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Versions: (draft-dekok-radext-radius-extensions) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RFC 6929

Network Working Group                                         Alan DeKok
INTERNET-DRAFT                                            Network RADIUS
Category: Proposed Standard                                     Avi Lior
Updates: 2865, 2866, 5176                                            BWS
<draft-ietf-radext-radius-extensions-02.txt>
Expires: January 6, 2012
25 October 2011



      Remote Authentication Dial In User Service (RADIUS) Protocol
                               Extensions
               draft-ietf-radext-radius-extensions-02.txt

Abstract

   The Remote Authentication Dial In User Service (RADIUS) protocol is
   nearing exhaustion of its current 8-bit attribute type space.  In
   addition, experience shows a growing need for complex grouping, along
   with attributes which can carry more than 253 octets of data.  This
   document defines changes to RADIUS which address all of the above
   problems.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working 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
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on January 6, 2012.

Copyright Notice




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   Copyright (c) 2011 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
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.







































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Table of Contents

1.  Introduction .............................................    5
   1.1.  Terminology .........................................    6
   1.2.  Requirements Language ...............................    6
2.  Extensions to RADIUS .....................................    8
   2.1.  Extended Type .......................................    8
   2.2.  Extended Type with Flags ............................    9
   2.3.  TLV Data Type .......................................   11
      2.3.1.  TLV Nesting ....................................   13
   2.4.  EVS Data Type .......................................   13
   2.5.  Integer64 Data Type .................................   15
   2.6.  Attribute Naming and Type Identifiers ...............   15
      2.6.1.  Attribute and TLV Naming .......................   16
      2.6.2.  Attribute Type Identifiers .....................   16
      2.6.3.  TLV Identifiers ................................   16
      2.6.4.  VSA Identifiers ................................   17
3.  Attribute Definitions ....................................   18
   3.1.  Extended-Type-1 .....................................   18
   3.2.  Extended-Type-2 .....................................   19
   3.3.  Extended-Type-3 .....................................   20
   3.4.  Extended-Type-4 .....................................   21
   3.5.  Extended-Type-Flagged-1 .............................   21
   3.6.  Extended-Type-Flagged-2 .............................   23
4.  Vendor Specific Attributes ...............................   24
   4.1.  Extended-Vendor-Specific-1 ..........................   24
   4.2.  Extended-Vendor-Specific-2 ..........................   25
   4.3.  Extended-Vendor-Specific-3 ..........................   26
   4.4.  Extended-Vendor-Specific-4 ..........................   28
   4.5.  Extended-Vendor-Specific-5 ..........................   29
   4.6.  Extended-Vendor-Specific-6 ..........................   30
5.  Compatibility with traditional RADIUS ....................   32
   5.1.  Attribute Allocation ................................   32
   5.2.  Proxy Servers .......................................   33
6.  Guidelines ...............................................   34
   6.1.  Updates to RFC 6158 .................................   34
   6.2.  Guidelines For the New Types ........................   34
   6.3.  Allocation Request Guidelines .......................   34
   6.4.  TLV Guidelines ......................................   35
   6.5.  Implementation Guidelines ...........................   36
   6.6.  Vendor Guidelines ...................................   36
7.  Rationale ................................................   36
   7.1.  Attribute Audit .....................................   37
8.  Examples .................................................   37
   8.1.  Extended Type .......................................   38
   8.2.  Extended Type with Flags ............................   40
9.  IANA Considerations ......................................   42
   9.1.  Attribute Allocations ...............................   42



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   9.2.  RADIUS Attribute Type Tree ..........................   43
   9.3.  Extending the Attribute Type Tree ...................   44
10.  Security Considerations .................................   44
11.  References ..............................................   44
   11.1.  Normative references ...............................   44
   11.2.  Informative references .............................   45
Appendix A - Extended Attribute Generator Program ............   46












































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1.  Introduction

   Under current allocation pressure, we expect that the RADIUS
   Attribute Type space will be exhausted by 2014 or 2015.  We therefore
   need a way to extend the type space, so that new specifications may
   continue to be developed.  Other issues have also been shown with
   RADIUS.  The attribute grouping method defined in [RFC2868] has been
   shown to be imnpractical, and a more powerful mechanism is needed.
   Multiple attributes have been defined which transport more than the
   253 octets of data originally envisioned with the protocol.  Each of
   these attributes is handled as a "special case" inside of RADIUS
   implementations, instead of as a general method.  We therefore also
   need a standardized method of transporting large quantities of data.
   Finally, some vendors are close to allocating all of the Attributes
   within their Vendor-Specific Attribute space.  It would be useful to
   leverage changes to the base protocol for extending the Vendor-
   Specific Attribute space.

   We satisfy all of these requirements through the following
   modifications to RADIUS:

   * defining an "Extended Type" format, which adds 8 bits of "Extended
     Type" to the RADIUS Attribute Type space, by using one octet of the
     "Value" field.  This method gives us a general way of extending
     the Attribute Type Space.

   * allocating 4 attributes as using the format of "Extended Type".
     This allocation extends the RADIUS Attribute Type Space by
     approximately 1000 values.

   * defining an "Extended Type with Flags" format, which inserts
     an additional "Flags" octet between the "Extended Type" octet,
     and the "Value" field.  This method gives us a general way of
     adding additional functionality to the protocol.

   * defining a method which uses the "Flags" field to indicate data
     fragmentation across multiple Attributes.  This method provides a
     standard way for an Attribute to carry more than 253 octets of
     data.

   * allocating 2 attributes as using the format of "Extended Type with
     Flags".  This allocation extends the RADIUS Attribute Type Space
     by an additional 500 values.

   * defining a new "Type Length Value" (TLV) data type.  The data type
     allows an attribute to carry TLVs as "sub-attributes", which can in
     turn encapsulate other TLVs as "sub-sub-attributes."  This change
     creates a standard way to group a set of Attributes.



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   * defining a new "extended Vendor-Specific" (EVS) data type.  The
     data type allows an attribute to carry Vendor-Specific Attributes
     (VSAs) inside of the new attribute formats.

   * defining a new "integer64" data type.  The data type allows
     counters which track more than 2^32 octets of data.

   * allocating 6 attributes using the new EVS data type.  This
     allocation extends the Vendor-Specific Attribute type space by
     over 1500 values.

   As with any protocol change, the changes defined here are the result
   of a series of compromises.  We have tried to find a balance between
   flexibility, space in the RADIUS message, compatibility with existing
   deployments, and implementation difficulty.

1.1.  Terminology

   This document uses the following terms:

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


invalid attribute
     This means that the Length field of an Attribute is valid (as per
     [RFC2865], Section 5, top of page 25).  However, the Value field of
     the attribute does not follow the format required by the data type
     defined for that Attribute.  e.g. an Attribute of type "address"
     which encapsulates more than four, or less than four, octets of
     data.

1.2.  Requirements Language

   In this document, several words are used to signify the requirements
   of the specification.  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
   [RFC2119].

   An implementation is not compliant if it fails to satisfy one or more
   of the must or must not requirements for the protocols it implements.
   An implementation that satisfies all the MUST, MUST NOT, SHOULD, and
   SHOULD NOT requirements for its protocols is said to be
   "unconditionally compliant"; one that satisfies all the MUST and MUST



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   NOT requirements but not all the SHOULD or SHOULD NOT requirements
   for its protocols is said to be "conditionally compliant".

















































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2.  Extensions to RADIUS

   This section defines two new attribute formats; "Extended Type"; and
   "Extended Type with Flags".  The formats are defined below.

2.1.  Extended Type

   This section defines a new attribute format, called "Extended Type".
   A summary of the 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     | Extended-Type |  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      This field is identical to the Type field of the Attribute format
      defined in [RFC2865] Section 5.

   Length

      This field is identical to the Length field of the Attribute
      format defined in [RFC2865] Section 5.  Permitted values are
      between 4 and 255.  If a client or server receives an Extended
      Attribute with a Length of 2 or 3, then that Attribute MUST be
      deemed to be an "invalid attribute", it SHOULD be silently
      discarded.  If it is not discarded, it MUST NOT be handled in the
      same manner as a well-formed attribute.

      Note that an "invalid attribute" does not cause the entire packet
      to be discarded, or to be treated as a negative acknowledgement.
      Instead, only the "invalid attribute" is discarded.

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA.  Unlike the Type field defined in
      [RFC2865] Section 5, no values are allocated for experimental or
      implementation-specific use.  Values 241-255 are reserved and
      SHOULD NOT be used.

      The Extended-Type is meaningful only within a context defined by
      the Type field.  That is, this field may be thought of as defining
      a new type space of the form "Type.Extended-Type".  See Section
      2.5, below, for additional discussion.



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      A RADIUS server MAY ignore Attributes with an unknown
      "Type.Extended-Type".

      A RADIUS client MAY ignore Attributes with an unknown
      "Type.Extended-Type".

   Value

      This field is similar to the Value field of the Attribute format
      defined in [RFC2865] Section 5.  The format of the data SHOULD be
      a valid RADIUS data type.

      The addition of the Extended-Type field decreases the maximum
      length for attributes of type "text" or "string" from 253 to 252
      octets.  Where an Attribute needs to carry more than 252 octets of
      data, the "Extended Type with flags" format should be used.

   Experience has shown that the "experimental" and "implementation
   specific" attributes defined in [RFC2865] Section 5 have had little
   practical value.  We therefore do not continue that practice here
   with the Extended-Type field.

2.2.  Extended Type with Flags

   This section defines a new attribute format, called "Extended Type
   with Flags".  It leverages the "Extended Type" format in order to
   permit the transport of attributes encapsulating more than 253 octets
   of data.  A summary of the 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     | Extended-Type |M|   Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      This field is identical to the Type field of the Attribute format
      defined in [RFC2865] Section 5.

   Length

      This field is identical to the Length field of the Attribute
      format defined in [RFC2865] Section 5.  Permitted values are
      between 5 and 255.  If a client or server receives an "Extended



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      Attribute with Flags" with a Length of 2, 3, or 4, then that
      Attribute MUST be deemed to be an "invalid attribute", it SHOULD
      be silently discarded.  If it is not discarded, it MUST NOT be
      handled in the same manner as a well-formed attribute.

      Note that an "invalid attribute" does not cause the entire packet
      to be discarded, or to be treated as a negative acknowledgement.
      Instead, only the "invalid attribute" is discarded.

   Extended-Type

      This field is identical to the Extended-Type field defined above
      in Section 2.1.

   M (More)

      The More Flag is one (1) bit in length, and indicates whether or
      not the current attribute contains "more" than 251 octets of data.
      The More flag MUST be clear (0) if the Length field has value less
      than 255.  The More flag MAY be set (1) if the Length field has
      value of 255.

      If the More flag is set (1), it indicates that the Value field has
      been fragmented across multiple RADIUS attributes.  When the More
      flag is set (1), the attribute SHOULD have a Length field of value
      255; it MUST NOT have a length Field of of value 4; there MUST be
      an attribute following this one; and the next attribute MUST have
      both the same Type and Extended Type.  That is, multiple fragments
      of the same value MUST be in order and MUST be consecutive
      attributes in the packet, and the last attribute in a packet MUST
      NOT have the More flag set (1).

      When the Length field of an attribute has value less than 255, the
      More flag SHOULD be clear (0).

      If a client or server receives an attribute fragment with the
      "More" flag set (1), but for which no subsequent fragment can be
      found, then the fragmented attribute is deemed to be an "invalid
      attribute" and the entire set of fragments SHOULD be silently
      discarded.  If the fragmented attribute is not discarded, it MUST
      NOT be handled in the same manner as a well-formed attribute.

   Flags

      This field is 7 bits long, and is reserved for future use.
      Implementations MUST set it to zero (0) when encoding an attribute
      for sending in a packet.  The contents SHOULD be ignored on
      reception.



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   Value

      This field is similar to the Value field of the Attribute format
      defined in [RFC2865] Section 5.  It may contain a complete set of
      data (when the Length field has value less than 255), or it may
      contain a fragment of data (when the More field is set).

      Any interpretation of the resulting data MUST occur after the
      fragments have been reassembled.  The length of the data MUST be
      taken as the sum of the lengths of the fragments (i.e. Value
      fields) from which it is constructed.  The format of the data
      SHOULD be a valid RADIUS data type.

   This definition increases the RADIUS Attribute Type space as above,
   but also provides for transport of Attributes which could contain
   more than 253 octets of data.

2.3.  TLV Data Type

   We define a new data type in RADIUS, called "tlv".  The "tlv" data
   type is an encapsulation layer which which permits the "Value" field
   of an Attribute to contain new sub-Attributes.  These sub-Attributes
   can in turn contain "Value"s of data type TLV.  This capability both
   extends the attribute space, and permits "nested" attributes to be
   used.  This nesting can be used to encapsulate or group data into one
   or more logical containers.

   The "tlv" data type re-uses the RADIUS attribute format, as given
   below:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   TLV-Type    |  TLV-Length   |     TLV-Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   TLV-Type

      The Type field is one octet.  Up-to-date values of this field are
      specified by IANA.  Values of zero (0) MUST NOT be used.  Values
      254-255 are "Reserved" for use by future extensions to RADIUS.
      The value 26 has no special meaning.

      As with Extended-Type above, the TLV-Type is meaningful only
      within a context defined by "Type" fields of the encapsulating
      Attributes.  That is, the field may be thought of as defining a
      new type space of the form "Type.Extended-Type.TLV-Type".  Where
      TLVs are nested, the type space is of the form "Type.Extended-



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      Type.TLV-Type.TLV-Type", etc.

      A RADIUS server MAY ignore Attributes with an unknown "TLV-Type".

      A RADIUS client MAY ignore Attributes with an unknown "TLV-Type".

   TLV-Length

      The TLV-Length field is one octet, and indicates the length of
      this TLV including the TLV-Type, TLV-Length and TLV-Value fields.
      It MUST have a value between 3 and 255.  If a client or server
      receives a TLV with an invalid TLV-Length, then the attribute
      which encapsulates that TLV MUST be deemed to be an "invalid
      attribute", it SHOULD be silently discarded.  If the encapsulating
      attribute is not discarded, it MUST NOT be handled in the same
      manner as a well-formed attribute.

      Note that an "invalid attribute" does not cause the entire packet
      to be discarded, or to be treated as a negative acknowledgement.
      Instead, only the "invalid attribute" is discarded.

   TLV-Value

      The Value field is one or more octets and contains information
      specific to the Attribute.  The format and length of the TLV-Value
      field is determined by the TLV-Type and TLV-Length fields.

      The TLV-Value field SHOULD encapsulate a previously defined RADIUS
      data type.  Using non-standard data types is NOT RECOMMENDED.  We
      note that the TLV-Value field MAY also contain one or more
      attributes of data type "tlv", which allows for simple grouping
      and multiple layers of nesting.

      The TLV-Value field is limited to containing 253 or fewer octets
      of data.  Specifications which require a TLV to contain more than
      253 octets of data are incompatible with RADIUS, and need to be
      redesigned.  Specifications which require the transport of empty
      Values (i.e. Length = 2) are incompatible with RADIUS, and need to
      be redesigned.

      The TLV-Value field MUST NOT contain data using the "Extended
      Type" formats defined in this document.  The base Extended
      Attributes format allows for sufficient flexibility that nesting
      them inside of a TLV offers little additional value.

   This TLV definition is compatible with the suggested format of the
   "String" field of the Vendor-Specific attribute, as defined in
   [RFC2865] Section 5.26, though that specification does not discuss



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   nesting.

   Vendors MAY use attributes of type "tlv" in any Vendor Specific
   Attribute.  We RECOMMEND using type "tlv" for VSAs, in preference to
   any other format.

2.3.1.  TLV Nesting

   TLVs may contain other TLVs.  When this occurs, the "container" TLV
   MUST be completely filled by the "contained" TLVs.  That is, the
   "container" TLV-Length field MUST be exactly two (2) more than the
   sum of the "contained" TLV-Length fields.  If the "contained" TLVs
   over-fill the "container" TLV, the "container" TLV MUST be considered
   to be an "invalid attribute", and handled as described above.

   The depth of TLV nesting is limited only by the restrictions on the
   TLV-Length field.  The limit of 253 octets of data results in a limit
   of 126 levels of nesting.  However, nesting depths of more than 4 are
   NOT RECOMMENDED.

2.4.  EVS Data Type

   We define a new data type in RADIUS, called "evs", for "Extended
   Vendor-Specific".  The "evs" data type is an encapsulation layer
   which which permits the "Value" field of an Attribute to contain a
   Vendor-Id, followed by a Vendor-Type, and then vendor-defined data.
   This data can in turn contain valid RADIUS data types, or any other
   data as determined by the vendor.

   This data type is intended use in attributes which carry Vendor-
   Specific information, as is done with the Vendor-Specific Attribute
   (26).  It is RECOMMENDED that this data type be used by a vendor only
   when the Vendor-Specific Attribute Type space has been fully
   allocated.

   Where [RFC2865] Section 5.26 makes a recommendation for the format of
   the data following the Vendor-Id, we give a strict definition.
   Experience has shown that many vendors have not followed the
   [RFC2865] recommendations, leading to interoperability issues.  We
   hope here to give vendors sufficient flexibility as to meet their
   needs, while minimizing the use of non-standard VSA formats.

   The "evs" data type MAY be used in Attributes having the format of
   "Extended Type" or "Extended Type with Flags".  It MUST NOT be used
   in any other Attribute definition, including standard RADIUS
   Attributes, TLVs, and VSAs.

   A summary of the "evs" data type format is shown below.  The fields



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   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Vendor-Id                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Vendor-Type   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  It SHOULD encapsulate a
      previously defined RADIUS data type.  Using non-standard data
      types is NOT RECOMMENDED.  We note that the String field may be of
      data type "tlv".  However, it MUST NOT be of data type "evs", as
      the use cases are unclear for one vendor delegating attribute type
      space to another vendor.

      The actual format of the information is site or application
      specific, and a robust implementation SHOULD support the field as
      undistinguished octets.  We recognise that Vendors have complete
      control over the contents and format of the String field, while at
      the same time recommending that good practices be followed.

      Further codification of the range of allowed usage of this field
      is outside the scope of this specification.

   Note that unlike the format described in [RFC2865] Section 5.26, this
   data type has no "Vendor length" field.  The length of the "String"
   field is implicit, and is determined by taking the "Length" of the
   encapsulating RADIUS Attribute, and subtracting the length of the
   attribute header including the 4 octets of Vendor-Id.  i.e. For
   "Extended Type" attributes, the length of the String field is seven
   (7) less than the value of the Length field.  For "Extended Type with
   Flags" attributes, the length of the String field is eight (8) less
   than the value of the Length field.



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2.5.  Integer64 Data Type

   We define a new data type in RADIUS, called "integer64", which
   carries a 64-bit unsigned integer in network byte order.

   This data type is intended to be used in any situation where there is
   a need to have counters which can count past 2^32.  The expected use
   og this data type is within Accounting-Request packets, but this data
   type SHOULD be used in any packet where 32-bit integers are expected
   to be insufficient.

   The "integer64" data type MAY be used in Attributes of any format,
   standard space, extended attributes, TLVs, and VSAs.

   A summary of the "integer64" data type 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                                                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Attributes having data type "integer64" MUST have the relevant Length
   field set to eight more than the length of the Attribute header.  For
   standard space Attributes and TLVs, this means that the Length field
   MUST be set to ten (10).  For "Extended Type" Attributes, the Length
   field MUST be set to eleven (11).  For "Extended Type with Flags"
   Attributes, the Length field MUST be set to twelve (12).


2.6.  Attribute Naming and Type Identifiers

   Attributes have traditionally been identified by a unique name and
   number.  For example, the attribute named "User-Name" has been
   allocated number one (1).  This scheme needs to be extended in order
   to be able to refer to attributes of Extended Type, and to TLVs.  It
   will also be used by IANA for allocating RADIUS Attribute Type
   values.

   The names and identifiers given here are intended to be used only in
   specifications.  The system presented here may not be useful when
   referring to the contents of a RADIUS packet.  It imposes no
   requirements on implementations, as implementations are free to
   reference RADIUS Attributes via any method they choose.




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2.6.1.  Attribute and TLV Naming

   RADIUS specifications traditionally use names consisting of one or
   more words, separated by hyphens, e.g.  "User-Name".  However, these
   names are not allocated from a registry, and there is no restriction
   other than convention on their global uniqueness.

   Similarly, vendors have often used their company name as the prefix
   for VSA names, though this practice is not universal.  For example,
   for a vendor named "Example", the name "Example-Attribute-Name"
   SHOULD be used instead of "Attribute-Name".  The second form can
   conflict with attributes from other vendors, whereas the first form
   cannot.

   We therefore RECOMMEND that specifications give names to Attributes
   which attempt to be globally unique across all RADIUS Attributes.  We
   RECOMMEND that vendors use their name as a unique prefix for
   attribute names.  We recognise that these suggestion may sometimes be
   difficult to implement in practice.

   TLVs SHOULD be named with a unique prefix that is shared among
   related attributes.  For example, a specification that defines a set
   of TLVs related to time could create attributes named "Time-Zone",
   "Time-Day", "Time-Hour", "Time-Minute", etc.

2.6.2.  Attribute Type Identifiers

   The RADIUS Attribute Type space defines a context for a particular
   "Extended-Type" field.  The "Extended-Type" field allows for 256
   possible type code values, with values 1 through 240 available for
   allocation.  We define here an identification method that uses a
   "dotted number" notation similar to that used for Object Identifiers
   (OIDs), formatted as "Type.Extended-Type".

   For example, and attribute within the Type space of 241, having
   Extended-Type of one (1), is uniquely identified as "241.1".
   Similarly, an attribute within the Type space of 246, having
   Extended-Type of ten (10), is uniquely identified as "246.10".

   The algorithm used to create the Attribute Identifier is simply to
   concatenate all of the various identification fields (e.g. Type,
   Extended-Type, etc.), starting from the encapsulating attribute, down
   to the final encapsulated TLV, separated by a '.' character.

2.6.3.  TLV Identifiers

   We can extend the Attribute reference scheme defined above for TLVs.
   This is done by leveraging the "dotted number" notation.  As above,



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   we define an additional TLV type space, within the "Extended Type"
   space, by appending another "dotted number" in order to identify the
   TLV.  This method can be replied in sequence for nested TLVs.

   For example, let us say that "245.1" identifies RADIUS Attribute Type
   245, containing an "Extended Type" of one (1), which is of type
   "tlv".  That attribute will contain 256 possible TLVs, one for each
   value of the TLV-Type field.  The first TLV-Type value of one (1) can
   then be identified by appending a ".1" to the number of the
   encapsulating attribute ("241.1"), to yield "241.1.1".  Similarly,
   the sequence "245.2.3.4" identifies RADIUS attribute 245, containing
   an "Extended Type" of two (2) which is of type "tlv", which in turn
   contains a TLV with TLV-Type number three (3), which in turn contains
   another TLV, wth TLV-Type number four (4).

2.6.4.  VSA Identifiers

   There has historically been no method for numerically addressing
   VSAs.  The "dotted number" method defined here can also be leveraged
   to create such an addressing scheme.  However, as the VSAs are
   completely under the control of each individual vendor, this section
   provides a suggested practice, but does not define a standard of any
   kind.

   The Vendor-Specific Attribute has been assigned the Attribute number
   26.  It in turn carries a 24-bit Vendor-Id, and possibly additional
   VSAs.  Where the VSAs follow the [RFC2865] Section 5.26 recommended
   format, a VSA can be identified as "26.Vendor-Id"."Vendor-Type".

   For example, Livingston has Vendor-Id 307, and has defined an
   attribute "IP-Pool" as number 6.  This VSA can be uniquely identified
   as 26.307.6.

   Note that there is no restriction on the size of the numerical values
   in this notation.  The Vendor-Id is a 24-bit number, and the VSA may
   have been assigned from a 16-bit vendor-specific Attribute type
   space.

   For example, the company USR has been allocated Vendor-Id 429, and
   has defined a "Version-Id" attribute as number 32768.  This VSA can
   be uniquely identified as 26.429.32768.

   Where a VSA is a TLV, the "dotted number" notation can be used as
   above: 26.VID.VSA.TLV1.TLV2.TLV3 where "TLVn" are the numerical
   values assigned by the vendor to the different nested TLVs.






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3.  Attribute Definitions

   We define four (4) attributes of "Extended Type", which are allocated
   from the "Reserved" Attribute Type codes of 241, 242, 243, and 244.
   We also define two (2) attributes of "Extended Type with Flags",
   which are allocated from the "Reserved" Attribute Type codes of 245
   and 246.

      Type  Name
      ----  ----
      241   Extended-Type-1
      242   Extended-Type-2
      243   Extended-Type-3
      244   Extended-Type-4
      245   Extended-Type-Flagged-1
      246   Extended-Type-Flagged-2

   The rest of this section gives a detailed definition for each
   Attribute based on the above summary.

3.1.  Extended-Type-1

   Description

      This attribute encapsulates attributes of the "Extended Type"
      format, in the RADIUS Attribute Type Space of 241.{1-255}.

   A summary of the Extended-Type-1 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     | Extended-Type |  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      241 for Extended-Type-1.

   Length

      >= 4

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA, in the 241.{1-255} RADIUS Attribute



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      Type Space.  Further definition of this field is given in Section
      2.1, above.

   String

      The String field is one or more octets.  Implementations not
      supporting this specification SHOULD support the field as
      undistinguished octets.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type" to determine the interpretation
      of the String field.


3.2.  Extended-Type-2

   Description

      This attribute encapsulates attributes of the "Extended Type"
      format, in the RADIUS Attribute Type Space of 242.{1-255}.

   A summary of the Extended-Type-2 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     | Extended-Type |  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      242 for Extended-Type-2.

   Length

      >= 4

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA, in the 242.{1-255} RADIUS Attribute
      Type Space.  Further definition of this field is given in Section
      2.1, above.

   String

      The String field is one or more octets.  Implementations not



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      supporting this specification SHOULD support the field as
      undistinguished octets.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type" to determine the interpretation
      of the String field


3.3.  Extended-Type-3

   Description

      This attribute encapsulates attributes of the "Extended Type"
      format, in the RADIUS Attribute Type Space of 243.{1-255}.

   A summary of the Extended-Type-3 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     | Extended-Type |  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      243 for Extended-Type-3.

   Length

      >= 4

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA, in the 243.{1-255} RADIUS Attribute
      Type Space.  Further definition of this field is given in Section
      2.1, above.

   String

      The String field is one or more octets.  Implementations not
      supporting this specification SHOULD support the field as
      undistinguished octets.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type" to determine the interpretation
      of the String field.



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3.4.  Extended-Type-4

   Description

      This attribute encapsulates attributes of the "Extended Type"
      format, in the RADIUS Attribute Type Space of 244.{1-255}.

   A summary of the Extended-Type-4 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     | Extended-Type |  Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      244 for Extended-Type-4.

   Length

      >= 4

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA, in the 244.{1-255} RADIUS Attribute
      Type Space.  Further definition of this field is given in Section
      2.1, above.

   String

      The String field is one or more octets.  Implementations not
      supporting this specification SHOULD support the field as
      undistinguished octets.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type" to determine the interpretation
      of the String Field.


3.5.  Extended-Type-Flagged-1

   Description

      This attribute encapsulates attributes of the "Extended Type with
      Flags" format, in the RADIUS Attribute Type Space of 245.{1-255}.



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   A summary of the Extended-Type-Flagged-1 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     | Extended-Type |M|   Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      245 for Extended-Type-Flagged-1

   Length

      >= 4

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA, in the 245.{1-255} RADIUS Attribute
      Type Space.  Further definition of this field is given in Section
      2.1, above.

   M (More)

      The More Flag is one (1) bit in length, and indicates whether or
      not the current attribute contains "more" than 251 octets of data.
      Further definition of this field is given in Section 2.2, above.

   Flags

      This field is 7 bits long, and is reserved for future use.
      Implementations MUST set it to zero (0) when encoding an attribute
      for sending in a packet.  The contents SHOULD be ignored on
      reception.

   String

      The String field is one or more octets.  Implementations not
      supporting this specification SHOULD support the field as
      undistinguished octets.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type" to determine the interpretation
      of the String field.



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3.6.  Extended-Type-Flagged-2

   Description

      This attribute encapsulates attributes of the "Extended Type with
      Flags" format, in the RADIUS Attribute Type Space of 246.{1-255}.

   A summary of the Extended-Type-Flagged-2 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     | Extended-Type |M|   Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Value ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      246 for Extended-Type-Flagged-2

   Length

      >= 4

   Extended-Type

      The Extended-Type field is one octet.  Up-to-date values of this
      field are specified by IANA, in the 246.{1-255} RADIUS Attribute
      Type Space.  Further definition of this field is given in Section
      2.1, above.

   M (More)

      The More Flag is one (1) bit in length, and indicates whether or
      not the current attribute contains "more" than 251 octets of data.
      Further definition of this field is given in Section 2.2, above.

   Flags

      This field is 7 bits long, and is reserved for future use.
      Implementations MUST set it to zero (0) when encoding an attribute
      for sending in a packet.  The contents SHOULD be ignored on
      reception.

   String




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      The String field is one or more octets.  Implementations not
      supporting this specification SHOULD support the field as
      undistinguished octets.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type" to determine the interpretation
      of the String field.

4.  Vendor Specific Attributes

   We define six new attributes which can carry Vendor Specific
   information.  We define four (4) attributes of the "Extended Type"
   format, with Type codes (241.26, 242.26, 243.26, 244.26), using the
   "evs" data type.  We also define two (2) attributes of "Extended Type
   with Flags" format, with Type codes (245.26, 246.26), using the "evs"
   data type.

      Type.Extended-Type  Name
      ------------------  ----
      241.26              Extended-Vendor-Specific-1
      242.26              Extended-Vendor-Specific-2
      243.26              Extended-Vendor-Specific-3
      244.26              Extended-Vendor-Specific-4
      245.26              Extended-Vendor-Specific-5
      246.26              Extended-Vendor-Specific-6

   The rest of this section gives a detailed definition for each
   Attribute based on the above summary.

4.1.  Extended-Vendor-Specific-1

   Description

      This attribute defines a RADIUS Type Code of 241.26, using the
      "evs" data type.

   A summary of the Extended-Vendor-Specific-1 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     | Extended-Type |  Vendor-Id ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Vendor-Id  (cont)                        |  Vendor-Type  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   Type.Extended-Type

      241.26 for Extended-Vendor-Specific-1

   Length

      >= 9

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  The actual format of the
      information is site or application specific, and a robust
      implementation SHOULD support the field as undistinguished octets.

      The codification of the range of allowed usage of this field is
      outside the scope of this specification.

      The length of the String field is eight (8) less then the value of
      the Length field.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type.Vendor-Id.Vendor-Type" to
      determine the interpretation of the String field.

4.2.  Extended-Vendor-Specific-2

   Description

      This attribute defines a RADIUS Type Code of 242.26, using the
      "evs" data type.

   A summary of the Extended-Vendor-Specific-2 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   |     Type      |    Length     | Extended-Type |  Vendor-Id ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Vendor-Id  (cont)                        |  Vendor-Type  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type.Extended-Type

      242.26 for Extended-Vendor-Specific-2

   Length

      >= 9

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  The actual format of the
      information is site or application specific, and a robust
      implementation SHOULD support the field as undistinguished octets.

      The codification of the range of allowed usage of this field is
      outside the scope of this specification.

      The length of the String field is eight (8) less then the value of
      the Length field.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type.Vendor-Id.Vendor-Type" to
      determine the interpretation of the String field.

4.3.  Extended-Vendor-Specific-3

   Description

      This attribute defines a RADIUS Type Code of 243.26, using the
      "evs" data type.



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   A summary of the Extended-Vendor-Specific-3 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     | Extended-Type |  Vendor-Id ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Vendor-Id  (cont)                        |  Vendor-Type  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type.Extended-Type

      243.26 for Extended-Vendor-Specific-3

   Length

      >= 9

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  The actual format of the
      information is site or application specific, and a robust
      implementation SHOULD support the field as undistinguished octets.

      The codification of the range of allowed usage of this field is
      outside the scope of this specification.

      The length of the String field is eight (8) less then the value of
      the Length field.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type.Vendor-Id.Vendor-Type" to
      determine the interpretation of the String field.




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4.4.  Extended-Vendor-Specific-4

   Description

      This attribute defines a RADIUS Type Code of 244.26, using the
      "evs" data type.

   A summary of the Extended-Vendor-Specific-3 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     | Extended-Type |  Vendor-Id ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ... Vendor-Id  (cont)                        |  Vendor-Type  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type.Extended-Type

      244.26 for Extended-Vendor-Specific-4

   Length

      >= 9

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  The actual format of the
      information is site or application specific, and a robust
      implementation SHOULD support the field as undistinguished octets.

      The codification of the range of allowed usage of this field is
      outside the scope of this specification.




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      The length of the String field is eight (8) less then the value of
      the Length field.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type.Vendor-Id.Vendor-Type" to
      determine the interpretation of the String field.

4.5.  Extended-Vendor-Specific-5

   Description

      This attribute defines a RADIUS Type Code of 245.26, using the
      "evs" data type.

   A summary of the Extended-Vendor-Specific-5 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     | Extended-Type |M|   Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Vendor-Id                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Vendor-Type   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type.Extended-Type

      245.26 for Extended-Vendor-Specific-5

   Length

      >= 10   (first fragment)
      >= 5    (subsequent fragments)

      When a VSA is fragmented across multiple Attributes, only the
      first Attribute contains the Vendor-Id and Vendor-Type fields.
      Subsequent Attributes contain fragments of the String field only.

   M (More)

      The More Flag is one (1) bit in length, and indicates whether or
      not the current attribute contains "more" than 251 octets of data.
      Further definition of this field is given in Section 2.2, above.

   Flags




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      This field is 7 bits long, and is reserved for future use.
      Implementations MUST set it to zero (0) when encoding an attribute
      for sending in a packet.  The contents SHOULD be ignored on
      reception.

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  The actual format of the
      information is site or application specific, and a robust
      implementation SHOULD support the field as undistinguished octets.

      The codification of the range of allowed usage of this field is
      outside the scope of this specification.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type.Vendor-Id.Vendor-Type" to
      determine the interpretation of the String field.

4.6.  Extended-Vendor-Specific-6

   Description

      This attribute defines a RADIUS Type Code of 246.26, using the
      "evs" data type.

   A summary of the Extended-Vendor-Specific-6 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     | Extended-Type |M|   Flags     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            Vendor-Id                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Vendor-Type   |  String ....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   Type.Extended-Type

      246.26 for Extended-Vendor-Specific-6

   Length

      >= 10   (first fragment)
      >= 5    (subsequent fragments)

      When a VSA is fragmented across multiple Attributes, only the
      first Attribute contains the Vendor-Id and Vendor-Type fields.
      Subsequent Attributes contain fragments of the String field only.

   M (More)

      The More Flag is one (1) bit in length, and indicates whether or
      not the current attribute contains "more" than 251 octets of data.
      Further definition of this field is given in Section 2.2, above.

   Flags

      This field is 7 bits long, and is reserved for future use.
      Implementations MUST set it to zero (0) when encoding an attribute
      for sending in a packet.  The contents SHOULD be ignored on
      reception.

   Vendor-Id

      The high-order octet is 0 and the low-order 3 octets are the SMI
      Network Management Private Enterprise Code of the Vendor in
      network byte order.

   Vendor-Type

      The Vendor-Type field is one octet.  Values are assigned at the
      sole discretion of the Vendor.

   String

      The String field is one or more octets.  The actual format of the
      information is site or application specific, and a robust
      implementation SHOULD support the field as undistinguished octets.

      The codification of the range of allowed usage of this field is
      outside the scope of this specification.

      Implementations supporting this specification MUST use the
      Identifier of "Type.Extended-Type.Vendor-Id.Vendor-Type" to



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      determine the interpretation of the String field.

5.  Compatibility with traditional RADIUS

   There are a number of potential compatibility issues with traditional
   RADIUS.  This section describes them.

5.1.  Attribute Allocation

   Some vendors have used Attribute Type codes from the "Reserved"
   space, as part of vendor-defined dictionaries.  This practice is
   considered anti-social behavior, as noted in [RFC6158].  These vendor
   definitions conflict with the attributes in the RADIUS Attribute Type
   space.  The conflicting definitions may make it difficult for
   implementations to support both those Vendor Attributes, and the new
   Extended Attribute formats.

   We RECOMMEND that RADIUS client and server implementations delete all
   references to these improperly defined attributes.  Failing that, we
   RECOMMEND that RADIUS server implementations have a per-client
   configurable flag which indicates which type of attributes are being
   sent from the client.  If the flag is set one way, the conflicting
   attributes can be interpreted as being improperly defined Vendor
   Specific Attributes. If the flag is set the other way, the attributes
   MUST be interpreted as being of the Extended Attributes format.  The
   default SHOULD be to interpret the attributes as being of the
   Extended Attributes format.

   Other methods of determining how to decode the attributes into a
   "correct" form are NOT RECOMMENDED.  Those methods are likely to be
   fragile and prone to error.

   We RECOMMEND that RADIUS server implementations re-use the above flag
   to determine which type of attributes to send in a reply message.  If
   the request is expected to contain the improperly defined attributes,
   the reply SHOULD NOT contain Extended Attributes.  If the request is
   expected to contain Extended Attributes, the reply MUST NOT contain
   the improper Attributes.

   RADIUS clients will have fewer issues than servers.  Clients MUST NOT
   send improperly defined Attributes in a request.  For replies,
   clients MUST interpret attributes as being of the Extended Attributes
   format, instead of the improper definitions.  These requirements
   impose no change in the RADIUS specifications, as such usage by
   vendors has always been in conflict with the standard requirements
   and the standards process.

   Existing clients that send these improperly defined attributes



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   usually have a configuration setting which can disable this behavior.
   We RECOMMEND that vendors ship products with the default set to
   "disabled".  We RECOMMEND that administrators set this flag to
   "disabled" on all equipment that they manage.

5.2.  Proxy Servers

   RADIUS Proxy servers will need to forward Attributes having the new
   format, even if they do not implement support for the encoding and
   decoding of those attributes.  We remind implementors of the
   following text in [RFC2865] Section 2.3:

      The forwarding server MUST NOT change the order of any attributes
      of the same type, including Proxy-State.

   This requirement solves some of the issues related to proxying of the
   new format, but not all.  The reason is that proxy servers are
   permitted to examine the contents of the packets that they forward.
   Many proxy implementations not only examine the attributes, but they
   refuse to forward attributes which they do not understand (i.e.
   attributes for which they have no local dictionary definitions).

   This practice is NOT RECOMMENDED.  Proxy servers SHOULD forward
   attributes, even ones which they do not understand, or which are not
   in a local dictionary.  When forwarded, these attributes SHOULD be
   sent verbatim, with no modifications or changes.  The only exception
   to this recommendation is when local site policy dictates that
   filtering of attributes has to occur.  For example, a filter at a
   visited network may require removal of certain authorization rules
   which apply to the home network, but not to the visited network.
   This filtering can sometimes be done even when the contents of the
   attributes are unknown, such as when all Vendor-Specific Attributes
   are designated for removal.

   As seen in [EDUROAM] many proxies do not follow these practices for
   unknown Attributes.  Some proxies filter out unknown attributes or
   attributes which have unexpected lengths (24%, 17/70), some truncate
   the attributes to the "expected" length (11%, 8/70), some discard the
   request entirely (1%, 1/70), with the rest (63%, 44/70) following the
   recommended practice of passing the attributes verbatim.  It will be
   difficult to widely use the Extended Attributes format until all non-
   conformant proxies are fixed.  We therefore RECOMMEND that all
   proxies which do not support the Extended Attributes (241 through
   246) define them as being of data type "string", and delete all other
   local definitions for those attributes.

   This last change should enable wider usage of the Extended Attributes
   format.



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6.  Guidelines

   This specification proposes a number of changes to RADIUS, and
   therefore requires a set of guidelines, as has been done in
   [RFC6158].


6.1.  Updates to RFC 6158

   This specification updates [RFC6158] by adding the data types "evs",
   "tlv" and "integer64"; defining them to be "basic" data types; and
   permitting their use subject to the restrictions outlined below.

   All other recommendations given in [RFC6158] are unchanged.  New
   recommendations for the use of the new data types and attribute
   formats are given below.

6.2.  Guidelines For the New Types

   We recommend the following guidelines when designing attributes using
   the new format.  The items listed below are not exhaustive.  As
   experience is gained with the new formats, later specifications may
   define additional guidelines.

   * The data type "evs" MUST NOT be used for standard RADIUS
     Attributes, or for TLVs, or for VSAs.

   * The data type "tlv" SHOULD NOT be used for standard RADIUS
     attributes.  While its use is NOT RECOMMENDED by [RFC6158], this
     specification updates [RFC6158] to permit the "tlv" data type in
     attributes using the Extended-Type format.

   * [RFC2866] "tagged" attributes MUST NOT be defined in the
     Extended-Type space.  The "tlv" data type should be used instead to
     group attributes.

   * The "integer64" data type MAY be used in any RADIUS attribute.
     The use of 64-bit integers is NOT RECOMMENDED by [RFC6158], but
     their utility is now evident.

   * For all other circumstances, the guidelines in [RFC6158] MUST
     be followed.


6.3.  Allocation Request Guidelines

   The following items give guidelines for allocation requests made in a
   RADIUS specification.



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   * Discretion is RECOMMENDED when requesting allocation of attributes.
     The new space is much larger than the old one, but it is not
     infinite.

   * When the Type spaces of 241.*, 242.*, 243.*, or 244.* are nearing
     exhaustion, a new specification SHOULD be written which requests
     allocation of one or more RADIUS Attributes from the "Reserved"
     space, using the "Extended Type" format.  This process is
     preferable to allocating "small" attributes from the 256.* and
     246.* Type spaces.

   * When the Type spaces of 245.* or 246.* are nearing exhaustion, a
     new specification SHOULD be written which requests allocation of
     one or more RADIUS Attributes from the "Reserved" space, using the
     "Extended Type with flags" format.

   * All other specifications SHOULD NOT request allocation from the
     standard Attribute Type Space (i.e. Attributes 1 through 255).
     That space is deprecated, and is not to be used.

   * Attributes which encode 252 octets or less of data SHOULD
     request allocation from the Type spaces of 241.*, 242.*, 243.*,
     or 244.*.

   * Attributes which encode 253 octets or more of data MUST request
     allocation from the Type spaces of 245.* or 246.*.

6.4.  TLV Guidelines

   The following items give guidelines for specifications using TLVs.

   * when multiple attributes are intended to be grouped or managed
     together, the use of TLVs to group related attributes is
     RECOMMENDED.

   * more than 4 layers (depth) of TLV nesting is NOT RECOMMENDED.

   * Interpretation of an attribute depends only on its type
     definition (e.g. Type.Extended-Type.TLV-Type, etc.), and
     not on its encoding or location in the RADIUS packet.

   * Where a group of TLVs is strictly defined, and not expected to
     change, and and totals less than 247 octets of data, they SHOULD
     request allocation from the Type spaces of 241.*, 242.*, 243.*, or
     244.*.

   * Where a group of TLVs is loosely defined, or is expected to change,
     they SHOULD request allocation from the Type spaces of 245.* or



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     246.*.

6.5.  Implementation Guidelines

   * RADIUS client implementations SHOULD support this specification
     as soon as possible.

   * RADIUS server implementations SHOULD support this specification
     as soon as possible.

   * RADIUS proxy servers SHOULD forward all attributes, even ones
     which they do not understand, or which are not in a local
     dictionary.  These attributes SHOULD be forwarded verbatim, with
     no modifications or changes.

   * Any attribute which is allocated from the Type spaces of 245.* or
     246.*, of data type "text", "string", or "tlv" can end up carrying
     more than 251 octets of data, up to the maximum RADIUS packet
     length (~4096 octets).  Specifications defining such attributes
     SHOULD define a maximum length.

6.6.  Vendor Guidelines

   * Vendors SHOULD use the existing Vendor-Specific Attribute Type
     space in preference to the new Extended-Vendor-Specific
     attributes, as this specification may take time to become widely
     deployed.

   * Vendors SHOULD implement this specification as soon as
     possible. The changes to RADIUS are relatively small, and are
     likely to quickly be used in new specifications.

7.  Rationale

   The path to extending the RADIUS protocol has been long and arduous.
   A number of proposals have been made and discarded by the RADEXT
   working group.  These proposals have been judged to be either too
   bulky, too complex, too simple, or to be unworkable in practice.  We
   do not otherwise explain here why earlier proposals did not obtain
   working group consensus.

   The changes outlined here have the benefit of being simple, as the
   "Extended Type" format requires only a one octet change to the
   Attribute format.  The downside is that the "Extended Type with
   Flags" format is awkward, and the 7 bits of Flags will likey never be
   used for anything.





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7.1.  Attribute Audit

   An audit of almost five thousand publicly available attributes
   [ATTR], shows the statistics summarized below. The attributes include
   over 100 Vendor dictionaries, along with the IANA assigned
   attributes:

      Count    Data Type
      -----    ---------
      2257     integer
      1762     text
      273      IPv4 Address
      225      string
      96       other data types
      35       IPv6 Address
      18       date
      10       integer64
      4        Interface Id
      3        IPv6 Prefix

      4683     Total

   The entries in the "Data Type" column are data types recommended by
   [RFC6158], along with "integer64".  The "other data types" row
   encompasses other data types.

   Manual inspection of the dictionaries shows that approximately 20 (or
   0.5%) attributes have the ability to transport more than 253 octets
   of data.  These attributes are divided between VSAs, and a small
   number of standard Attributes.  While the "Extended Type with Flags"
   format is therefore important, "long" attributes have had limited
   deployment

8.  Examples

   A few examples are presented here, in order to illustrate the
   encoding of the new attribute formats.  These examples are not
   intended to be exhaustive, as many others are possible.  For
   simplicity, we do not show complete packets, only attributes.

   The examples are given using a domain-specific language implemented
   by the program given in Appendix A.  The language is line oriented,
   and composed of a sequence of lines matching the grammar ([RFC5234])
   given below:

      Identifier = 1*DIGIT *( "." 1*DIGIT )

      HEXCHAR = HEXDIG HEXDIG



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      STRING = DQUOTE 1*CHAR DQUOTE

      TLV = "{" 1*DIGIT DATA "}"

      DATA = 1*HEXCHAR / 1*TLV / STRING

      LINE = Identifier DATA

   The progam has additional restrictions on its input that are not
   reflected in the above grammar.  For example, the portions of the
   Identifier which refer to Type and Extended-Type are limited to
   values between 1 and 255.  We trust that the source code in Appendix
   A is clear, and that these restrictions do not negatively affect the
   comprehensability of the examples.

   The program reads the input text, and interprets it as a set of
   instructions to create RADIUS Attributes.  It then prints the hex
   encoding of those attributes.  It implements the minimum set of
   functionality which achieves that goal.  This minimalism means that
   it does not use attribute dictionaries; it does not implement support
   for RADIUS data types; it can be used to encode attributes with
   invalid data field(s); and there is no requirement for consistency
   from one example to the next.  For example, it can be used to encode
   a User-Name attribute which contains non-UTF8 data, or a Framed-IP-
   Address which contains 253 octets of ASCII data.  As a result, it
   MUST NOT be used to create RADIUS Attributes for transport in a
   RADIUS message.

   However, the program correctly encodes the RADIUS attribute fields of
   "Type", "Length", "Extended-Type", "More", "Flags", "Vendor-Id",
   "Vendor-Type", and "Vendor-Length".  It can therefore be used to
   encode example attributes from input which is humanly readable.

   We do not give examples of "malformed" or "invalid attributes".  We
   also note that the examples show format, and not consistent meaning.
   A particular attribute type code may be used to demonstrate two
   different formats.  In real specifications, attributes have a static
   definitions based on their type code.

   The examples given below are strictly for demonstration purposes
   only, and do not provide a standard of any kind.

8.1.  Extended Type

   The following are a series of examples of the "Extended Type" format.

   Attribute encapsulating textual data.




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     241.1 "bob"
       -> f1 06 01 62 6f 62

   Attribute encapsulating a TLV with TLV-Type of one (1).

     241.2 { 1 23 45 }
       -> f1 07 02 01 04 23 45

   Attribute encapsulating two TLVs, one after the other.

     241.2 { 1 23 45 } { 2 67 89 }
       -> f1 0b 02 01 04 23 45 02 04 67 89

   Attribute encapsulating two TLVs, where the second TLV is itself
   encapsulating a TLV.

     241.2 { 1 23 45 } { 3 { 1 ab cd } }
       -> f1 0d 02 01 04 23 45 03 06 01 04 ab cd

   Attribute encapsulating two TLVs, where the second TLV is itself
   encapsulating two TLVs.

     241.2 { 1 23 45 } { 3 { 1 ab cd } { 2 "foo" } }
       -> f1 12 02 01 04 23 45 03 0b 01 04 ab cd 02 05 66 6f 6f

   Attribute encapsulating a TLV, which in turn encapsulates a TLV,
   to a depth of 5 nestings.

     241.1 { 1 { 2 { 3 { 4 { 5 cd ef } } } } }
       -> f1 0f 01 01 0c 02 0a 03 08 04 06 05 04 cd ef

   Attribute encapsulating an extended Vendor Specific attribute,
   with Vendor-Id of 1, and Vendor-Type of 4, which in turn
   encapsulates textual data.

     241.26.1.4 "test"
       -> f1 0c 1a 00 00 00 01 04 74 65 73 74

   Attribute encapsulating an extended Vendor Specific attribute, with
   Vendor-Id of 1, and Vendor-Type of 5, which in turn encapsulates
   a TLV with TLV-Type of 3, which encapsulates textual data.

     241.26.1.5 { 3 "test" }
       -> f1 0e 1a 00 00 00 01 05 03 06 74 65 73 74







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8.2.  Extended Type with Flags

   The following are a series of examples of the "Extended Type with
   flags" format.

      Attribute encapsulating textual data.

        245.1 "bob"
          -> f5 07 01 00 62 6f 62

      Attribute encapsulating a TLV with TLV-Type of one (1).

        245.2 { 1 23 45 }
          -> f5 08 02 00 01 04 23 45

      Attribute encapsulating two TLVs, one after the other.

        245.2 { 1 23 45 } { 2 67 89 }
          -> f5 0c 02 00 01 04 23 45 02 04 67 89

      Attribute encapsulating two TLVs, where the second TLV is itself
      encapsulating a TLV.

        245.2 { 1 23 45 } { 3 { 1 ab cd } }
          -> f5 0e 02 00 01 04 23 45 03 06 01 04 ab cd

      Attribute encapsulating two TLVs, where the second TLV is itself
      encapsulating two TLVs.

        245.2 { 1 23 45 } { 3 { 1 ab cd } { 2 "foo" } }
          -> f5 13 02 00 01 04 23 45 03 0b 01 04 ab cd 02 05 66 6f 6f

      Attribute encapsulating a TLV, which in turn encapsulates a TLV,
      to a depth of 5 nestings.

        245.1 { 1 { 2 { 3 { 4 { 5 cd ef } } } } }
          -> f5 10 01 00 01 0c 02 0a 03 08 04 06 05 04 cd ef

      Attribute encapsulating an extended Vendor Specific attribute,
      with Vendor-Id of 1, and Vendor-Type of 4, which in turn
      encapsulates textual data.

        245.26.1.4 "test"
          -> f5 0d 1a 00 00 00 00 01 04 74 65 73 74

      Attribute encapsulating an extended Vendor Specific attribute,
      with Vendor-Id of 1, and Vendor-Type of 5, which in turn
      encapsulates a TLV with TLV-Type of 3, which encapsulates



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      textual data.

        245.26.1.5 { 3 "test" }
          -> f5 0f 1a 00 00 00 00 01 05 03 06 74 65 73 74

      Attribute encapsulating more than 251 octets of data.  The "Data"
      portions are indented for readability.

        245.4 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbcccccccccccccccccccc
              cccccccccc
          -> f5 ff 04 80 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa ab bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb f5 13 04 00 cc
             cc cc cc cc cc cc cc cc cc cc cc cc cc cc

      Attribute encapsulating an extended Vendor Specific attribute,
      with Vendor-Id of 1, and Vendor-Type of 6, which in turn
      encapsulates more than 251 octets of data.

      As the VSA encapsulates more than 251 octets of data, it is
      split into two RADIUS attributes.  The first attribute has the
      More flag set, and carries the Vendor-Id and Vendor-Type.
      The second attribute has the More flag clear, and carries
      the rest of the data portion of the VSA.  Note that the second
      attribute does not include the Vendor-Id ad Vendor-Type fields.

      The "Data" portions are indented for readability.

        245.26.1.6 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa



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              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
              aaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
              bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbccccccccccccc
              ccccccccccccccccc
          -> f5 ff 1a 80 00 00 00 01 06 aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
             aa aa aa aa aa aa aa aa aa aa aa aa aa aa ab bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
             bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb f5 17 1a 00 bb
             bb bb bb bb cc cc cc cc cc cc cc cc cc cc 13 45 67 89


9.  IANA Considerations

   This document has multiple impacts on IANA, in the "RADIUS Attribute
   Types" registry.  Attribute types which were previously reserved are
   now allocated, previously free attributes are marked deprecated, and
   the registry is extended from a simple 8-bit array to a tree-like
   structure, up to a maximum depth of 125 nodes.


9.1.  Attribute Allocations

   IANA is requested to move the "Unassigned" numbers in the range
   144-191 from "Unassigned" to "Deprecated".  New allocations are
   normally taken from the Extended Type space, starting with lower
   numbered attributes.  However, allocation from the "Deprecated" space
   can still be performed by publication of an IETF specification, where
   that specification requests allocation from the "Deprecated" space,
   and gives reasons why use of the Extended Type space is impossible.

   IANA is requested to move the following numbers from "Reserved", to
   allocated, with the following names:

   * 241 Extended-Type-1
   * 242 Extended-Type-2



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   * 243 Extended-Type-3
   * 244 Extended-Type-4
   * 245 Extended-Type-Flagged-1
   * 246 Extended-Type-Flagged-2

   These attributes serve as an encapsulation layer for the new RADIUS
   Attribute Type tree.

9.2.  RADIUS Attribute Type Tree

   Each of the attributes allocated above extends the "RADIUS Attribute
   Types" to an N-ary tree, via a "dotted number" notation.  Each number
   in the tree is an 8-bit value (1 to 255).  The value zero (0) is not
   used.  Currently, only one level of the tree is defined:

   * 241           Extended-Attribute-1
   * 241.{1-25}    Unassigned
   * 241.26        Extended-Vendor-Specific-1
   * 241.{27-240}  Unassigned
   * 241.{241-255} Reserved
   * 242           Extended-Attribute-2
   * 242.{1-25}    Unassigned
   * 242.26        Extended-Vendor-Specific-2
   * 242.{27-240}  Unassigned
   * 243           Extended-Attribute-3
   * 242.{241-255} Reserved
   * 243.{1-25}    Unassigned
   * 243.26        Extended-Vendor-Specific-3
   * 243.{27-240}  Unassigned
   * 243.{241-255} Reserved
   * 244           Extended-Attribute-4
   * 244.{1-25}    Unassigned
   * 244.26        Extended-Vendor-Specific-4
   * 244.{27-240}  Unassigned
   * 244.{241-255} Reserved
   * 245           Extended-Attribute-5
   * 245.{1-25}    Unassigned
   * 245.26        Extended-Vendor-Specific-5
   * 245.{27-240}  Unassigned
   * 245.{241-255} Reserved
   * 246           Extended-Attribute-6
   * 246.{1-25}    Unassigned
   * 245.26        Extended-Vendor-Specific-6
   * 246.{27-240}  Unassigned
   * 246.{241-255} Reserved

   The values marked "Unassigned" above are available for assignment by
   IANA in future RADIUS specifications.  The values marked "Reserved"



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   are reserved for future use.

9.3.  Extending the Attribute Type Tree

   When specifications request allocation of an attribute of data type
   "tlv", that allocation extends the Attribute Type Tree by one more
   level.  The value zero (0) is not used.  Values 254 and 255 are
   Reserved.  All other values are available for allocation.

   For example, if a new attribute "Example-TLV" of data type "tlv" is
   assigned the identifier "245.1", then the extended tree will be
   allocation as below:

   * 245.1           Example-TLV
   * 245.1.{1-253}   Unassigned
   * 245.1.{254-255} Reserved

   Note that this example does not define an "Example-TLV" attribute.

   The Attribute Type Tree can be extended multiple levels in one
   specification when the specification requests allocation of nested
   TLVs.

10.  Security Considerations

   This document defines new formats for data carried inside of RADIUS,
   but otherwise makes no changes to the security of the RADIUS
   protocol.

   Attacks on cryptographic hashes are well known, and are getting
   better with time, as discussed in[RFC4270].  RADIUS uses the MD5 hash
   [RFC1321] for packet authentication and attribute obfuscation.  There
   are ongoing efforts in the IETF to analyze and address these issues
   for the RADIUS protocol.

   As with any protocol change, code changes are required in order to
   implement the new features.  These code changes have the potential to
   introduce new vulnerabilities in the software.  Since the RADIUS
   server performs network authentication, it is an inviting target for
   attackers.  We RECOMMEND that access to RADIUS servers be kept to a
   minimum.

11.  References

11.1.  Normative references

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



DeKok, Alan                   Informational                    [Page 44]

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[RFC2865] Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
          Authentication Dial In User Service (RADIUS)", RFC 2865, June
          2000.

11.2.  Informative references

[RFC1321] Rivest, R. "The MD5 Message-Digest Algorithm", RFC 1321,
          April, 1992

[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.

[RFC2868] Zorn, G., et al, " RADIUS Attributes for Tunnel Protocol
          Support", RFC 2868, June 2000.

[RFC4270] Hoffman, P, and Schneier, B, "Attacks on Cryptographic Hashes
          in Internet Protocols", RFC 4270, November 2005.

[RFC5234] Crocker, D. (Ed.), and Overell, P., "Augmented BNF for Syntax
          Specifications: ABNF", RFC 5234, October 2005.

[RFC6158] DeKok, A., and Weber, G., "RADIUS Design Guidelines", RFC
          6158, March 2011.

[EDUROAM] Internal Eduroam testing page, data retrieved 04 August 2010.

[ATTR]    http://github.com/alandekok/freeradius-
          server/tree/master/share/, data retrieved September 2010.

Acknowledgments

   This document is the result of long discussions in the IETF RADEXT
   working group.  The authors would like to thank all of the
   participants who contributed various ideas over the years.  Their
   feedback has been invaluable, and has helped to make this
   specification better.
















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Appendix A - Extended Attribute Generator Program

   This section contains "C" program source which can be used for
   testing.  It reads a line-oriented text file, parses it to create
   RADIUS formatted attributes, and prints the hex version of those
   attributes to standard output.

   The input accepts a grammar similar to that given in Section 8, with
   some modifications for usability.  For example, blank lines are
   allowed, lines beginning with a '#' character are interpreted as
   comments, numbers (RADIUS Types, etc.) are checked for minimum /
   maximum values, and RADIUS Attribute lengths are enforced.

   The program is included here for demonstration purposes only, and
   does not define a standard of any kind.

   ------------------------------------------------------------
   /*
    * Copyright (c) 2010 IETF Trust and the persons identified as
    * authors of the code.  All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
    * are met:
    *
    * Redistributions of source code must retain the above copyright
    * notice, this list of conditions and the following disclaimer.
    *
    * Redistributions in binary form must reproduce the above copyright
    * notice, this list of conditions and the following disclaimer in
    * the documentation and/or other materials provided with the
    * distribution.
    *
    * Neither the name of Internet Society, IETF or IETF Trust, nor the
    * names of specific contributors, may be used to endorse or promote
    * products derived from this software without specific prior written
    * permission.
    *
    * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
    * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
    * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
    * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
    * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
    * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
    * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
    * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,



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    * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
    * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    * SUCH DAMAGE.
    *
    *  Author:  Alan DeKok <aland@networkradius.com>
    */
   #include <stdlib.h>
   #include <stdio.h>
   #include <stdint.h>
   #include <string.h>
   #include <errno.h>
   #include <ctype.h>

   static int encode_tlv(char *buffer, uint8_t *output, size_t outlen);

   static const char *hextab = "0123456789abcdef";

   static int encode_data_string(char *buffer,
                        uint8_t *output, size_t outlen)
   {
        int length = 0;
        char *p;

        p = buffer + 1;

        while (*p && (outlen > 0)) {
             if (*p == '"') {
                  return length;
             }

             if (*p != '\\') {
                  *(output++) = *(p++);
                  outlen--;
                  length++;
                  continue;
             }

             switch (p[1]) {
             default:
                  *(output++) = p[1];
                  break;

             case 'n':
                  *(output++) = '\n';
                  break;

             case 'r':
                  *(output++) = '\r';



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                  break;

             case 't':
                  *(output++) = '\t';
                  break;
             }

             outlen--;
             length++;
        }

        fprintf(stderr, "String is not terminated\n");
        return 0;
   }

   static int encode_data_tlv(char *buffer, char **endptr,
                     uint8_t *output, size_t outlen)
   {
        int depth = 0;
        int length;
        char *p;

        for (p = buffer; *p != '\0'; p++) {
             if (*p == '{') depth++;
             if (*p == '}') {
                  depth--;
                  if (depth == 0) break;
             }
        }

        if (*p != '}') {
             fprintf(stderr, "No trailing '}' in string starting "
                  "with \"%s\"\n",
                  buffer);
             return 0;
        }

        *endptr = p + 1;
        *p = '\0';

        p = buffer + 1;
        while (isspace((int) *p)) p++;

        length = encode_tlv(p, output, outlen);
        if (length == 0) return 0;

        return length;
   }



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   static int encode_data(char *p, uint8_t *output, size_t outlen)
   {
        int length;

        if (!isspace((int) *p)) {
             fprintf(stderr, "Invalid character following attribute "
                  "definition\n");
             return 0;
        }

        while (isspace((int) *p)) p++;

        if (*p == '{') {
             int sublen;
             char *q;

             length = 0;

             do {
                  while (isspace((int) *p)) p++;
                  if (!*p) {
                       if (length == 0) {
                            fprintf(stderr, "No data\n");
                            return 0;
                       }

                       break;
                  }

                  sublen = encode_data_tlv(p, &q, output, outlen);
                  if (sublen == 0) return 0;

                  length += sublen;
                  output += sublen;
                  outlen -= sublen;
                  p = q;
             } while (*q);

             return length;
        }

        if (*p == '"') {
             length = encode_data_string(p, output, outlen);
             return length;
        }

        length = 0;
        while (*p) {



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             char *c1, *c2;

             while (isspace((int) *p)) p++;

             if (!*p) break;

             if(!(c1 = memchr(hextab, tolower((int) p[0]), 16)) ||
                !(c2 = memchr(hextab, tolower((int)  p[1]), 16))) {
                  fprintf(stderr, "Invalid data starting at "
                       "\"%s\"\n", p);
                  return 0;
             }

             *output = ((c1 - hextab) << 4) + (c2 - hextab);
             output++;
             length++;
             p += 2;

             outlen--;
             if (outlen == 0) {
                  fprintf(stderr, "Too much data\n");
                  return 0;
             }
        }

        if (length == 0) {
             fprintf(stderr, "Empty string\n");
             return 0;
        }

        return length;
   }

   static int decode_attr(char *buffer, char **endptr)
   {
        long attr;

        attr = strtol(buffer, endptr, 10);
        if (*endptr == buffer) {
             fprintf(stderr, "No valid number found in string "
                  "starting with \"%s\"\n", buffer);
             return 0;
        }

        if (!**endptr) {
             fprintf(stderr, "Nothing follows attribute number\n");
             return 0;
        }



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        if ((attr <= 0) || (attr > 256)) {
             fprintf(stderr, "Attribute number is out of valid "
                  "range\n");
             return 0;
        }

        return (int) attr;
   }

   static int decode_vendor(char *buffer, char **endptr)
   {
        long vendor;

        if (*buffer != '.') {
             fprintf(stderr, "Invalid separator before vendor id\n");
             return 0;
        }

        vendor = strtol(buffer + 1, endptr, 10);
        if (*endptr == (buffer + 1)) {
             fprintf(stderr, "No valid vendor number found\n");
             return 0;
        }

        if (!**endptr) {
             fprintf(stderr, "Nothing follows vendor number\n");
             return 0;
        }

        if ((vendor <= 0) || (vendor > (1 << 24))) {
             fprintf(stderr, "Vendor number is out of valid range\n");
             return 0;
        }

        if (**endptr != '.') {
             fprintf(stderr, "Invalid data following vendor number\n");
             return 0;
        }
        (*endptr)++;

        return (int) vendor;
   }

   static int encode_tlv(char *buffer, uint8_t *output, size_t outlen)
   {
        int attr;
        int length;
        char *p;



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        attr = decode_attr(buffer, &p);
        if (attr == 0) return 0;

        output[0] = attr;
        output[1] = 2;

        if (*p == '.') {
             p++;
             length = encode_tlv(p, output + 2, outlen - 2);

        } else {
             length = encode_data(p, output + 2, outlen - 2);
        }

        if (length == 0) return 0;
        if (length > (255 - 2)) {
             fprintf(stderr, "TLV data is too long\n");
             return 0;
        }

        output[1] += length;

        return length + 2;
   }

   static int encode_vsa(char *buffer, uint8_t *output, size_t outlen)
   {
        int vendor;
        int attr;
        int length;
        char *p;

        vendor = decode_vendor(buffer, &p);
        if (vendor == 0) return 0;

        output[0] = 0;
        output[1] = (vendor >> 16) & 0xff;
        output[2] = (vendor >> 8) & 0xff;
        output[3] = vendor & 0xff;

        length = encode_tlv(p, output + 4, outlen - 4);
        if (length == 0) return 0;
        if (length > (255 - 6)) {
             fprintf(stderr, "VSA data is too long\n");
             return 0;
        }





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        return length + 4;
   }

   static int encode_evs(char *buffer, uint8_t *output, size_t outlen)
   {
        int vendor;
        int attr;
        int length;
        char *p;

        vendor = decode_vendor(buffer, &p);
        if (vendor == 0) return 0;

        attr = decode_attr(p, &p);
        if (attr == 0) return 0;

        output[0] = 0;
        output[1] = (vendor >> 16) & 0xff;
        output[2] = (vendor >> 8) & 0xff;
        output[3] = vendor & 0xff;
        output[4] = attr;

        length = encode_data(p, output + 5, outlen - 5);
        if (length == 0) return 0;

        return length + 5;
   }

   static int encode_extended(char *buffer,
                     uint8_t *output, size_t outlen)
   {
        int attr;
        int length;
        char *p;

        attr = decode_attr(buffer, &p);
        if (attr == 0) return 0;

        output[0] = attr;

        if (attr == 26) {
             length = encode_evs(p, output + 1, outlen - 1);
        } else {
             length = encode_data(p, output + 1, outlen - 1);
        }
        if (length == 0) return 0;
        if (length > (255 - 3)) {
             fprintf(stderr, "Extended Attr data is too long\n");



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             return 0;
        }

        return length + 1;
   }

   static int encode_extended_flags(char *buffer,
                        uint8_t *output, size_t outlen)
   {
        int attr;
        int length, total;
        char *p;

        attr = decode_attr(buffer, &p);
        if (attr == 0) return 0;

        /* output[0] is the extended attribute */
        output[1] = 4;
        output[2] = attr;
        output[3] = 0;

        if (attr == 26) {
             length = encode_evs(p, output + 4, outlen - 4);
             if (length == 0) return 0;

             output[1] += 5;
             length -= 5;
        } else {
             length = encode_data(p, output + 4, outlen - 4);
        }
        if (length == 0) return 0;

        total = 0;
        while (1) {
             int sublen = 255 - output[1];

             if (length <= sublen) {
                  output[1] += length;
                  total += output[1];
                  break;
             }

             length -= sublen;

             memmove(output + 255 + 4, output + 255, length);
             memcpy(output + 255, output, 4);

             output[1] = 255;



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             output[3] |= 0x80;

             output += 255;
             output[1] = 4;
             total += 255;
        }

        return total;
   }

   static int encode_rfc(char *buffer, uint8_t *output, size_t outlen)
   {
        int attr;
        int length, sublen;
        char *p;

        attr = decode_attr(buffer, &p);
        if (attr == 0) return 0;

        length = 2;
        output[0] = attr;
        output[1] = 2;

        if (attr == 26) {
             sublen = encode_vsa(p, output + 2, outlen - 2);

        } else if ((*p == ' ') || ((attr < 241) || (attr > 246))) {
             sublen = encode_data(p, output + 2, outlen - 2);

        } else {
             if (*p != '.') {
                  fprintf(stderr, "Invalid data following "
                       "attribute number\n");
                  return 0;
             }

             if (attr < 245) {
                  sublen = encode_extended(p + 1,
                                  output + 2, outlen - 2);
             } else {

                  /*
                   *   Not like the others!
                   */
                  return encode_extended_flags(p + 1, output, outlen);
             }
        }
        if (sublen == 0) return 0;



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        if (sublen > (255 -2)) {
             fprintf(stderr, "RFC Data is too long\n");
             return 0;
        }

        output[1] += sublen;
        return length + sublen;
   }

   int main(int argc, char *argv[])
   {
        int lineno;
        size_t i, outlen;
        FILE *fp;
        char input[8192], buffer[8192];
        uint8_t output[4096];

        if ((argc < 2) || (strcmp(argv[1], "-") == 0)) {
             fp = stdin;
        } else {
             fp = fopen(argv[1], "r");
             if (!fp) {
                  fprintf(stderr, "Error opening %s: %s\n",
                       argv[1], strerror(errno));
                  exit(1);
             }
        }

        lineno = 0;
        while (fgets(buffer, sizeof(buffer), fp) != NULL) {
             char *p = strchr(buffer, '\n');

             lineno++;

             if (!p) {
                  if (!feof(fp)) {
                       fprintf(stderr, "Line %d too long in %s\n",
                            lineno, argv[1]);
                       exit(1);
                  }
             } else {
                  *p = '\0';
             }

             p = strchr(buffer, '#');
             if (p) *p = '\0';

             p = buffer;



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             while (isspace((int) *p)) p++;
             if (!*p) continue;

             strcpy(input, p);
             outlen = encode_rfc(input, output, sizeof(output));
             if (outlen == 0) {
                  fprintf(stderr, "Parse error in line %d of %s\n",
                       lineno, input);
                  exit(1);
             }

             printf("%s -> ", buffer);
             for (i = 0; i < outlen; i++) {
                  printf("%02x ", output[i]);
             }
             printf("\n");
        }

        if (fp != stdin) fclose(fp);

        return 0;
   }
   ------------------------------------------------------------


Author's Address

   Alan DeKok
   Network RADIUS SARL
   15 av du Granier
   38240 Meylan
   France

   Email: aland@networkradius.com
   URI: http://networkradius.com

   Avi Lior
   Bridgewater Systems Corporation
   303 Terry Fox Drive
   Suite 100
   Ottawa, Ontario  K2K 3J1
   Canada

   Phone: +1 (613) 591-6655
   Email: avi@bridgewatersystems.com
   URI:   http://www.bridgewatersystems.com/





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