerberos V5

4.1.  Attributes

   The following attributes are defined in this document:

   o  PAD-Realm

   o  PAD-DNS-Domain

   o  PAD-Short-Domain





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   o  PAD-UDID

   o  PAD-Posix-Username

   o  PAD-Posix-UID

   o  PAD-Posix-GID

   o  PAD-Posix-Gecos

   o  PAD-Posix-Homedir

   o  PAD-Posix-Shell

   o  PAD-Fullname

   o  PAD-AlternateNames

   o  PAD-Groups

   These are each defined and discussed further below.

4.2.  PAD-Realm

   The full Realm Name of the Realm the authorization information
   applies to.

4.3.  PAD-DNS-Domain

   The DNS Domain name associated to the Realm.

4.4.  PAD-Short-Domain

   A short domain name that uniquely identifies, within the set of
   trusted realms, the domain the principal belongs to.  The short
   Domain name is useful for representation purposes in the OS.  A KDC
   MUST verify this name is unique and correctly represnt a remote realm
   within its own realm and is allowed to change or remove this field
   during validation.  This may be done to resolve name conflicts in
   large trust relationships.

4.5.  PAD-UDID

   A UDID is a Unique Domain Identifier.  Ideally it universally
   identifies the domain as the one the following local identifiers
   belongs to.  This is used to differentiate between local identifiers
   belonging to different domains/realms.




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   The UDID size can be dependent on the specific Domain type and
   imlementation.  However it SHOULD be not less than 96 bits long so
   that chances of conflicts are relatively low.  A 96 bit long
   identifier allows to construct a 128bit account identifier by
   concatenating the UDID to the local account Identifier (32bit
   quantity in POSIX).

   For the purpose of this document the UDID is a compeltely opaque
   number and implementations SHOULD not try to perform any enforcement
   on the format of this number on receiving it.

4.6.  PAD-Posix-Username

   This is the user name that correspond to the kerberos principal, this
   is the name that SHOULD be used by the OS to represent the user.  The
   OS may decide to prefix or suffix this name with the PAD-Domain or
   PAD-Realm or PAD-Short-Domain names to avoid name conflicts with
   local accounts.

4.7.  PAD-Posix-UID

   This is the UID Number associated to the user.  This number is local
   to the domain identified by PAD-UDID.

4.8.  PAD-Posix-GID

   This is the Primary GID Number associated to the user.  This number
   is local to the domain identified by PAD-UDID.

4.9.  PAD-Posix-Gecos

   The Gecos field for the User associated to the Principal if
   available.  Can be omitted.  If not available PAD-Fullname can be
   used instead.

4.10.  PAD-Posix-Homedir

   The home directory path relative to the local system, if available.
   If not available local defined defaults apply.

4.11.  PAD-Posix-Shell

   The default shell for the user, defined as the path of the binary
   relative to the local filesystem, if available.  If not available
   local defined defaults apply.






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4.12.  PAD-Fullname

   The full name of the user if available.

4.13.  PAD-AlternateNames

   Alternate names can be used by application to identify a user by
   means that differ from the user principal.  Names are in string form
   and utf8 encoded [UTF-8].  In order to allow applications to
   recognize the name type without guesswork, alternate names are
   prefixed with a string followed by the colon ':' character and the
   name, without any space or other separation character.  The following
   Alternate names are currently recognized: EMAIL, OS, OPENID, OAUTH It
   is allowed to include multiple alternate names of the same type.  The
   order in which they are provided represent the priority within the
   same name type, if applications need to choose between names.

   (TODO: need discussion on whether these needs labeled prefixes or
   explicit attributes for each alternate representation etc...)

4.14.  PAD-Groups

   This is a structured attribute and defines the groups the principal
   is member of.

   The first value in the structure represents the domain UDID and is
   optional.  If missing the domain UDID is assumed to be the one
   defined in the PAD-UDID attribute.

   Then an array of values that define the groups as follows.  Each
   group value includes 3 subvalues:

   o  (1) Name: This is the name of the group.

   o  (2) Type: Optional, type of group

   o  (3) ID: group ID.

   If the type is missing it is assumed that the group is of type "Posix
   Group" and the follwing ID is required and represents the gid number.
   The type is represented through a simplified OID like type where only
   2 levels are defined. 0.0 Is reserved for posix groups, and the 0
   prefix is reserved to official RFX use.  Additional Prefixes can be
   assigned to organizations that request it for their purposes.
   Assignment TBD.

   Multiple PAD-Groups attributes can be present at the same time.  A
   trusting KDC can augment the original user's set of groups by adding



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   a new PAD-Groups structure that contains groups local to the trusting
   domain.  In this case the domain UDID is required.  The domain UDID
   is used for gid number conflict resolution when the PAC is
   transmitted between services of different realms.

   PAD-Groups are optional attributes and the KDC, upon PAC
   revalidation, may decide to remove the original attributes that do
   not belong to the KDC security domain in order to save space or to
   censor information to avoid disclosing data to services.

4.15.  PAD Mapped Attributes

   In POSIX, users and groups ID are not universally unique, and
   different Realms (even different machines within an authorization
   realm actually) may have overlapping and conflicting IDs.  If this is
   the case, a trusting KDC may decide to re-map IDs coming from a
   foreign Realm to help services with uid/gid mapping and avoid ID
   conflicts that can lead to serious security issues.  The original IDs
   are generally preserved.

   If multiple PAD buffers are received and one of them contains a PAD-
   UDID that is recognized by the application to be the local security
   domain identifier, then only the mapped attributes in this buffer
   SHOULD be used for authorization purposes.

4.16.  RFC2307 references for Directory Services backed KDCs

   A few attributes contain the keyword 'Posix' in their name.  These
   attributes are usually represented by RFC2307 in Directory Services.
   If the primary store for these attributes is a Directory the
   following equivalence with RFC2307 defined attributes can be used.

4.16.1.  PAD-Posix-Username as 'uid'

   The PAD-Posix-Username is the User ID, and its syntax is equivalent
   to the attribute named 'uid' in RFC 2307.  This attribute is defined
   in RFC 4519 (2.39).  The attribute is defined as multivalued in RFC
   4519 but in this context only a single value is allowed.  To define
   aliases refer to the attribute PAD-AlternateNames.

4.16.2.  PAD-Posix-UID as 'uidNumber'

   The PAD-Posix-UID is the User's Unique Identifier Number, and its
   syntax is equivalent to the attribute named 'uidNumber' in RFC 2307.







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4.16.3.  PAD-Posix-GID as 'gidNumber'

   The PAD-Posix-GID is the User's Primary Group Identifier Number, and
   its syntax is equivalent to the attribute named 'gidNumber' in RFC
   2307.

4.16.4.  PAD-Posix-Gecos as 'gecos'

   The PAD-Posix-Gecos is the User's Common Name, although,
   traditionally, this field has been used to convey additional
   information beyond the user's full name.  Its syntax is equivalent to
   the attribute named 'gecos' in RFC 2307.

4.16.5.  PAD-Posix-Homedir as 'homeDirectory'

   The PAD-Posix-Homedir is the User's LOCAL home directory.  Its syntax
   is equivalent to the attribute named 'homeDirectory' in RFC 2307.

4.16.6.  PAD-Posix-Shell as 'loginShell'

   The PAD-Posix-Shell is the User's preferred login shell.  Its syntax
   is equivalent to the attribute named 'loginShell' in RFC 2307.


5.  Validation

   The PAD information is used by a client to perform authorization,
   therefore this information is highly sensitive and must be validated
   to insure no tampering has occured.

   Therefore AD-PAD elements MUST always be transmitted contained within
   an AD-CAMMAC element


6.  Encoding

   The Kerberos protocol is defined in [RFC4120] using Abstract Syntax
   Notation One (ASN.1) [X680].  As such, this specification also uses
   the ASN.1 syntax for specifying both the abstract layout of the PAD
   attributes, as well as their encodings.

6.1.  PAD Format

   The information carried in the PAD needs to be augmented by some
   identifying information in order to tie the PAD data to a specific
   identity within the Kerberos Realm.

   In order to allow additional authorization data to be tied together



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   and at the same time always verifiable we propose that the PAD is
   delivered as an AD element within a AD-CAMMAC.

   An AuthorizationData element of type AD-ID-ANCHOR is used to bind the
   PAD to the ticket and the authorization data within the PAD to the
   specific principal.  This element MUST always be present and SHOULD
   be validated.  If this element is not available the PAD data MUST be
   discarded and considered untrustworthy.

   The AD-ID-ANCHOR includes the full principal name, the realm, the
   expiration time and an optional session ID.

   The ad-type for AD-PAD-ANCHOR is (TBD).

   The AD-PAD-DATA include the attributes described in paragraph 4.

   The ad-type for AD-PAD-DATA is (TBD).

   The final structure used to deliver the PAD Data looks loosely like
   the following diagram.































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           ==AD-CAMMAC=================================
           |------------------------------------------|
           | KDC Signature (Checksum)                 |
           |------------------------------------------|
           | Service Signature (Checksum)             |
           |------------------------------------------|
           | Trusted Service Signature (Optional)     |
           |------------------------------------------|
           | Asymmetric Key KDC Signature (Optional)  |
           |------------------------------------------|
           | /-AuthorizationData SEQUENCE:----------\ |
           | |                                      | |
           | | 0:  --AD-ID-ANCHOR----               | |
           | |    | Realm            |              | |
           | |    | PrincipalName    |              | |
           | |    | expiration time  |              | |
           | |    | session ID       |              | |
           | |     ------------------               | |
           | |                                      | |
           | | 1:  --AD-PAD-DATA------              | |
           | |    | PAD Attributes ...|             | |
           | |    | ..                |             | |
           | |     -------------------              | |
           | | ....    ....                         | |
           | | X:  --AD-XXXXXXX-------              | |
           | |    | ..                |             | |
           | |     -------------------              | |
           | \--------------------------------------/ |
           ============================================




                           Figure 1: PAD Format


7.  Data Structures and Extensions

7.1.  AD-ID-ANCHOR

   The AD-ID-ANCHOR is intended to provide a means to bind data, carried
   in a AD-CAMMAC element, to a specific Identity (Principal), and
   optionally to a specific Ticket by using the session ID element.








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     AD-ID-ANCHOR            ::=SEQUENCE {
         p-realm             [0] Realm,
         p-name              [1] PrincipalName,
         expiration          [2] KerberosTime,
         session-id          [3] TBD
     }

     p-realm, p-name
        The realm and name of the principal the authorization data
        elements apply to.

     expiration
        The Expitration Date of the Authorization Data. Normally this is
        the same as the original TGT expiration date.

     session-id
        A random number that uniquely ties any following ticket this PAD
        Data is associated to with the original TGT Released to the user



7.2.  AD-PAD-DATA

   The AD-PAD-DATA data is intended to provide a means for a Kerberos
   principal credentials to carry authorization data that the receiving
   service can use to perform authorization decisions.


      AD-PAD-ANCHOR           ::=SEQUENCE {
           TBD
      }


7.3.  GSS-API Authenticator Extension

   The Authenticator Checksum as defined in RFC 4121 limit the size of
   delegated credentials in the KRB_CRED message to a size of 64KiB.

   In order to be able to transfer larger messgaes an extension is
   defined.  This extension is used in stead of the Dlght/Deleg fields,
   and the Dlght and Deleg fileds MUST not be included when this
   extensions is appended to the authenticator.









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    The extension SHALL have the following format which is drafted
    according to [draft-ietf-krb-wg-gss-cb-hash-agility]:

       Octet        Name      Description
      -----------------------------------------------------------------
       0..3         ExtN    A 16bit value identifying the extension.
                            Represented in big-endian order;
                            Contains the hex value 0xXXXXXXXX.

       4..7         Length  The length of the Extended Delegation field.
                            Represented in big-endian order;

       8..N         Data    A KRB_CRED message (N = Length + 8)



   A new flag GSS_C_EXT_DELEG_FLAG with Value X is also defined.  This
   flag is used instead of GSS_C_DELEG_FLAG when the delegated
   credentials are larger then 64KiB and cannot fit in the starndard
   Deleg field.

   Implementors SHOULD use this Extensions and this flag only if the
   KRB_CRED message is larger than 64KiB and use the standard Deleg
   field otherwise.


8.  Assigned numbers

   TBD


9.  Timeouts Considerations

   Current implementations depend on very strict timeouts on obtaining
   AS Replies.  In popular implementations the client will timeout if it
   doesn't receive a reply within 1 second.  Adding authorization data
   may involve lookups to external (to the KDC) data sources.
   Implementors should consider whether the current timeout is still
   reasonbale in light of the additional processing KDCs may be required
   to do.


10.  IANA Considerations

   TBD.






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11.  Security Considerations

   Although it is anticipated that the PAD structure itself will be
   carried within a ticket and thereby protected using the existing
   encryption methods on that ticket, there are a number of issues that
   have bearings on the security of the entire Kerberos realm as a
   whole.  Some of these issues are as follows:

   o  UID and GID Collisions: There is always the possibilty of collison
      of numbers repressing a UID and a GID.  This problem can be
      remedied to a large degree by realms using an appropriate range
      selection policy and algorithms.

   o  When collisions are detected the KDC or, alternatively, the
      receiving Service MUST be able to remap IDs so that they do not
      conflict with locally defined IDs

   o  Transit-domain issues: The PAC must be signed by the KDC that is
      attaching it to a ticket with 2 different signatures.  The service
      signature so that the service can verify its KDC validated the
      contents.  The KDC signature, so that the OS can ask the KDC to
      confirm the PAD has not been modified by a less trusted service.
      An optional asymmetric key signature is also allowed if Keys are
      available in order to avoid additional roundtrips.  For cross-
      realm tickets the "service" signature is made with the cross-realm
      key.  When a KDC receives a PAD it is allowed to modify it in any
      way.  It can filter out information or add information (like group
      memberships defined locally).  A KDC may also decide to change
      information in different ways depending on what service it is
      targeted to.


12.  Acknowledgements

   TBD.


13.  References

13.1.  Normative References

   [RFC3961]  Raeburn, K., "Encryption and Checksum Specifications for
              Kerberos 5", RFC 3961, February 2005.

   [RFC3962]  Raeburn, K., "Advanced Encryption Standard (AES)
              Encryption for Kerberos 5", RFC 3962, February 2005.

   [RFC4120]  Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The



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              Kerberos Network Authentication Service (V5)", RFC 4120,
              July 2005.

13.2.  Informative References

   [MIT-Athena]
              Steiner, J., Neuman, B., and J. Schiller, "Kerberos: An
              Authentication Service for Open Network Systems. In
              Proceedings of the Winter 1988 Usenix Conference.
              February.", 1988.

   [MS-PAC]   Microsoft, "Microsoft MS-PAC: Privilege Attribute
              Certificate Data Structure (v20100711)", July 2010.

   [POSIX]    The Open Group, "Portable Operating System Interface
              (POSIX.1-2008)", 2008.

   [RFC1510]  Kohl, J. and B. Neuman, "The Kerberos Network
              Authentication Service (V5)", RFC 1510, September 1993.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2307]  Howard, L., "An Approach for Using LDAP as a Network
              Information Service", RFC 2307, March 1998.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552,
              July 2003.

   [X.690]    ISO, "ASN.1 encoding rules: Specification of Basic
              Encoding Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER) - ITU-T Recommendation
              X.690 (ISO/IEC International Standard 8825-1:1998)", 1997.


Appendix A.  Additional Stuff

   This becomes an Appendix.


Authors' Addresses

   Simo Sorce (editor)
   Red Hat

   Email: ssorce@redhat.com




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   Tom Yu (editor)
   MIT Kerberos Consortium

   Email: tlyu@mit.edu


   Thomas Hardjono (editor)
   MIT Kerberos Consortium

   Email: hardjono@mit.edu









































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