

Internet Engineering Task Force                             R. Pereira
IP Security Working Group                         TimeStep Corporation
Internet Draft                                                S. Anand
Expires in six months                            Microsoft Corporation
                                                     November 12, 1997



                   The ISAKMP Configuration Method
            <draft-ietf-ipsec-isakmp-mode-cfg-01.txt>



Status of this Memo

   This document is a submission to the IETF Internet Protocol
   Security (IPSECond) Working Group. Comments are solicited and
   should be addressed to the working group mailing list
   (ipsec@tis.com) or to the editor.

   This document is an Internet-Draft.  Internet Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
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   Distribution of this memo is unlimited.

Abstract

   This document describes a new ISAKMP method that allows
   configuration items to be set by using both push/acknowledge and
   request/reply paradigms.









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Table of Contents

   1. Introduction...................................................2
     1.1. Specification of Requirements..............................2
   2. Configuration Method...........................................3
   3. Configuration Transaction......................................3
     3.1. Configuration NOTIFY Codes.................................4
   4. Configuration NOTIFY Data......................................4
   5. Configuration Attributes.......................................4
   6. Security Considerations........................................5
   7. References.....................................................5
   8. Acknowledgments................................................6
   9. Editors' Addresses.............................................6



1.   Introduction

   ISAKMP provides a framework to negotiate and derive Security
   Associations.  But since it is used within the IPSec framework, it
   may also be used to configure secure hosts.  This configuration may
   take place between a gateway, an end-host client, or a
   configuration manager.  For example, this can be used to configure
   multi-protocol IP tunnels securely.

   It is assumed that the reader is familiar with the terms and
   concepts described in the "Security Architecture for the Internet
   Protocol" [Atkinson95] and "IP Security Document Roadmap"
   [Thayer97] documents.

   Readers are advised to be familiar with both [Harkins97] and
   [ISAKMP] because of the terminology used within this document and
   the fact that this document is an extension of both of those
   documents.


1.1. Specification of Requirements

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD
   NOT", and "MAY" that appear in this document are to be interpreted
   as described in [Bradner97].










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2.   Configuration Method

   Configuration Method uses an exchange mode type of InfoMode for the
   ISAKMP header.  This mode SHOULD NOT be used prior to the
   establishment of an ISAKMP Phase 1 Security Association.

   The InfoMode exchange used to transport configuration items uses
   the exact format as defined in [Harkins97] under "ISAKMP
   Information Exchanges".

   Thus if there is an ISAKMP SA already established between the
   peers, then the message will be sent out encrypted and
   authentication.


3.   Configuration Transaction

   A "Configuration Transaction" is defined as two Configuration Mode
   exchanges, the first being either a Set or a Request and the second
   being either a Acknowledge or a Reply respectively.  The Message ID
   within the ISAKMP header identifies the configuration transaction
   and MUST NOT be zero.

   There are two paradigms to follow for this mode.

   o "Set/Acknowledge" works on the push principle that allows a
     configuration manager (a host that wishes to send information to
     another) to start the configuration transaction.  The
     Acknowledge code MUST return zero length attributes that it
     accepted.  Those attributes that it did not accept will NOT be
     sent back in the acknowledgement.

   o "Request/Reply" allows a host to request information from an
     informed host (a configuration manager).  Attributes in the
     Request exchange may have values filled in to request these
     values once again.  The Reply exchange MAY wish to choose those
     values, or return new values.  It MAY also add new attributes
     and not include some requested attributes.

   Transactions are completed once the Reply or Acknowledge code is
   received.  If one is not received, the implementation MAY wish to
   retransmit the original exchange.

   If a badly formatted exchange is received, the message SHOULD be
   silently discarded and perhaps logged locally, as per local policy.
   Badly formatted exchanges MIGHT also include those with unknown
   codes or unknown attributes within the Configuration Method.





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3.1. Configuration NOTIFY Codes

    Code                       Value
   ========================== ===========
    ISKAMP_CFG_REQUEST         101
    ISKAMP_CFG_REPLY           102
    ISKAMP_CFG_SET             103
    ISKAMP_CFG_ACK             104

   Since the Configuration Method uses NOTIFY codes for information
   exchange, if the peer does not support this, it will quietly
   discard the message without breaking any SA negotiation.


4.   Configuration NOTIFY Data

   The data of the NOTIFY payload that contains the configuration
   information is a set of ISAKMP attributes [ISAKMP].


5.   Configuration Attributes

    Attribute                  Value   Type             Length
   ========================== ======= ================ ============
    INTERNAL_IP4_ADDRESS       1       Variable         4 octets
    INTERNAL_IPX_ADDRESS       2       Variable         6 octets
    INTERNAL_NB_ADDRESS        3       Variable         16 octets
    INTERNAL_IP4_DNS           4       Variable         4 octets
    INTERNAL_IP4_NBNS          5       Variable         4 octets
    RENEW_SECONDS              6       Basic/Variable   2 or 4 octets
    USE_IP4_DHCP               7       Variable         4 octets

   o INTERNAL_IP4_ADDRESS - Specifies an IPv4 address within the
     internal network.  This address is sometimes called a red node
     address.  This address is sometimes an illegal address on the
     Internet.

   o INTERNAL_IPX_ADDRESS - Specifies an IPX address within the
     internal network.

   o INTERNAL_NB_ADDRESS - Specifies a NetBios address within the
     internal network.

   o INTERNAL_IP4_DNS - Specifies an IPv4 address of a DNS server
     within the network.

   o INTERNAL_IP4_NBNS - Specifies an IPv4 address of a NetBios Name
     Server (WINS) within the network.





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   o RENEW_SECONDS - Specifies the number of seconds that the host
     can use all of the information set within the configuration
     transaction.  The host MUST renew this information before this
     expiry time and MUST not use any of the information obtained
     through the configuration transaction after the expiry time.

   o USE_IP4_DHCP - Instructs the host to request any subsequent
     information through the DHCP protocol.  This attribute holds the
     IPv4 address of a DHCP server.

   It is hoped that more attribute types will be defined in the
   future.  Some suggestions would be to distribute local policy, or
   even authentication certificates.  Also, note that no
   recommendations are made to how an implementation actually figures
   out what information to send.  i.e. we do not recommend any
   specific method of (a gateway) determining which DNS server should
   be returned to a requesting host.


6.   Security Considerations

  This entire draft discusses a new ISAKMP configuration method to
  allow entities in the network to acquire and share configuration
  information.

  The draft mandates that this exchange should usually occur after
  the Phase I Security Association has been set up and that the
  entire exchange be protected by the Phase I SA.  Thus the exchange
  is as secure as any Phase II SA.


7.   References

   [Atkinson95] Atkinson, R., "Security Architecture for the Internet
   Protocol", draft-ietf-ipsec-arch-sec-01

   [Bradner97] Bradner, S., "Key words for use in RFCs to indicate
   Requirement Levels", RFC2119, March 1997

   [ISAKMP] D. Maughan, M. Schertler, M. Schneider, J. Turner,
   "Internet Security Association and Key Management Protocol",
   draft-ietf-ipsec-isakmp-08

   [Harkins97] D. Harkins, "The Resolution of ISAKMP and Oakley",
   draft-ietf-ipsec-isakmp-oakley-05

   [Thayer97] R. Thayer, N. Doraswamy, R. Glenn, "IP Security Document
   Roadmap", draft-ietf-ipsec-doc-roadmap-00




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8.   Acknowledgments

   The editors would like to thank Peter Ford of Microsoft and Bob
   Moskowitz of Chrysler.


9.   Editors' Addresses

     Roy Pereira
     rpereira@timestep.com
     TimeStep Corporation
     +1 (613) 599-3610 x 4808

     Sanjay Anand
     sanjayan@microsoft.com
     Microsoft Corporation
     +1 (206) 936-6367


   The IPSec working group can be contacted via the IPSec working
   group's mailing list (ipsec@tis.com) or through its chairs:

     Robert Moskowitz
     rgm@chrysler.com
     Chrysler Corporation

     Theodore Y. Ts'o
     tytso@MIT.EDU
     Massachusetts Institute of Technology























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