





Network Working Group                                          C. Rigney
Request for Comments: 2866                                    Livingston
Category: Informational                                        June 2000
Obsoletes: 2139


                           RADIUS Accounting

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This document describes a protocol for carrying accounting
   information between a Network Access Server and a shared Accounting
   Server.

Implementation Note

   This memo documents the RADIUS Accounting protocol.  The early
   deployment of RADIUS Accounting was done using UDP port number 1646,
   which conflicts with the "sa-msg-port" service.  The officially
   assigned port number for RADIUS Accounting is 1813.

Table of Contents

   1.     Introduction ....................................    2
     1.1    Specification of Requirements .................    3
     1.2    Terminology ...................................    3
   2.     Operation .......................................    4
     2.1    Proxy .........................................    4
   3.     Packet Format ...................................    5
   4.     Packet Types ...................................     7
     4.1    Accounting-Request ............................    8
     4.2    Accounting-Response ...........................    9
   5.     Attributes ......................................   10
     5.1    Acct-Status-Type ..............................   12
     5.2    Acct-Delay-Time ...............................   13
     5.3    Acct-Input-Octets .............................   14
     5.4    Acct-Output-Octets ............................   15
     5.5    Acct-Session-Id ...............................   15



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     5.6    Acct-Authentic ................................   16
     5.7    Acct-Session-Time .............................   17
     5.8    Acct-Input-Packets ............................   18
     5.9    Acct-Output-Packets ...........................   18
     5.10   Acct-Terminate-Cause ..........................   19
     5.11   Acct-Multi-Session-Id .........................   21
     5.12   Acct-Link-Count ...............................   22
     5.13   Table of Attributes ...........................   23
   6.     IANA Considerations .............................   25
   7.     Security Considerations .........................   25
   8.     Change Log ......................................   25
   9.     References ......................................   26
   10.    Acknowledgements ................................   26
   11.    Chair's Address .................................   26
   12.    Author's Address ................................   27
   13.    Full Copyright Statement ........................   28

1.  Introduction

   Managing dispersed serial line and modem pools for large numbers of
   users can create the need for significant administrative support.
   Since modem pools are by definition a link to the outside world, they
   require careful attention to security, authorization and accounting.
   This can be best achieved by managing a single "database" of users,
   which allows for authentication (verifying user name and password) as
   well as configuration information detailing the type of service to
   deliver to the user (for example, SLIP, PPP, telnet, rlogin).

   The RADIUS (Remote Authentication Dial In User Service) document [2]
   specifies the RADIUS protocol used for Authentication and
   Authorization.  This memo extends the use of the RADIUS protocol to
   cover delivery of accounting information from the Network Access
   Server (NAS) to a RADIUS accounting server.

   This document obsoletes RFC 2139 [1].  A summary of the changes
   between this document and RFC 2139 is available in the "Change Log"
   appendix.

   Key features of RADIUS Accounting are:

      Client/Server Model

          A Network Access Server (NAS) operates as a client of the
          RADIUS accounting server.  The client is responsible for
          passing user accounting information to a designated RADIUS
          accounting server.





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          The RADIUS accounting server is responsible for receiving the
          accounting request and returning a response to the client
          indicating that it has successfully received the request.

          The RADIUS accounting server can act as a proxy client to
          other kinds of accounting servers.

      Network Security

          Transactions between the client and RADIUS accounting server
          are authenticated through the use of a shared secret, which is
          never sent over the network.

      Extensible Protocol

          All transactions are comprised of variable length Attribute-
          Length-Value 3-tuples.  New attribute values can be added
          without disturbing existing implementations of the protocol.

1.1.  Specification of Requirements

   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 [3].  These
   key words mean the same thing whether capitalized or not.

1.2.  Terminology

   This document uses the following terms:

   service   The NAS provides a service to the dial-in user, such as PPP
             or Telnet.

   session   Each service provided by the NAS to a dial-in user
             constitutes a session, with the beginning of the session
             defined as the point where service is first provided and
             the end of the session defined as the point where service
             is ended.  A user may have multiple sessions in parallel or
             series if the NAS supports that, with each session
             generating a separate start and stop accounting record with
             its own Acct-Session-Id.

   silently discard
             This means the implementation discards the packet without
             further processing.  The implementation SHOULD provide the
             capability of logging the error, including the contents of
             the silently discarded packet, and SHOULD record the event
             in a statistics counter.



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2.  Operation

   When a client is configured to use RADIUS Accounting, at the start of
   service delivery it will generate an Accounting Start packet
   describing the type of service being delivered and the user it is
   being delivered to, and will send that to the RADIUS Accounting
   server, which will send back an acknowledgement that the packet has
   been received.  At the end of service delivery the client will
   generate an Accounting Stop packet describing the type of service
   that was delivered and optionally statistics such as elapsed time,
   input and output octets, or input and output packets.  It will send
   that to the RADIUS Accounting server, which will send back an
   acknowledgement that the packet has been received.

   The Accounting-Request (whether for Start or Stop) is submitted to
   the RADIUS accounting server via the network. It is recommended that
   the client continue attempting to send the Accounting-Request packet
   until it receives an acknowledgement, using some form of backoff.  If
   no response is returned within a length of time, the request is re-
   sent a number of times.  The client can also forward requests to an
   alternate server or servers in the event that the primary server is
   down or unreachable.  An alternate server can be used either after a
   number of tries to the primary server fail, or in a round-robin
   fashion.  Retry and fallback algorithms are the topic of current
   research and are not specified in detail in this document.

   The RADIUS accounting server MAY make requests of other servers in
   order to satisfy the request, in which case it acts as a client.

   If the RADIUS accounting server is unable to successfully record the
   accounting packet it MUST NOT send an Accounting-Response
   acknowledgment to the client.

2.1.  Proxy

   See the "RADIUS" RFC [2] for information on Proxy RADIUS.  Proxy
   Accounting RADIUS works the same way, as illustrated by the following
   example.

   1.    The NAS sends an accounting-request to the forwarding server.

   2.    The forwarding server logs the accounting-request (if desired),
         adds its Proxy-State (if desired) after any other Proxy-State
         attributes, updates the Request Authenticator, and forwards the
         request to the remote server.






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   3.    The remote server logs the accounting-request (if desired),
         copies all Proxy-State attributes in order and unmodified from
         the request to the response packet, and sends the accounting-
         response to the forwarding server.

   4.    The forwarding server strips the last Proxy-State (if it added
         one in step 2), updates the Response Authenticator and sends
         the accounting-response to the NAS.

   A forwarding server MUST not modify existing Proxy-State or Class
   attributes present in the packet.

   A forwarding server may either perform its forwarding function in a
   pass through manner, where it sends retransmissions on as soon as it
   gets them, or it may take responsibility for retransmissions, for
   example in cases where the network link between forwarding and remote
   server has very different characteristics than the link between NAS
   and forwarding server.

   Extreme care should be used when implementing a proxy server that
   takes responsibility for retransmissions so that its retransmission
   policy is robust and scalable.

3.  Packet Format

   Exactly one RADIUS Accounting packet is encapsulated in the UDP Data
   field [4], where the UDP Destination Port field indicates 1813
   (decimal).

   When a reply is generated, the source and destination ports are
   reversed.

   This memo documents the RADIUS Accounting protocol.  The early
   deployment of RADIUS Accounting was done using UDP port number 1646,
   which conflicts with the "sa-msg-port" service.  The officially
   assigned port number for RADIUS Accounting is 1813.

   A summary of the RADIUS data format is shown below.  The fields are
   transmitted from left to right.












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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Code      |  Identifier   |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                         Authenticator                         |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Attributes ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-


   Code

      The Code field is one octet, and identifies the type of RADIUS
      packet.  When a packet is received with an invalid Code field, it
      is silently discarded.

      RADIUS Accounting Codes (decimal) are assigned as follows:

           4       Accounting-Request
           5       Accounting-Response

   Identifier

      The Identifier field is one octet, and aids in matching requests
      and replies.  The RADIUS server can detect a duplicate request if
      it has the same client source IP address and source UDP port and
      Identifier within a short span of time.

   Length

      The Length field is two octets.  It indicates the length of the
      packet including the Code, Identifier, Length, Authenticator and
      Attribute fields.  Octets outside the range of the Length field
      MUST be treated as padding and ignored on reception.  If the
      packet is shorter than the Length field indicates, it MUST be
      silently discarded.  The minimum length is 20 and maximum length
      is 4095.

   Authenticator

      The Authenticator field is sixteen (16) octets.  The most
      significant octet is transmitted first.  This value is used to
      authenticate the messages between the client and RADIUS accounting
      server.



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   Request Authenticator

      In Accounting-Request Packets, the Authenticator value is a 16
      octet MD5 [5] checksum, called the Request Authenticator.

      The NAS and RADIUS accounting server share a secret.  The Request
      Authenticator field in Accounting-Request packets contains a one-
      way MD5 hash calculated over a stream of octets consisting of the
      Code + Identifier + Length + 16 zero octets + request attributes +
      shared secret (where + indicates concatenation).  The 16 octet MD5
      hash value is stored in the Authenticator field of the
      Accounting-Request packet.

      Note that the Request Authenticator of an Accounting-Request can
      not be done the same way as the Request Authenticator of a RADIUS
      Access-Request, because there is no User-Password attribute in an
      Accounting-Request.

   Response Authenticator

      The Authenticator field in an Accounting-Response packet is called
      the Response Authenticator, and contains a one-way MD5 hash
      calculated over a stream of octets consisting of the Accounting-
      Response Code, Identifier, Length, the Request Authenticator field
      from the Accounting-Request packet being replied to, and the
      response attributes if any, followed by the shared secret.  The
      resulting 16 octet MD5 hash value is stored in the Authenticator
      field of the Accounting-Response packet.

   Attributes

      Attributes may have multiple instances, in such a case the order
      of attributes of the same type SHOULD be preserved.  The order of
      attributes of different types is not required to be preserved.

4.  Packet Types

   The RADIUS packet type is determined by the Code field in the first
   octet of the packet.












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4.1.  Accounting-Request

   Description

      Accounting-Request packets are sent from a client (typically a
      Network Access Server or its proxy) to a RADIUS accounting server,
      and convey information used to provide accounting for a service
      provided to a user.  The client transmits a RADIUS packet with the
      Code field set to 4 (Accounting-Request).

      Upon receipt of an Accounting-Request, the server MUST transmit an
      Accounting-Response reply if it successfully records the
      accounting packet, and MUST NOT transmit any reply if it fails to
      record the accounting packet.

      Any attribute valid in a RADIUS Access-Request or Access-Accept
      packet is valid in a RADIUS Accounting-Request packet, except that
      the following attributes MUST NOT be present in an Accounting-
      Request:  User-Password, CHAP-Password, Reply-Message, State.
      Either NAS-IP-Address or NAS-Identifier MUST be present in a
      RADIUS Accounting-Request.  It SHOULD contain a NAS-Port or NAS-
      Port-Type attribute or both unless the service does not involve a
      port or the NAS does not distinguish among its ports.

      If the Accounting-Request packet includes a Framed-IP-Address,
      that attribute MUST contain the IP address of the user.  If the
      Access-Accept used the special values for Framed-IP-Address
      telling the NAS to assign or negotiate an IP address for the user,
      the Framed-IP-Address (if any) in the Accounting-Request MUST
      contain the actual IP address assigned or negotiated.

   A summary of the Accounting-Request packet format is shown below.

   The fields are transmitted from left to right.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Code      |  Identifier   |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                     Request Authenticator                     |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Attributes ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-




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   Code

      4 for Accounting-Request.

   Identifier

      The Identifier field MUST be changed whenever the content of the
      Attributes field changes, and whenever a valid reply has been
      received for a previous request.  For retransmissions where the
      contents are identical, the Identifier MUST remain unchanged.

      Note that if Acct-Delay-Time is included in the attributes of an
      Accounting-Request then the Acct-Delay-Time value will be updated
      when the packet is retransmitted, changing the content of the
      Attributes field and requiring a new Identifier and Request
      Authenticator.

   Request Authenticator

      The Request Authenticator of an Accounting-Request contains a 16-octet
      MD5 hash value calculated according to the method described in
      "Request Authenticator" above.

   Attributes

      The Attributes field is variable in length, and contains a list of
      Attributes.

4.2.  Accounting-Response

   Description

      Accounting-Response packets are sent by the RADIUS accounting
      server to the client to acknowledge that the Accounting-Request
      has been received and recorded successfully.  If the Accounting-
      Request was recorded successfully then the RADIUS accounting
      server MUST transmit a packet with the Code field set to 5
      (Accounting-Response).  On reception of an Accounting-Response by
      the client, the Identifier field is matched with a pending
      Accounting-Request.  The Response Authenticator field MUST contain
      the correct response for the pending Accounting-Request.  Invalid
      packets are silently discarded.

      A RADIUS Accounting-Response is not required to have any
      attributes in it.

   A summary of the Accounting-Response packet format is shown below.
   The fields are transmitted from left to right.



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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Code      |  Identifier   |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                     Response Authenticator                    |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Attributes ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-

   Code

      5 for Accounting-Response.

   Identifier

      The Identifier field is a copy of the Identifier field of the
      Accounting-Request which caused this Accounting-Response.

   Response Authenticator

      The Response Authenticator of an Accounting-Response contains a
      16-octet MD5 hash value calculated according to the method
      described in "Response Authenticator" above.

   Attributes

      The Attributes field is variable in length, and contains a list of
      zero or more Attributes.

5.  Attributes

   RADIUS Attributes carry the specific authentication, authorization
   and accounting details for the request and response.

   Some attributes MAY be included more than once.  The effect of this
   is attribute specific, and is specified in each attribute
   description.

   The end of the list of attributes is indicated by the Length of the
   RADIUS packet.

   A summary of the attribute format is shown below.  The fields are
   transmitted from left to right.




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    0                   1                   2
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Type

      The Type field is one octet.  Up-to-date values of the RADIUS Type
      field are specified in the most recent "Assigned Numbers" RFC [6].
      Values 192-223 are reserved for experimental use, values 224-240
      are reserved for implementation-specific use, and values 241-255
      are reserved and should not be used.  This specification concerns
      the following values:

           1-39   (refer to RADIUS document [2])
          40      Acct-Status-Type
          41      Acct-Delay-Time
          42      Acct-Input-Octets
          43      Acct-Output-Octets
          44      Acct-Session-Id
          45      Acct-Authentic
          46      Acct-Session-Time
          47      Acct-Input-Packets
          48      Acct-Output-Packets
          49      Acct-Terminate-Cause
          50      Acct-Multi-Session-Id
          51      Acct-Link-Count
          60+     (refer to RADIUS document [2])

   Length

      The Length field is one octet, and indicates the length of this
      attribute including the Type, Length and Value fields.  If an
      attribute is received in an Accounting-Request with an invalid
      Length, the entire request MUST be silently discarded.

   Value

      The Value field is zero or more octets and contains information
      specific to the attribute.  The format and length of the Value
      field is determined by the Type and Length fields.

      Note that none of the types in RADIUS terminate with a NUL (hex
      00).  In particular, types "text" and "string" in RADIUS do not
      terminate with a NUL (hex 00).  The Attribute has a length field
      and does not use a terminator.  Text contains UTF-8 encoded 10646



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      [7] characters and String contains 8-bit binary data.  Servers and
      servers and clients MUST be able to deal with embedded nulls.
      RADIUS implementers using C are cautioned not to use strcpy() when
      handling strings.

      The format of the value field is one of five data types.  Note
      that type "text" is a subset of type "string."

      text     1-253 octets containing UTF-8 encoded 10646 [7]
               characters.  Text of length zero (0) MUST NOT be sent;
               omit the entire attribute instead.

      string   1-253 octets containing binary data (values 0 through 255
               decimal, inclusive).  Strings of length zero (0) MUST NOT
               be sent; omit the entire attribute instead.

      address  32 bit value, most significant octet first.

      integer  32 bit unsigned value, most significant octet first.

      time     32 bit unsigned value, most significant octet first --
               seconds since 00:00:00 UTC, January 1, 1970.  The
               standard Attributes do not use this data type but it is
               presented here for possible use in future attributes.

5.1.  Acct-Status-Type

   Description

      This attribute indicates whether this Accounting-Request marks the
      beginning of the user service (Start) or the end (Stop).

      It MAY be used by the client to mark the start of accounting (for
      example, upon booting) by specifying Accounting-On and to mark the
      end of accounting (for example, just before a scheduled reboot) by
      specifying Accounting-Off.

   A summary of the Acct-Status-Type attribute format is shown below.
   The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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   Type

      40 for Acct-Status-Type.

   Length

      6

   Value

      The Value field is four octets.

       1      Start
       2      Stop
       3      Interim-Update
       7      Accounting-On
       8      Accounting-Off
       9-14   Reserved for Tunnel Accounting
      15      Reserved for Failed

5.2.  Acct-Delay-Time

   Description

      This attribute indicates how many seconds the client has been
      trying to send this record for, and can be subtracted from the
      time of arrival on the server to find the approximate time of the
      event generating this Accounting-Request.  (Network transit time
      is ignored.)

      Note that changing the Acct-Delay-Time causes the Identifier to
      change; see the discussion under Identifier above.

   A summary of the Acct-Delay-Time attribute format is shown below.
   The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+








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   Type

      41 for Acct-Delay-Time.

   Length

      6

   Value

      The Value field is four octets.

5.3.  Acct-Input-Octets

   Description

      This attribute indicates how many octets have been received from
      the port over the course of this service being provided, and can
      only be present in Accounting-Request records where the Acct-
      Status-Type is set to Stop.

   A summary of the Acct-Input-Octets attribute format is shown below.
   The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      42 for Acct-Input-Octets.

   Length

      6

   Value

      The Value field is four octets.








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5.4.  Acct-Output-Octets

   Description

      This attribute indicates how many octets have been sent to the
      port in the course of delivering this service, and can only be
      present in Accounting-Request records where the Acct-Status-Type
      is set to Stop.

   A summary of the Acct-Output-Octets attribute format is shown below.
   The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      43 for Acct-Output-Octets.

   Length

      6

   Value

      The Value field is four octets.

5.5.  Acct-Session-Id

   Description

      This attribute is a unique Accounting ID to make it easy to match
      start and stop records in a log file.  The start and stop records
      for a given session MUST have the same Acct-Session-Id.  An
      Accounting-Request packet MUST have an Acct-Session-Id.  An
      Access-Request packet MAY have an Acct-Session-Id; if it does,
      then the NAS MUST use the same Acct-Session-Id in the Accounting-
      Request packets for that session.

      The Acct-Session-Id SHOULD contain UTF-8 encoded 10646 [7]
      characters.





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      For example, one implementation uses a string with an 8-digit
      upper case hexadecimal number, the first two digits increment on
      each reboot (wrapping every 256 reboots) and the next 6 digits
      counting from 0 for the first person logging in after a reboot up
      to 2^24-1, about 16 million.  Other encodings are possible.

   A summary of the Acct-Session-Id attribute format is shown below.
   The fields are transmitted from left to right.

    0                   1                   2
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |  Text ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      44 for Acct-Session-Id.

   Length

      >= 3

   String

      The String field SHOULD be a string of UTF-8 encoded 10646 [7]
      characters.

5.6.  Acct-Authentic

   Description

      This attribute MAY be included in an Accounting-Request to
      indicate how the user was authenticated, whether by RADIUS, the
      NAS itself, or another remote authentication protocol.  Users who
      are delivered service without being authenticated SHOULD NOT
      generate Accounting records.

   A summary of the Acct-Authentic attribute format is shown below.  The
   fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   Type

      45 for Acct-Authentic.

   Length

      6

   Value

      The Value field is four octets.

      1      RADIUS
      2      Local
      3      Remote

5.7.  Acct-Session-Time

   Description

      This attribute indicates how many seconds the user has received
      service for, and can only be present in Accounting-Request records
      where the Acct-Status-Type is set to Stop.

   A summary of the Acct-Session-Time attribute format is shown below.
   The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      46 for Acct-Session-Time.

   Length

      6

   Value

      The Value field is four octets.





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5.8.  Acct-Input-Packets

   Description

      This attribute indicates how many packets have been received from
      the port over the course of this service being provided to a
      Framed User, and can only be present in Accounting-Request records
      where the Acct-Status-Type is set to Stop.

   A summary of the Acct-Input-packets attribute format is shown below.
   The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      47 for Acct-Input-Packets.

   Length

      6

   Value

      The Value field is four octets.

5.9.  Acct-Output-Packets

   Description

      This attribute indicates how many packets have been sent to the
      port in the course of delivering this service to a Framed User,
      and can only be present in Accounting-Request records where the
      Acct-Status-Type is set to Stop.

   A summary of the Acct-Output-Packets attribute format is shown below.
   The fields are transmitted from left to right.








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    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      48 for Acct-Output-Packets.

   Length

      6

   Value

      The Value field is four octets.

5.10.  Acct-Terminate-Cause

   Description

      This attribute indicates how the session was terminated, and can
      only be present in Accounting-Request records where the Acct-
      Status-Type is set to Stop.

   A summary of the Acct-Terminate-Cause attribute format is shown
   below.  The fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+













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   Type

      49 for Acct-Terminate-Cause

   Length

      6

   Value

      The Value field is four octets, containing an integer specifying
      the cause of session termination, as follows:

      1       User Request
      2       Lost Carrier
      3       Lost Service
      4       Idle Timeout
      5       Session Timeout
      6       Admin Reset
      7       Admin Reboot
      8       Port Error
      9       NAS Error
      10      NAS Request
      11      NAS Reboot
      12      Port Unneeded
      13      Port Preempted
      14      Port Suspended
      15      Service Unavailable
      16      Callback
      17      User Error
      18      Host Request

      The termination causes are as follows:

      User Request         User requested termination of service, for
                           example with LCP Terminate or by logging out.

      Lost Carrier         DCD was dropped on the port.

      Lost Service         Service can no longer be provided; for
                           example, user's connection to a host was
                           interrupted.

      Idle Timeout         Idle timer expired.

      Session Timeout      Maximum session length timer expired.

      Admin Reset          Administrator reset the port or session.



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      Admin Reboot         Administrator is ending service on the NAS,
                           for example prior to rebooting the NAS.

      Port Error           NAS detected an error on the port which
                           required ending the session.

      NAS Error            NAS detected some error (other than on the
                           port) which required ending the session.

      NAS Request          NAS ended session for a non-error reason not
                           otherwise listed here.

      NAS Reboot           The NAS ended the session in order to reboot
                           non-administratively ("crash").

      Port Unneeded        NAS ended session because resource usage fell
                           below low-water mark (for example, if a
                           bandwidth-on-demand algorithm decided that
                           the port was no longer needed).

      Port Preempted       NAS ended session in order to allocate the
                           port to a higher priority use.

      Port Suspended       NAS ended session to suspend a virtual
                           session.

      Service Unavailable  NAS was unable to provide requested service.

      Callback             NAS is terminating current session in order
                           to perform callback for a new session.

      User Error           Input from user is in error, causing
                           termination of session.

      Host Request         Login Host terminated session normally.

5.11.  Acct-Multi-Session-Id

   Description

      This attribute is a unique Accounting ID to make it easy to link
      together multiple related sessions in a log file.  Each session
      linked together would have a unique Acct-Session-Id but the same
      Acct-Multi-Session-Id.  It is strongly recommended that the Acct-
      Multi-Session-Id contain UTF-8 encoded 10646 [7] characters.

   A summary of the Acct-Session-Id attribute format is shown below.
   The fields are transmitted from left to right.



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    0                   1                   2
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |  String ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

   50 for Acct-Multi-Session-Id.

   Length

   >= 3

   String

   The String field SHOULD contain UTF-8 encoded 10646 [7] characters.

5.12.  Acct-Link-Count

   Description

   This attribute gives the count of links which are known to have been
   in a given multilink session at the time the accounting record is
   generated.  The NAS MAY include the Acct-Link-Count attribute in any
   Accounting-Request which might have multiple links.

   A summary of the Acct-Link-Count attribute format is show below.  The
   fields are transmitted from left to right.

    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     |             Value
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              Value (cont)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+














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   Type

      51 for Acct-Link-Count.

   Length

      6

   Value

      The Value field is four octets, and contains the number of links
      seen so far in this Multilink Session.

      It may be used to make it easier for an accounting server to know
      when it has all the records for a given Multilink session.  When
      the number of Accounting-Requests received with Acct-Status-Type =
      Stop and the same Acct-Multi-Session-Id and unique Acct-Session-
      Id's equals the largest value of Acct-Link-Count seen in those
      Accounting-Requests, all Stop Accounting-Requests for that
      Multilink Session have been received.

      An example showing 8 Accounting-Requests should make things
      clearer.  For clarity only the relevant attributes are shown, but
      additional attributes containing accounting information will also
      be present in the Accounting-Request.

      Multi-Session-Id   Session-Id   Status-Type   Link-Count
      "10"               "10"         Start         1
      "10"               "11"         Start         2
      "10"               "11"         Stop          2
      "10"               "12"         Start         3
      "10"               "13"         Start         4
      "10"               "12"         Stop          4
      "10"               "13"         Stop          4
      "10"               "10"         Stop          4

5.13.  Table of Attributes

   The following table provides a guide to which attributes may be found
   in Accounting-Request packets.  No attributes should be found in
   Accounting-Response packets except Proxy-State and possibly Vendor-
   Specific.


                      #     Attribute
                      0-1   User-Name
                      0     User-Password
                      0     CHAP-Password



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                      0-1   NAS-IP-Address [Note 1]
                      0-1   NAS-Port
                      0-1   Service-Type
                      0-1   Framed-Protocol
                      0-1   Framed-IP-Address
                      0-1   Framed-IP-Netmask
                      0-1   Framed-Routing
                      0+    Filter-Id
                      0-1   Framed-MTU
                      0+    Framed-Compression
                      0+    Login-IP-Host
                      0-1   Login-Service
                      0-1   Login-TCP-Port
                      0     Reply-Message
                      0-1   Callback-Number
                      0-1   Callback-Id
                      0+    Framed-Route
                      0-1   Framed-IPX-Network
                      0     State
                      0+    Class
                      0+    Vendor-Specific
                      0-1   Session-Timeout
                      0-1   Idle-Timeout
                      0-1   Termination-Action
                      0-1   Called-Station-Id
                      0-1   Calling-Station-Id
                      0-1   NAS-Identifier [Note 1]
                      0+    Proxy-State
                      0-1   Login-LAT-Service
                      0-1   Login-LAT-Node
                      0-1   Login-LAT-Group
                      0-1   Framed-AppleTalk-Link
                      0-1   Framed-AppleTalk-Network
                      0-1   Framed-AppleTalk-Zone
                      1     Acct-Status-Type
                      0-1   Acct-Delay-Time
                      0-1   Acct-Input-Octets
                      0-1   Acct-Output-Octets
                      1     Acct-Session-Id
                      0-1   Acct-Authentic
                      0-1   Acct-Session-Time
                      0-1   Acct-Input-Packets
                      0-1   Acct-Output-Packets
                      0-1   Acct-Terminate-Cause
                      0+    Acct-Multi-Session-Id
                      0+    Acct-Link-Count
                      0     CHAP-Challenge




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                      0-1   NAS-Port-Type
                      0-1   Port-Limit
                      0-1   Login-LAT-Port

   [Note 1] An Accounting-Request MUST contain either a NAS-IP-Address
   or a NAS-Identifier (or both).

   The following table defines the above table entries.

      0     This attribute MUST NOT be present
      0+    Zero or more instances of this attribute MAY be present.
      0-1   Zero or one instance of this attribute MAY be present.
      1     Exactly one instance of this attribute MUST be present.

6.  IANA Considerations

   The Packet Type Codes, Attribute Types, and Attribute Values defined
   in this document are registered by the Internet Assigned Numbers
   Authority (IANA) from the RADIUS name spaces as described in the
   "IANA Considerations" section of RFC 2865 [2], in accordance with BCP
   26 [8].

7.  Security Considerations

   Security issues are discussed in sections concerning the
   authenticator included in accounting requests and responses, using a
   shared secret which is never sent over the network.

8.  Change Log

   US-ASCII replaced by UTF-8.

   Added notes on Proxy.

   Framed-IP-Address should contain the actual IP address of the user.

   If Acct-Session-ID was sent in an access-request, it must be used in
   the accounting-request for that session.

   New values added to Acct-Status-Type.

   Added an IANA Considerations section.

   Updated references.

   Text strings identified as a subset of string, to clarify use of
   UTF-8.




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9.  References

   [1]  Rigney, C., "RADIUS Accounting", RFC 2139, April 1997.

   [2]  Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
        Authentication Dial In User Service (RADIUS)", RFC 2865, June
        2000.

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

   [4]  Postel, J., "User Datagram Protocol", STD 6, RFC 768, August
        1980.

   [5]  Rivest, R. and S. Dusse, "The MD5 Message-Digest Algorithm", RFC
        1321, April 1992.

   [6]  Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700,
        October 1994.

   [7]  Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
        2279, January 1998.

   [8]  Alvestrand, H. and T. Narten, "Guidelines for Writing an IANA
        Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.

10.  Acknowledgements

   RADIUS and RADIUS Accounting were originally developed by Steve
   Willens of Livingston Enterprises for their PortMaster series of
   Network Access Servers.

11.  Chair's Address

   The RADIUS working group can be contacted via the current chair:

   Carl Rigney
   Livingston Enterprises
   4464 Willow Road
   Pleasanton, California  94588

   Phone: +1 925 737 2100
   EMail: cdr@telemancy.com








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12.  Author's Address

   Questions about this memo can also be directed to:

   Carl Rigney
   Livingston Enterprises
   4464 Willow Road
   Pleasanton, California  94588

   EMail: cdr@telemancy.com









































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13.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  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 implementation 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
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing 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 permissions 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 WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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