[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 2486

     ROAMOPS Working Group                                    Bernard Aboba
     INTERNET-DRAFT                                               Microsoft
     Category: Standards Track                              Mark A. Beadles
     <draft-ietf-roamops-nai-12.txt>             WorldCom Advanced Networks
     7 November 1998
     
     
                         The Network Access Identifier
     
     
     1.  Status of this Memo
     
     This document is an Internet-Draft.  Internet-Drafts are working docu-
     ments of the Internet Engineering Task Force (IETF),  its  areas,  and
     its  working groups.  Note that other groups may also distribute work-
     ing documents as Internet-Drafts.
     
     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  mate-
     rial or to cite them other than as ``work in progress.''
     
     To  learn  the  current status of any Internet-Draft, please check the
     ``1id-abstracts.txt'' listing contained in the Internet-Drafts  Shadow
     Directories  on  ftp.ietf.org (US East Coast), nic.nordu.net (Europe),
     ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).
     
     The distribution of this memo is unlimited.  It is  filed  as  <draft-
     ietf-roamops-nai-12.txt>  and  expires  May 1, 1999.  Please send com-
     ments to the authors.
     
     
     2.  Copyright Notice
     
     Copyright (C) The Internet Society (1998).  All Rights Reserved.
     
     
     3.  Abstract
     
     In order to enhance the interoperability of roaming and tunneling ser-
     vices,  it  is desirable to have a standardized method for identifying
     users.  This document proposes syntax for the Network  Access  Identi-
     fier  (NAI), the userID submitted by the client during PPP authentica-
     tion. It is expected that this will be  of  interest  for  support  of
     roaming  as  well  as  tunneling.  "Roaming capability" may be loosely
     defined as the ability to use any one  of  multiple  Internet  service
     providers  (ISPs),  while  maintaining a formal, customer-vendor rela-
     tionship with only one.  Examples of where roaming capabilities  might
     be  required  include  ISP "confederations" and ISP-provided corporate
     network access support.
     
     
     
     
     
     
     
     Aboba & Beadles             Standards Track                   [Page 1]


     INTERNET-DRAFT       The Network Access Identifier     7 November 1998
     
     
     4.  Introduction
     
     Considerable interest has arisen recently in a set  of  features  that
     fit  within  the  general  category of "roaming capability" for dialup
     Internet users.  Interested parties have included:
     
          Regional Internet Service Providers  (ISPs)  operating  within  a
          particular  state  or  province, looking to combine their efforts
          with those of other regional providers to  offer  dialup  service
          over a wider area.
     
          National  ISPs  wishing to combine their operations with those of
          one or more ISPs in another nation to  offer  more  comprehensive
          dialup service in a group of countries or on a continent.
     
          Businesses  desiring  to  offer  their  employees a comprehensive
          package of dialup services on a global basis.  Those services may
          include  Internet  access  as  well as secure access to corporate
          intranets via a Virtual Private Network (VPN), enabled by tunnel-
          ing protocols such as PPTP, L2F, L2TP, and IPSEC tunnel mode.
     
     In order to enhance the interoperability of roaming and tunneling ser-
     vices, it is desirable to have a standardized method  for  identifying
     users.   This  document proposes syntax for the Network Access Identi-
     fier (NAI).   Examples  of  implementations  that  use  the  NAI,  and
     descriptions of its semantics, can be found in [1].
     
     
     4.1.  Terminology
     
     This document frequently uses the following terms:
     
     Network Access Identifier
               The  Network Access Identifier (NAI) is the userID submitted
               by the client during PPP  authentication.  In  roaming,  the
               purpose  of  the  NAI  is to identify the user as well as to
               assist in the routing of the authentication request.  Please
               note  that  the  NAI  may not necessarily be the same as the
               user's e-mail address or the userID submitted in an applica-
               tion layer authentication.
     
     Network Access Server
               The  Network  Access Server (NAS) is the device that clients
               dial in order to get access to the network. In  PPTP  termi-
               nology  this  is referred to as the PPTP Access Concentrator
               (PAC), and in L2TP terminology, it is  referred  to  as  the
               L2TP Access Concentrator (LAC).
     
     Roaming Capability
               Roaming  capability can be loosely defined as the ability to
               use any one of multiple Internet service  providers  (ISPs),
               while  maintaining  a  formal,  customer-vendor relationship
               with only one. Examples of cases  where  roaming  capability
               might  be  required  include  ISP  "confederations" and ISP-
     
     
     
     Aboba & Beadles             Standards Track                   [Page 2]


     INTERNET-DRAFT       The Network Access Identifier     7 November 1998
     
     
               provided corporate network access support.
     
     Tunneling Service
               A tunneling service is any network service enabled  by  tun-
               neling  protocols  such as PPTP, L2F, L2TP, and IPSEC tunnel
               mode.  One example of a tunneling service is  secure  access
               to  corporate intranets via a Virtual Private Network (VPN).
     
     
     4.2.  Requirements language
     
     In  this  document,  the  key  words  "MAY",  "MUST,    "MUST    NOT",
     "optional",  "recommended",  "SHOULD",  and  "SHOULD  NOT",  are to be
     interpreted as described in [9].
     
     
     4.3.  Purpose
     
     As described in [1], there are now a number of  services  implementing
     dialup  roaming, and the number of Internet Service Providers involved
     in roaming consortia is increasing rapidly.
     
     In order to be able to offer roaming capability, one of  the  require-
     ments is to be able to identify the user's home authentication server.
     For use in roaming, this function  is  accomplished  via  the  Network
     Access  Identifier  (NAI) submitted by the user to the NAS in the ini-
     tial PPP authentication.  It is also expected that NASes will use  the
     NAI as part of the process of opening a new tunnel, in order to deter-
     mine the tunnel endpoint.
     
     
     4.4.  Notes for Implementors
     
     As proposed in this document, the Network Access Identifier is of  the
     form  user@realm.  Please  note that while the user portion of the NAI
     conforms to the BNF described in [5], the BNF  of  the  realm  portion
     allows  the realm to begin with a digit, which is not permitted by the
     BNF described in [4]. This change was made to  reflect  current  prac-
     tice;  although  not permitted by the BNF described in [4], FQDNs such
     as 3com.com are commonly used, and accepted by current software.
     
     Please note that NAS vendors may need to modify their devices so as to
     support  the  NAI as described in this document. Devices handling NAIs
     MUST support an NAI length of at least 72 octets.
     
     
     5.  Formal definition of the NAI
     
     The  grammar for the NAI is given below, described in  ABNF  as  docu-
     mented  in  [7].   The grammar for the username is taken from [5], and
     the grammar for the realm is an updated version of [4].
     
     nai         = username / ( username "@" realm )
     
     
     
     
     Aboba & Beadles             Standards Track                   [Page 3]


     INTERNET-DRAFT       The Network Access Identifier     7 November 1998
     
     
     username    = dot-string
     
     realm       = realm "." label
     
     label       = let-dig * (ldh-str)
     
     ldh-str     = *( Alpha / Digit / "-" ) let-dig
     
     dot-string  = string / ( dot-string "." string )
     
     string      = char / ( string char )
     
     char        = c / ( "\" x )
     
     let-dig     = Alpha / Digit
     
     Alpha       = %x41-5A / %x61-7A   ; A-Z / a-z
     
     Digit       = %x30-39  ;0-9
     
     c           = < any one of the 128 ASCII characters, but
                    not any special or SP >
     
     x           = %x00-7F
                   ; all 127 ASCII characters, no exception
     
     SP          = %x20 ; Space character
     
     special     = "<" / ">" / "(" / ")" / "[" / "]" / "\" / "."
                    / "," / ";" / ":" / "@" / %x22  / Ctl
     
     Ctl         = %x00-1F / %x7F
                   ; the control characters (ASCII codes 0 through 31
                   ; inclusive and 127)
     
     Examples of valid Network Access Identifiers include:
     
          fred@3com.com
          fred@foo-9.com
          fred_smith@big-co.com
          fred=?#$&*+-/^smith@bigco.com
          fred@bigco.com
          nancy@eng.bigu.edu
          eng!nancy@bigu.edu
          eng%nancy@bigu.edu
     
     Examples of invalid Network Access Identifiers include:
     
          fred@foo
          fred@foo_9.com
          @howard.edu
          fred@bigco.com@smallco.com
          eng:nancy@bigu.edu
          eng;nancy@bigu.edu
     
     
     
     Aboba & Beadles             Standards Track                   [Page 4]


     INTERNET-DRAFT       The Network Access Identifier     7 November 1998
     
     
          <nancy>@bigu.edu
     
     
     6.  References
     
     [1]  Aboba, B., Lu J., Alsop J.,Ding J., and W. Wang, "Review of Roam-
     ing Implementations", RFC 2194, September 1997.
     
     [2]  Rigney C., Rubens A., Simpson W., and S. Willens, "Remote Authen-
     tication Dial In User Service (RADIUS)", RFC 2138, April 1997.
     
     [3]  Rigney C., "RADIUS Accounting", RFC 2139, April 1997.
     
     [4] Mockapetris, P., "Domain Names  -  Implementation  and  Specifica-
     tion", RFC 1035, November 1987.
     
     [5] Postel, J., "Simple Mail Transfer Protocol", RFC 821, August 1982.
     
     [6] Gulbrandsen A., and P. Vixie, "A DNS RR for specifying  the  loca-
     tion of services (DNS SRV)", RFC 2052, October 1996.
     
     [7] Crocker, D., and P. Overrell, "Augmented BNF for Syntax Specifica-
     tions: ABNF", RFC 2234, November 1997.
     
     [8] Atkinson, R., "Security Architecture for the  Internet  Protocol",
     RFC 1825, August 1995.
     
     [9]   Bradner,  S., "Key words for use in RFCs to Indicate Requirement
     Levels", BCP 14, RFC 2119, March 1997.
     
     
     7.  Security Considerations
     
     Since an NAI reveals the home affiliation of a user, it may assist  an
     attacker in further probing the username space. Typically this problem
     is of most concern in protocols which transmit the user name in clear-
     text across the Internet, such as in RADIUS, described in [2] and [3].
     In order to prevent snooping of the user name, protocols may use  con-
     fidentiality services provided by IPSEC, described in [8].
     
     
     8.  IANA Considerations
     
     This  document  defines  a new namespace that will need to be adminis-
     tered, namely the NAI realm namespace. In order to to  avoid  creating
     any  new  administrative  procedures,  administration of the NAI realm
     namespace will piggyback on the administration of the DNS namespace.
     
     NAI realm names are required to be unique and  the  rights  to  use  a
     given  NAI  realm  for  roaming  purposes are obtained coincident with
     acquiring the rights to use a particular fully qualified  domain  name
     (FQDN).   Those  wishing to use an NAI realm name should first acquire
     the rights to use the corresponding FQDN. Using an NAI  realm  without
     ownership  of  the  corresponding  FQDN  creates  the  possibility  of
     
     
     
     Aboba & Beadles             Standards Track                   [Page 5]


     INTERNET-DRAFT       The Network Access Identifier     7 November 1998
     
     
     conflict and therefore is to be discouraged.
     
     Note that the use of an FQDN as the realm name does not imply  use  of
     the  DNS  for location of the authentication server or for authentica-
     tion routing.  Since to date roaming has been implemented on  a  rela-
     tively small scale, existing implementations typically handle location
     of authentication servers within a domain and  perform  authentication
     routing  based  on  local  knowledge  expressed in proxy configuration
     files. The implementations described in [1] have not found a need  for
     use  of DNS for location of the authentication server within a domain,
     although this can be accomplished via  use  of  the  DNS  SRV  record,
     described  in [6].  Similarly, existing implementations have not found
     a need for dynamic routing protocols, or propagation of global routing
     information.  Note also that there is no requirement that the NAI rep-
     resent a valid email address.
     
     
     9.  Acknowledgements
     
     Thanks to Glen Zorn of Microsoft for many useful discussions  of  this
     problem space.
     
     
     10.  Authors' Addresses
     
     Bernard Aboba
     Microsoft Corporation
     One Microsoft Way
     Redmond, WA 98052
     
     Phone: 425-936-6605
     EMail: bernarda@microsoft.com
     
     Mark A. Beadles
     WorldCom Advanced Networks
     5000 Britton Rd.
     Hilliard, OH 43026
     
     Phone: 614-723-1941
     EMail: mbeadles@wcom.net
     
     
     11.  Full Copyright Statement
     
     Copyright (C) The Internet Society (1997).  All Rights Reserved.
     This  document  and  translations of it may be copied and furnished to
     others, and derivative works that comment on or otherwise  explain  it
     or  assist in its implmentation may be prepared, copied, published and
     distributed, in whole or in part, without  restriction  of  any  kind,
     provided  that  the  above  copyright  notice  and  this paragraph are
     included on all such copies and derivative works.  However, this docu-
     ment  itself  may  not be modified in any way, such as by removing the
     copyright notice or references to the Internet Society or other Inter-
     net  organizations,  except  as  needed  for the purpose of developing
     
     
     
     Aboba & Beadles             Standards Track                   [Page 6]


     INTERNET-DRAFT       The Network Access Identifier     7 November 1998
     
     
     Internet standards in which case the procedures for copyrights defined
     in  the Internet Standards process must be followed, or as required to
     translate it into languages other than English.  The  limited  permis-
     sions  granted  above  are  perpetual  and  will not be revoked by the
     Internet Society or its successors or assigns.  This document and  the
     information  contained  herein is provided on an "AS IS" basis and THE
     INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL
     WARRANTIES,  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WAR-
     RANTY THAT THE USE OF THE INFORMATION HEREIN  WILL  NOT  INFRINGE  ANY
     RIGHTS  OR  ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
     PARTICULAR PURPOSE."
     
     
     12.  Expiration Date
     
     This memo is filed as <draft-ietf-roamops-nai-12>,  and   expires  May
     1, 1999.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     Aboba & Beadles             Standards Track                   [Page 7]
     

Html markup produced by rfcmarkup 1.114, available from https://tools.ietf.org/tools/rfcmarkup/