💾 Archived View for gemini.bortzmeyer.org › rfc-mirror › rfc6929.txt captured on 2024-06-16 at 15:53:47.
⬅️ Previous capture (2021-11-30)
-=-=-=-=-=-=-
Internet Engineering Task Force (IETF) A. DeKok
Request for Comments: 6929 Network RADIUS
Updates: 2865, 3575, 6158 A. Lior
Category: Standards Track April 2013
ISSN: 2070-1721
Remote Authentication Dial-In User Service (RADIUS)
Protocol Extensions
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 that can carry more than 253 octets of data. This
document defines changes to RADIUS that address all of the above
problems.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6929.
Copyright Notice
Copyright (c) 2013 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.
DeKok & Lior Standards Track [Page 1]
RFC 6929 RADIUS Extensions April 2013
Table of Contents
1. Introduction ....................................................3
1.1. Caveats and Limitations ....................................5
1.1.1. Failure to Meet Certain Goals .......................5
1.1.2. Implementation Recommendations ......................5
1.2. Terminology ................................................6
1.3. Requirements Language ......................................7
2. Extensions to RADIUS ............................................7
2.1. Extended Type ..............................................8
2.2. Long Extended Type .........................................9
2.3. TLV Data Type .............................................12
2.3.1. TLV Nesting ........................................14
2.4. EVS Data Type .............................................14
2.5. Integer64 Data Type .......................................16
2.6. Vendor-Id Field ...........................................16
2.7. Attribute Naming and Type Identifiers .....................17
2.7.1. Attribute and TLV Naming ...........................17
2.7.2. Attribute Type Identifiers .........................18
2.7.3. TLV Identifiers ....................................18
2.7.4. VSA Identifiers ....................................18
2.8. Invalid Attributes ........................................19
3. Attribute Definitions ..........................................21
3.1. Extended-Type-1 ...........................................21
3.2. Extended-Type-2 ...........................................22
3.3. Extended-Type-3 ...........................................23
3.4. Extended-Type-4 ...........................................24
3.5. Long-Extended-Type-1 ......................................25
3.6. Long-Extended-Type-2 ......................................26
4. Vendor-Specific Attributes .....................................27
4.1. Extended-Vendor-Specific-1 ................................28
4.2. Extended-Vendor-Specific-2 ................................29
4.3. Extended-Vendor-Specific-3 ................................30
4.4. Extended-Vendor-Specific-4 ................................31
4.5. Extended-Vendor-Specific-5 ................................32
4.6. Extended-Vendor-Specific-6 ................................34
5. Compatibility with Traditional RADIUS ..........................35
5.1. Attribute Allocation ......................................35
5.2. Proxy Servers .............................................36
DeKok & Lior Standards Track [Page 2]
RFC 6929 RADIUS Extensions April 2013
6. Guidelines .....................................................37
6.1. Updates to RFC 6158 .......................................37
6.2. Guidelines for Simple Data Types ..........................38
6.3. Guidelines for Complex Data Types .........................38
6.4. Design Guidelines for the New Types .......................39
6.5. TLV Guidelines ............................................40
6.6. Allocation Request Guidelines .............................40
6.7. Allocation Request Guidelines for TLVs ....................41
6.8. Implementation Guidelines .................................42
6.9. Vendor Guidelines .........................................42
7. Rationale for This Design ......................................42
7.1. Attribute Audit ...........................................43
8. Diameter Considerations ........................................44
9. Examples .......................................................44
9.1. Extended Type .............................................46
9.2. Long Extended Type ........................................47
10. IANA Considerations ...........................................50
10.1. Attribute Allocations ....................................50
10.2. RADIUS Attribute Type Tree ...............................50
10.3. Allocation Instructions ..................................52
10.3.1. Requested Allocation from the Standard Space ......52
10.3.2. Requested Allocation from the Short
Extended Space ....................................52
10.3.3. Requested Allocation from the Long
Extended Space ....................................52
10.3.4. Allocation Preferences ............................52
10.3.5. Extending the Type Space via the TLV Data Type ....53
10.3.6. Allocation within a TLV ...........................53
10.3.7. Allocation of Other Data Types ....................54
11. Security Considerations .......................................54
12. References ....................................................54
12.1. Normative References .....................................54
12.2. Informative References ...................................55
13. Acknowledgments ...............................................55
Appendix A. Extended Attribute Generator Program ..................56
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 impractical, and a more powerful mechanism is needed.
Multiple Attributes have been defined that 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
DeKok & Lior Standards Track [Page 3]
RFC 6929 RADIUS Extensions April 2013
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 changes
given in this document:
* 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 (Section 2.1).
* Allocating 4 attributes as using the format of "Extended Type".
This allocation extends the RADIUS Attribute Type space by
approximately 1000 values (Sections 3.1, 3.2, 3.3, and 3.4).
* Defining a "Long Extended Type" format, which inserts an additional
octet between the "Extended Type" octet and the "Value" field.
This method gives us a general way of adding more functionality to
the protocol (Section 2.2).
* Defining a method that uses the additional octet in the "Long
Extended Type" to indicate data fragmentation across multiple
Attributes. This method provides a standard way for an Attribute
to carry more than 253 octets of data (Section 2.2).
* Allocating 2 attributes as using the format "Long Extended Type".
This allocation extends the RADIUS Attribute Type space by an
additional 500 values (Sections 3.5 and 3.6).
* Defining a new "Type-Length-Value" (TLV) data type. This 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 (Section 2.3).
* Defining a new "Extended-Vendor-Specific" (EVS) data type. This
data type allows an attribute to carry Vendor-Specific Attributes
(VSAs) inside of the new Attribute formats (Section 2.4).
* Defining a new "integer64" data type. This data type allows
counters that track more than 2^32 octets of data (Section 2.5).
* Allocating 6 attributes using the new EVS data type. This
allocation extends the Vendor-Specific Attribute Type space by over
1500 values (Sections 4.1 through 4.6).
DeKok & Lior Standards Track [Page 4]
RFC 6929 RADIUS Extensions April 2013
* Defining the "Vendor-Id" for Vendor-Specific Attributes to
encompass the entire 4 octets of the Vendor field. [RFC2865]
Section 5.26 defined it to be 3 octets, with the fourth octet being
zero (Section 2.6).
* Describing compatibility with existing RADIUS systems (Section 5).
* Defining guidelines for the use of these changes for IANA,
implementations of this specification, and for future RADIUS
specifications (Section 6).
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 difficulty of implementation.
1.1. Caveats and Limitations
This section describes some caveats and limitations of the proposal.
1.1.1. Failure to Meet Certain Goals
One goal that was not met by the above modifications is to have an
incentive for standards to use the new space. That incentive is
being provided by the exhaustion of the standard space.
1.1.2. Implementation Recommendations
It is RECOMMENDED that implementations support this specification.
It is RECOMMENDED that new specifications use the formats defined in
this specification.
The alternative to the above recommendations is a circular argument
of not implementing this specification because no other standards
reference it, and also not defining new standards referencing this
specification because no implementations exist.
As noted earlier, the standard space is almost entirely allocated.
Ignoring the looming crisis benefits no one.
DeKok & Lior Standards Track [Page 5]
RFC 6929 RADIUS Extensions April 2013
1.2. 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) but the contents of the
Attribute do not follow the correct format, for example, an
Attribute of type "address" that encapsulates more than four, or
less than four, octets of data. See Section 2.8 for a more
complete definition.
Standard space
This refers to codes in the RADIUS Attribute Type space that are
allocated by IANA and that follow the format defined in Section 5
of [RFC2865].
Extended space
This refers to codes in the RADIUS Attribute Type space that
require the extensions defined in this document and are an
extension of the standard space, but that cannot be represented
within the standard space.
Short extended space
This refers to codes in the extended space that use the "Extended
Type" format.
Long extended space
This refers to codes in the extended space that use the "Long
Extended Type" format.
The following terms are used here with the meanings defined in BCP 26
[RFC5226]: "namespace", "assigned value", "registration", "Private
Use", "Reserved", "Unassigned", "IETF Review", and "Standards
Action".
DeKok & Lior Standards Track [Page 6]
RFC 6929 RADIUS Extensions April 2013
1.3. 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].
2. Extensions to RADIUS
This section defines two new Attribute formats: "Extended Type" and
"Long Extended Type". It defines a new Type-Length-Value (TLV) data
type, an Extended-Vendor-Specific (EVS) data type, and an Integer64
data type. It defines a new method for naming attributes and
identifying Attributes using the new Attribute formats. It finally
defines the new term "invalid attribute" and describes how it affects
implementations.
The new Attribute formats are designed to be compatible with the
Attribute format given in [RFC2865] Section 5. The meaning and
interpretation of the Type and Length fields are unchanged from that
specification. This reuse allows the new formats to be compatible
with RADIUS implementations that do not implement this specification.
Those implementations can simply ignore the "Value" field of an
attribute or forward it verbatim.
The changes to the Attribute format come about by "stealing" one or
more octets from the "Value" field. This change has the effect that
the "Value" field of [RFC2865] Section 5 contains both the new octets
given here and any attribute-specific Value. The result is that
"Value"s in this specification are limited to less than 253 octets in
size. This limitation is overcome through the use of the "Long
Extended Type" format.
We reiterate that the formats given in this document do not insert
new data into an attribute. Instead, we "steal" one octet of Value,
so that the definition of the Length field remains unchanged. The
new Attribute formats are designed to be compatible with the
Attribute format given in [RFC2865] Section 5. The meaning and
interpretation of the Type and Length fields is unchanged from that
specification. This reuse allows the new formats to be compatible
with RADIUS implementations that do not implement this specification.
Those implementations can simply ignore the "Value" field of an
attribute or forward it verbatim.
DeKok & Lior Standards Track [Page 7]
RFC 6929 RADIUS Extensions April 2013
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
The Length field is one octet and indicates the length of this
Attribute, including the Type, Length, "Extended-Type", and
"Value" fields. 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 considered to be an "invalid
attribute" and handled as per Section 2.8, below.
Extended-Type
The Extended-Type field is one octet. Up-to-date values of this
field are specified according to the policies and rules described
in Section 10. 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 MUST
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 3.5, below, for additional discussion.
A RADIUS server MAY ignore Attributes with an unknown
"Type.Extended-Type".
A RADIUS client MAY ignore Attributes with an unknown
"Type.Extended-Type".
DeKok & Lior Standards Track [Page 8]
RFC 6929 RADIUS Extensions April 2013
Value
This field is similar to the "Value" field of the Attribute format
defined in [RFC2865] Section 5. The format of the data MUST be a
valid RADIUS data type.
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" field.
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 "Long Extended Type" format MUST 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. Long Extended Type
This section defines a new Attribute format, called "Long Extended
Type". 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| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
This field is identical to the Type field of the Attribute format
defined in [RFC2865] Section 5.
Length
The Length field is one octet and indicates the length of this
Attribute, including the Type, Length, Extended-Type, and "Value"
fields. Permitted values are between 5 and 255. If a client or
DeKok & Lior Standards Track [Page 9]
RFC 6929 RADIUS Extensions April 2013
server receives a "Long Extended Type" with a Length of 2, 3, or
4, then that Attribute MUST be considered to be an "invalid
attribute" and handled as per Section 2.8, below.
Note that this Length is limited to the length of this fragment.
There is no field that gives an explicit value for the total size
of the fragmented attribute.
Extended-Type
This field is identical to the Extended-Type field defined above
in Section 2.1.
M (More)
The More field is one (1) bit in length and indicates whether or
not the current attribute contains "more" than 251 octets of data.
The More field MUST be clear (0) if the Length field has a value
of less than 255. The More field MAY be set (1) if the Length
field has a value of 255.
If the More field is set (1), it indicates that the "Value" field
has been fragmented across multiple RADIUS attributes. When the
More field is set (1), the Attribute MUST have a Length field of
value 255, 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 field set (1).
That is, a packet containing a fragmented attribute needs to
contain all fragments of the Attribute, and those fragments need
to be contiguous in the packet. RADIUS does not support
inter-packet fragmentation, which means that fragmenting an
attribute across multiple packets is impossible.
If a client or server receives an attribute fragment with the
"More" field set (1) but for which no subsequent fragment can be
found, then the fragmented attribute is considered to be an
"invalid attribute" and handled as per Section 2.8, below.
Reserved
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.
DeKok & Lior Standards Track [Page 10]
RFC 6929 RADIUS Extensions April 2013
Future specifications may define additional meaning for this
field. Implementations therefore MUST NOT treat this field as
invalid if it is non-zero.
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 a value of less than 255), or it
may contain a fragment of data.
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" field.
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. If the reassembled data does
not match the expected format, all fragments MUST be treated as
"invalid attributes", and the reassembled data MUST be discarded.
We note that the maximum size of a fragmented attribute is limited
only by the RADIUS packet length limitation (i.e., 4096 octets,
not counting various headers and overhead). Implementations MUST
be able to handle the case where one fragmented attribute
completely fills the packet.
This definition increases the RADIUS Attribute Type space as above
but also provides for transport of Attributes that could contain more
than 253 octets of data.
Note that [RFC2865] Section 5 says:
If multiple Attributes with the same Type are present, the order
of Attributes with the same Type MUST be preserved by any proxies.
The order of Attributes of different Types is not required to be
preserved. A RADIUS server or client MUST NOT have any
dependencies on the order of attributes of different types. A
RADIUS server or client MUST NOT require attributes of the same
type to be contiguous.
These requirements also apply to the "Long Extended Type" Attribute,
including fragments. Implementations MUST be able to process
non-contiguous fragments -- that is, fragments that are mixed
DeKok & Lior Standards Track [Page 11]
RFC 6929 RADIUS Extensions April 2013
together with other attributes of a different Type. This will allow
them to accept packets, so long as the Attributes can be correctly
decoded.
2.3. TLV Data Type
We define a new data type in RADIUS, called "tlv". The "tlv" data
type is an encapsulation layer that 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 reuses 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 TLV-Type field is one octet. Up-to-date values of this field
are specified according to the policies and rules described in
Section 10. Values 254-255 are "Reserved" for use by future
extensions to RADIUS. The value 26 has no special meaning and
MUST NOT be treated as a Vendor-Specific Attribute.
As with the Extended-Type field defined above, the TLV-Type is
meaningful only within the 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-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".
A RADIUS proxy SHOULD forward Attributes with an unknown
"TLV-Type" verbatim.
DeKok & Lior Standards Track [Page 12]
RFC 6929 RADIUS Extensions April 2013
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 that
encapsulates that TLV MUST be considered to be an "invalid
attribute" and handled as per Section 2.8, below.
TLV-Value
The TLV-Value field is one or more octets and contains information
specific to the Attribute. The format and length of the TLV-Value
field are determined by the TLV-Type and TLV-Length fields.
The TLV-Value field SHOULD encapsulate a standard RADIUS data
type. Non-standard data types SHOULD NOT be used within TLV-Value
fields. We note that the TLV-Value field MAY also contain one or
more attributes of data type TLV; data type TLV allows for simple
grouping and multiple layers of nesting.
The TLV-Value field is limited to containing 253 or fewer octets
of data. Specifications that require a TLV to contain more than
253 octets of data are incompatible with RADIUS and need to be
redesigned. Specifications that require the transport of empty
"Value"s (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
nesting.
Vendors MAY use attributes of type "TLV" in any Vendor-Specific
Attribute. It is RECOMMENDED to use type "TLV" for VSAs, in
preference to any other format.
If multiple TLVs with the same TLV-Type are present, the order of
TLVs with the same TLV-Type MUST be preserved by any proxies. The
order of TLVs of different TLV-Types is not required to be preserved.
A RADIUS server or client MUST NOT have any dependencies on the order
of TLVs of different TLV-Types. A RADIUS server or client MUST NOT
require TLVs of the same TLV-Type to be contiguous.
DeKok & Lior Standards Track [Page 13]
RFC 6929 RADIUS Extensions April 2013
The interpretation of multiple TLVs of the same TLV-Type MUST be that
of a logical "and", unless otherwise specified. That is, multiple
TLVs are interpreted as specifying an unordered set of values.
Specifications SHOULD NOT define TLVs to be interpreted as a logical
"or". Doing so would mean that a RADIUS client or server would make
an arbitrary and non-deterministic choice among the values.
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
overfill the "container" TLV, the "container" TLV MUST be considered
to be an "invalid attribute" and handled as described in Section 2.8,
below.
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. They have not been demonstrated to be necessary in
practice, and they appear to make implementations more complex.
Reception of packets with such deeply nested TLVs may indicate
implementation errors or deliberate attacks. Where implementations
do not support deep nesting of TLVs, it is RECOMMENDED that the
unsupported layers are treated as "invalid attributes".
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 that
permits the EVS-Value field of an Attribute to contain a Vendor-Id,
followed by an EVS-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 for use in attributes that carry vendor-
specific information, as is done with the Vendor-Specific Attribute
(Attribute number 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.
DeKok & Lior Standards Track [Page 14]
RFC 6929 RADIUS Extensions April 2013
The "evs" data type MAY be used in Attributes having the format of
"Extended Type" or "Long Extended Type". 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
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EVS-Type | EVS-Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Vendor-Id
The 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] of the vendor in network byte order.
EVS-Type
The EVS-Type field is one octet. Values are assigned at the sole
discretion of the vendor.
EVS-Value
The EVS-Value field is one or more octets. It SHOULD encapsulate
a standard RADIUS data type. Using non-standard data types is NOT
RECOMMENDED. We note that the EVS-Value 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. While we recognize that vendors have
complete control over the contents and format of the EVS-Value
field, we recommend 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 EVS-Value
field is implicit and is determined by taking the "Length" of the
encapsulating RADIUS attribute and then subtracting the length of the
DeKok & Lior Standards Track [Page 15]
RFC 6929 RADIUS Extensions April 2013
Attribute header (2 octets), the "Extended Type" (1 octet), the
Vendor-Id (4 octets), and the EVS-Type (1 octet). That is, for
"Extended Type" Attributes the length of the EVS-Value field is eight
(8) less than the value of the Length field, and for "Long Extended
Type" Attributes the length of the EVS-Value field is nine (9) less
than the value of the Length field.
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 that can count past 2^32. The expected use
of 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 can 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 "Long Extended Type"
Attributes, the Length field MUST be set to twelve (12).
2.6. Vendor-Id Field
We define the Vendor-Id field of Vendor-Specific Attributes
to encompass the entire 4 octets of the Vendor field.
[RFC2865] Section 5.26 defined it to be 3 octets, with the fourth
octet being zero. This change has no immediate impact on RADIUS, as
the maximum Private Enterprise Code defined is still within 16 bits.
DeKok & Lior Standards Track [Page 16]
RFC 6929 RADIUS Extensions April 2013
However, it is best to make advance preparations for changes in the
protocol. As such, it is RECOMMENDED that all implementations
support four (4) octets for the Vendor-Id field, instead of
three (3).
2.7. Attribute Naming and Type Identifiers
Attributes have traditionally been identified by a unique name and
number. For example, the Attribute "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.
2.7.1. 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.
It is therefore RECOMMENDED that specifications give names to
Attributes that attempt to be globally unique across all RADIUS
Attributes. It is RECOMMENDED that a vendor use its name as a unique
prefix for attribute names, e.g., Livingston-IP-Pool instead of
IP-Pool. It is RECOMMENDED that implementations enforce uniqueness
on names; not doing so would lead to ambiguity and problems.
We recognize that these suggestions 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 called "Time-Zone",
"Time-Day", "Time-Hour", "Time-Minute", etc.
DeKok & Lior Standards Track [Page 17]
RFC 6929 RADIUS Extensions April 2013
2.7.2. 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, an 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".
2.7.3. TLV Identifiers
We can extend the Attribute reference scheme defined above for TLVs.
This is done by leveraging the "dotted number" notation. As above,
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 repeated 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, with TLV-Type number four (4).
2.7.4. 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 32-bit Vendor-Id, and possibly
additional VSAs. Where the VSAs follow the format recommended
by [RFC2865] Section 5.26, a VSA can be identified as
"26.Vendor-Id.Vendor-Type".
DeKok & Lior Standards Track [Page 18]
RFC 6929 RADIUS Extensions April 2013
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, but it cannot be uniquely identified by name, as other
vendors may have used the same name.
Note that there are few restrictions on the size of the numerical
values in this notation. The Vendor-Id is a 32-bit number, and the
VSA may have been assigned from a 16-bit Vendor-Specific Attribute
Type space. Implementations SHOULD be capable of handling 32-bit
numbers at each level of the "dotted number" notation.
For example, the company USR has historically used Vendor-Id 429 and
has defined a "Version-Id" attribute as number 32768. This VSA can
be uniquely identified as 26.429.32768 but again cannot be uniquely
identified by name.
Where a VSA is a TLV, the "dotted number" notation can be used as
above: 26.Vendor-Id.Vendor-Type.TLV1.TLV2.TLV3, where the "TLVn"
values are the numerical values assigned by the vendor to the
different nested TLVs.
2.8. Invalid Attributes
The term "invalid attribute" is new to this specification. It is
defined to mean that the Length field of an Attribute permits the
packet to be accepted as not being "malformed". However, the "Value"
field of the Attribute does not follow the format required by the
data type defined for that Attribute, and therefore the Attribute is
"malformed". In order to distinguish the two cases, we refer to
"malformed" packets and "invalid attributes".
For example, an implementation receives a packet that is well formed.
That packet contains an Attribute allegedly of data type "address"
but that has Length not equal to four. In that situation, the packet
is well formed, but the Attribute is not. Therefore, it is an
"invalid attribute".
A similar analysis can be performed when an attribute carries TLVs.
The encapsulating attribute may be well formed, but the TLV may be an
"invalid attribute". The existence of an "invalid attribute" in a
packet or attribute MUST NOT result in the implementation discarding
the entire packet or treating the packet as a negative
acknowledgment. Instead, only the "invalid attribute" is treated
specially.
When an implementation receives an "invalid attribute", it SHOULD be
silently discarded, except when the implementation is acting as a
proxy (see Section 5.2 for discussion of proxy servers). If it is
DeKok & Lior Standards Track [Page 19]
RFC 6929 RADIUS Extensions April 2013
not discarded, it MUST NOT be handled in the same manner as a well-
formed attribute. For example, receiving an Attribute of data type
"address" containing either less than four octets or more than
four octets of data means that the Attribute MUST NOT be treated as
being of data type "address". The reason here is that if the
Attribute does not carry an IPv4 address, the receiver has no idea
what format the data is in, and it is therefore not an IPv4 address.
For Attributes of type "Long Extended Type", an Attribute is
considered to be an "invalid attribute" when it does not match the
criteria set out in Section 2.2, above.
For Attributes of type "TLV", an Attribute is considered to be an
"invalid attribute" when the TLV-Length field allows the
encapsulating Attribute to be parsed but the TLV-Value field does not
match the criteria for that TLV. Implementations SHOULD NOT treat
the "invalid attribute" property as being transitive. That is, the
Attribute encapsulating the "invalid attribute" SHOULD NOT be treated
as an "invalid attribute". That encapsulating Attribute might
contain multiple TLVs, only one of which is an "invalid attribute".
However, a TLV definition may require particular sub-TLVs to be
present and/or to have specific values. If a sub-TLV is missing or
contains incorrect value(s), or if it is an "invalid attribute", then
the encapsulating TLV SHOULD be treated as an "invalid attribute".
This requirement ensures that strongly connected TLVs are either
handled as a coherent whole or ignored entirely.
It is RECOMMENDED that Attributes with unknown Type, Extended-Type,
TLV-Type, or EVS-Type are treated as "invalid attributes". This
recommendation is compatible with the suggestion in [RFC2865]
Section 5 that implementations "MAY ignore Attributes with an
unknown Type".
DeKok & Lior Standards Track [Page 20]
RFC 6929 RADIUS Extensions April 2013
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 "Long Extended Type", 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 Long-Extended-Type-1
246 Long-Extended-Type-2
The rest of this section gives detailed definitions 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
DeKok & Lior Standards Track [Page 21]
RFC 6929 RADIUS Extensions April 2013
Extended-Type
The Extended-Type field is one octet. Up-to-date values of this
field are specified in the 241.{1-255} RADIUS Attribute Type
space, according to the policies and rules described in
Section 10. Further definition of this field is given in
Section 2.1, above.
Value
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" 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 in the 242.{1-255} RADIUS Attribute Type
space, according to the policies and rules described in
Section 10. Further definition of this field is given in
Section 2.1, above.
DeKok & Lior Standards Track [Page 22]
RFC 6929 RADIUS Extensions April 2013
Value
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" 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 in the 243.{1-255} RADIUS Attribute Type
space, according to the policies and rules described in
Section 10. Further definition of this field is given in
Section 2.1, above.
Value
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" field.
DeKok & Lior Standards Track [Page 23]
RFC 6929 RADIUS Extensions April 2013
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 in the 244.{1-255} RADIUS Attribute Type
space, according to the policies and rules described in
Section 10. Further definition of this field is given in
Section 2.1, above.
Value
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the Value Field.
DeKok & Lior Standards Track [Page 24]
RFC 6929 RADIUS Extensions April 2013
3.5. Long-Extended-Type-1
Description
This attribute encapsulates attributes of the "Long Extended Type"
format, in the RADIUS Attribute Type space of 245.{1-255}.
A summary of the Long-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 |M| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
245 for Long-Extended-Type-1
Length
>= 5
Extended-Type
The Extended-Type field is one octet. Up-to-date values of this
field are specified in the 245.{1-255} RADIUS Attribute Type
space, according to the policies and rules described in
Section 10. Further definition of this field is given in
Section 2.1, above.
M (More)
The More field 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.
Reserved
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.
DeKok & Lior Standards Track [Page 25]
RFC 6929 RADIUS Extensions April 2013
Value
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" field.
3.6. Long-Extended-Type-2
Description
This attribute encapsulates attributes of the "Long Extended Type"
format, in the RADIUS Attribute Type space of 246.{1-255}.
A summary of the Long-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 |M| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
246 for Long-Extended-Type-2
Length
>= 5
Extended-Type
The Extended-Type field is one octet. Up-to-date values of this
field are specified in the 246.{1-255} RADIUS Attribute Type
space, according to the policies and rules described in
Section 10. Further definition of this field is given in
Section 2.1, above.
M (More)
The More field 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.
DeKok & Lior Standards Track [Page 26]
RFC 6929 RADIUS Extensions April 2013
Reserved
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.
Value
The "Value" field is one or more octets.
Implementations supporting this specification MUST use the
identifier of "Type.Extended-Type" to determine the interpretation
of the "Value" field.
4. Vendor-Specific Attributes
We define six new attributes that 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 using "Long
Extended Type" format, with Type codes (245.26, 246.26), which are of
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 detailed definitions for each
Attribute based on the above summary.
DeKok & Lior Standards Track [Page 27]
RFC 6929 RADIUS Extensions April 2013
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type.Extended-Type
241.26 for Extended-Vendor-Specific-1
Length
>= 9
Vendor-Id
The 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] 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.
Value
The "Value" 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.
DeKok & Lior Standards Track [Page 28]
RFC 6929 RADIUS Extensions April 2013
The length of the "Value" field is eight (8) less than 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 "Value" 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | Vendor-Id ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Vendor-Id (cont) | Vendor-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type.Extended-Type
242.26 for Extended-Vendor-Specific-2
Length
>= 9
Vendor-Id
The 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] 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.
DeKok & Lior Standards Track [Page 29]
RFC 6929 RADIUS Extensions April 2013
Value
The "Value" 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 "Value" field is eight (8) less than 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 "Value" field.
4.3. Extended-Vendor-Specific-3
Description
This attribute defines a RADIUS Type Code of 243.26, 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type.Extended-Type
243.26 for Extended-Vendor-Specific-3
Length
>= 9
Vendor-Id
The 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] of the vendor in network byte order.
DeKok & Lior Standards Track [Page 30]
RFC 6929 RADIUS Extensions April 2013
Vendor-Type
The Vendor-Type field is one octet. Values are assigned at the
sole discretion of the vendor.
Value
The "Value" 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 "Value" field is eight (8) less than 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 "Value" field.
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-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 | Vendor-Id ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Vendor-Id (cont) | Vendor-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type.Extended-Type
244.26 for Extended-Vendor-Specific-4
Length
>= 9
DeKok & Lior Standards Track [Page 31]
RFC 6929 RADIUS Extensions April 2013
Vendor-Id
The 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] 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.
Value
The "Value" 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 "Value" field is eight (8) less than 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 "Value" 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| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-Type | Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DeKok & Lior Standards Track [Page 32]
RFC 6929 RADIUS Extensions April 2013
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 "Value" field only.
M (More)
The More field 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.
Reserved
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 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] 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.
Value
The "Value" 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 "Value" field.
DeKok & Lior Standards Track [Page 33]
RFC 6929 RADIUS Extensions April 2013
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| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-Type | Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 "Value" field only.
M (More)
The More field 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.
Reserved
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.
DeKok & Lior Standards Track [Page 34]
RFC 6929 RADIUS Extensions April 2013
Vendor-Id
The 4 octets of the Vendor-Id field are the Network Management
Private Enterprise Code [PEN] 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.
Value
The "Value" 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 "Value" field.
5. Compatibility with Traditional RADIUS
There are a number of potential compatibility issues with traditional
RADIUS, as defined in [RFC6158] and earlier. 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
antisocial 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 that indicates which type of attributes are being
sent from the client. If the flag is set to "Non-Standard
Attributes", the conflicting attributes can be interpreted as being
improperly defined Vendor-Specific Attributes. If the flag is set to
DeKok & Lior Standards Track [Page 35]
RFC 6929 RADIUS Extensions April 2013
"IETF Attributes", 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 reuse the above flag
to determine which types 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
usually have a configuration setting that 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 implementers 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 that they do not understand (i.e.,
attributes for which they have no local dictionary definitions).
DeKok & Lior Standards Track [Page 36]
RFC 6929 RADIUS Extensions April 2013
This practice is NOT RECOMMENDED. Proxy servers SHOULD forward
attributes, even attributes that they do not understand or that are
not in a local dictionary. When forwarded, these attributes SHOULD
be sent verbatim, with no modifications or changes. This requirement
includes "invalid attributes", as there may be some other system in
the network that understands them.
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 that 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 during testing performed in 2010 via the EDUcation ROAMing
(EDUROAM) service (A. DeKok, unpublished data), many proxies do not
follow these practices for unknown Attributes. Some proxies filter
out unknown attributes or attributes that 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), and the
rest (63%, 44/70) follow 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 that 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.
6. Guidelines
This specification proposes a number of changes to RADIUS and
therefore requires a set of guidelines, as has been done in
[RFC6158]. These guidelines include suggestions related to design,
interaction with IANA, usage, and implementation of attributes using
the new formats.
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.
The recommendations for the use of the new data types and Attribute
formats are given below.
DeKok & Lior Standards Track [Page 37]
RFC 6929 RADIUS Extensions April 2013
6.2. Guidelines for Simple Data Types
[RFC6158] Section A.2.1 says in part:
* Unsigned integers of size other than 32 bits. SHOULD be replaced
by an unsigned integer of 32 bits. There is insufficient
justification to define a new size of integer.
We update that specification to permit unsigned integers of 64 bits,
for the reasons defined above in Section 2.5. The updated text is as
follows:
* Unsigned integers of size other than 32 or 64 bits. SHOULD be
replaced by an unsigned integer of 32 or 64 bits. There is
insufficient justification to define a new size of integer.
That section later continues with the following list item:
* Nested attribute-value pairs (AVPs). Attributes should be defined
in a flat typespace.
We update that specification to permit nested TLVs, as defined in
this document:
* Nested attribute-value pairs (AVPs) using the extended Attribute
format MAY be used. All other nested AVP or TLV formats MUST NOT
be used.
The [RFC6158] recommendations for "basic" data types apply to the
three types listed above. All other recommendations given in
[RFC6158] for "basic" data types remain unchanged.
6.3. Guidelines for Complex Data Types
[RFC6158] Section 2.1 says:
Complex data types MAY be used in situations where they reduce
complexity in non-RADIUS systems or where using the basic data
types would be awkward (such as where grouping would be required
in order to link related attributes).
Since the extended Attribute format allows for grouping of complex
types via TLVs, the guidelines for complex data types need to be
updated as follows:
[RFC6158], Section 3.2.4, describes situations in which complex
data types might be appropriate. They SHOULD NOT be used even in
those situations, without careful consideration of the described
DeKok & Lior Standards Track [Page 38]
RFC 6929 RADIUS Extensions April 2013
limitations. In all other cases not covered by the complex data
type exceptions, complex data types MUST NOT be used. Instead,
complex data types MUST be decomposed into TLVs.
The checklist in [RFC6158] Appendix A.2.2 is similarly updated to add
a new requirement at the top of that section, as follows:
Does the Attribute
* define a complex type that can be represented via TLVs?
If so, this data type MUST be represented via TLVs.
Note that this requirement does not override [RFC6158] Appendix A.1,
which permits the transport of complex types in certain situations.
All other recommendations given in [RFC6158] for "complex" data types
remain unchanged.
6.4. Design Guidelines for the New Types
This section gives design guidelines for specifications defining
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.
* [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 was not recommended in [RFC6158], but their
utility is now evident.
* Any attribute that is allocated from the long extended space of
data type "text", "string", or "tlv" can potentially carry more
than 251 octets of data. Specifications defining such attributes
SHOULD define a maximum length to guide implementations.
All other recommendations given in [RFC6158] for attribute design
guidelines apply to attributes using the short extended space and
long extended space.
DeKok & Lior Standards Track [Page 39]
RFC 6929 RADIUS Extensions April 2013
6.5. TLV Guidelines
The following items give design 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) 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 totals less than 247 octets of data, the specifications
SHOULD request allocation from the short extended space.
* Where a group of TLVs is loosely defined or is expected to change,
the specifications SHOULD request allocation from the long extended
space.
All other recommendations given in [RFC6158] for attribute design
guidelines apply to attributes using the TLV format.
6.6. Allocation Request Guidelines
The following items give guidelines for allocation requests made in a
RADIUS specification.
* Discretion is recommended when requesting allocation of attributes.
The new space is much larger than the old one, but it is not
infinite.
* Specifications that allocate many attributes MUST NOT request that
allocation be made from the standard space. That space is under
allocation pressure, and the extended space is more suitable for
large allocations. As a guideline, we suggest that one
specification allocating twenty percent (20%) or more of the
standard space would meet the above criteria.
* Specifications that allocate many related attributes SHOULD define
one or more TLVs to contain related attributes.
DeKok & Lior Standards Track [Page 40]
RFC 6929 RADIUS Extensions April 2013
* Specifications SHOULD request allocation from a specific space.
The IANA considerations given in Section 10, below, give
instructions to IANA, but authors should assist IANA where
possible.
* Specifications of an attribute that encodes 252 octets or less of
data MAY request allocation from the short extended space.
* Specifications of an attribute that always encode less than
253 octets of data MUST NOT request allocation from the long
extended space. The standard space or the short extended space
MUST be used instead.
* Specifications of an attribute that encodes 253 octets or more of
data MUST request allocation from the long extended space.
* When the extended space is nearing exhaustion, a new specification
will have to be written that requests allocation of one or more
RADIUS attributes from the "Reserved" portion of the standard
space, values 247-255, using an appropriate format ("Short Extended
Type", or "Long Extended Type").
An allocation request made in a specification SHOULD use one of the
following formats when allocating an attribute type code:
* TBDn - request allocation of an attribute from the standard space.
The value "n" should be 1 or more, to track individual attributes
that are to be allocated.
* SHORT-TBDn - request allocation of an attribute from the short
extended space. The value "n" should be 1 or more, to track
individual attributes that are to be allocated.
* LONG-TBDn - request allocation of an attribute from the long
extended space. The value "n" should be 1 or more, to track
individual attributes that are to be allocated.
These guidelines should help specification authors and IANA
communicate effectively and clearly.
6.7. Allocation Request Guidelines for TLVs
Specifications may allocate a new attribute of type TLV and at the
same time allocate sub-Attributes within that TLV. These
specifications SHOULD request allocation of specific values for the
sub-TLV. The "dotted number" notation MUST be used.
DeKok & Lior Standards Track [Page 41]
RFC 6929 RADIUS Extensions April 2013
For example, a specification may request allocation of a TLV as
SHORT-TBD1. Within that attribute, it could request allocation of
three sub-TLVs, as SHORT-TBD1.1, SHORT-TBD1.2, and SHORT-TBD1.3.
Specifications may request allocation of additional sub-TLVs within
an existing attribute of type TLV. Those specifications SHOULD use
the "TBDn" format for every entry in the "dotted number" notation.
For example, a specification may request allocation within an
existing TLV, with "dotted number" notation MM.NN. Within that
attribute, the specification could request allocation of three
sub-TLVs, as MM.NN.TBD1, MM.NN.TBD2, and MM.NN.TBD3.
6.8. Implementation Guidelines
* RADIUS client implementations SHOULD support this specification in
order to permit the easy deployment of specifications using the
changes defined herein.
* RADIUS server implementations SHOULD support this specification in
order to permit the easy deployment of specifications using the
changes defined herein.
* RADIUS proxy servers MUST follow the specifications in Section 5.2.
6.9. 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. The changes to RADIUS
are relatively small and are likely to quickly be used in new
specifications.
7. Rationale for This Design
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 unworkable in practice. We do not
otherwise explain here why earlier proposals did not obtain working
group consensus.
DeKok & Lior Standards Track [Page 42]
RFC 6929 RADIUS Extensions April 2013
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 "Long Extended Type"
format is awkward, and the 7 Reserved bits will likely never be used
for anything.
7.1. Attribute Audit
An audit of almost five thousand publicly available attributes [ATTR]
(2010) 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 all other data types, including complex data types and
data types transporting opaque data.
We see that over half of the Attributes encode less than 16 octets of
data. It is therefore important to have an extension mechanism that
adds as little as possible to the size of these attributes. Another
result is that the overwhelming majority of attributes use simple
data types.
Of the Attributes defined above, 177 were declared as being inside of
a TLV. This is approximately 4% of the total. We did not
investigate whether additional attributes were defined in a flat
namespace but could have been defined as being inside of a TLV. We
expect that the number could be as high as 10% of attributes.
DeKok & Lior Standards Track [Page 43]
RFC 6929 RADIUS Extensions April 2013
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 such as EAP-Message.
The results of this audit and analysis are reflected in the design of
the extended attributes. The extended format has minimal overhead,
permits TLVs, and has support for "long" attributes.
8. Diameter Considerations
The Attribute formats defined in this specification need to be
transported in Diameter. While Diameter supports attributes longer
than 253 octets and grouped attributes, we do not use that
functionality here. Instead, we define the simplest possible
encapsulation method.
The new formats MUST be treated the same as traditional RADIUS
attributes when converting from RADIUS to Diameter, or vice versa.
That is, the new attribute space is not converted to any "extended"
Diameter attribute space. Fragmented attributes are not converted to
a single long Diameter attribute. The new EVS data types are not
converted to Diameter attributes with the "V" bit set.
In short, this document mandates no changes for existing RADIUS-to-
Diameter or Diameter-to-RADIUS gateways.
9. 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, but only attributes.
DeKok & Lior Standards Track [Page 44]
RFC 6929 RADIUS Extensions April 2013
The examples are given using a domain-specific language implemented
by the program given in Appendix A of this document. The language is
line oriented and composed of a sequence of lines matching the ABNF
grammar ([RFC5234]) given below:
Identifier = 1*DIGIT *( "." 1*DIGIT )
HEXCHAR = HEXDIG HEXDIG
STRING = DQUOTE 1*CHAR DQUOTE
TLV = "{" SP 1*DIGIT SP DATA SP "}"
DATA = (HEXCHAR *(SP HEXCHAR)) / (TLV *(SP TLV)) / STRING
LINE = Identifier SP DATA
The program has additional restrictions on its input that are not
reflected in the above grammar. For example, the portions of the
identifier that 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
comprehensibility 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 that 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 fields; 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 that contains non-UTF8 data or a
Framed-IP-Address that 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", "Reserved", "Vendor-Id",
"Vendor-Type", and "Vendor-Length". It encodes RADIUS attribute data
types "evs" and "tlv". It can therefore be used to encode example
attributes from inputs that are human readable.
We do not give examples of "invalid attributes". We also note that
the examples show format, rather than 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.
DeKok & Lior Standards Track [Page 45]
RFC 6929 RADIUS Extensions April 2013
The examples given below are strictly for demonstration purposes only
and do not provide a standard of any kind.
9.1. Extended Type
The following is a series of examples of the "Extended Type" format.
Attribute encapsulating textual data:
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
DeKok & Lior Standards Track [Page 46]
RFC 6929 RADIUS Extensions April 2013
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
9.2. Long Extended Type
The following is a series of examples of the "Long Extended Type"
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
DeKok & Lior Standards Track [Page 47]
RFC 6929 RADIUS Extensions April 2013
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 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 "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbcccccccccccccccccccc
ccccccccccc"
-> 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
DeKok & Lior Standards Track [Page 48]
RFC 6929 RADIUS Extensions April 2013
Below is an example of an 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 field
set, and it carries the Vendor-Id and Vendor-Type. The second
attribute has the More field 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 "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
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 18 1a 00 bb
bb bb bb bb cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
DeKok & Lior Standards Track [Page 49]
RFC 6929 RADIUS Extensions April 2013
10. IANA Considerations
This document updates [RFC3575] in that it adds new IANA
considerations for RADIUS attributes. These considerations modify
and extend the IANA considerations for RADIUS, rather than replacing
them.
The IANA considerations of this document are limited to the "RADIUS
Attribute Types" registry. Some Attribute Type values that were
previously marked "Reserved" are now allocated, and the registry is
extended from a simple 8-bit array to a tree-like structure, up to a
maximum depth of 125 nodes. Detailed instructions are given below.
10.1. Attribute Allocations
IANA has moved the following Attribute Type values from "Reserved" to
"Allocated" with the corresponding names:
* 241 Extended-Type-1
* 242 Extended-Type-2
* 243 Extended-Type-3
* 244 Extended-Type-4
* 245 Long-Extended-Type-1
* 246 Long-Extended-Type-2
These values serve as an encapsulation layer for the new RADIUS
Attribute Type tree.
10.2. RADIUS Attribute Type Tree
Each of the Attribute Type values allocated above extends the "RADIUS
Attribute Types" to an N-ary tree, via a "dotted number" notation.
Allocation of an Attribute Type value "TYPE" using the new "Extended
Type" format results in allocation of 255 new Attribute Type values
of format "TYPE.1" through "TYPE.255". Value twenty-six (26) is
assigned as "Extended-Vendor-Specific-*". Values "TYPE.241" through
"TYPE.255" are marked "Reserved". All other values are "Unassigned".
DeKok & Lior Standards Track [Page 50]
RFC 6929 RADIUS Extensions April 2013
The initial set of Attribute Type values and names assigned by this
document is given below.
* 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
* 242.{241-255} Reserved
* 243 Extended-Attribute-3
* 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
* 246.26 Extended-Vendor-Specific-6
* 246.{27-240} Unassigned
* 246.{241-255} Reserved
As per [RFC5226], the values marked "Unassigned" above are available
for assignment by IANA in future RADIUS specifications. The values
marked "Reserved" are reserved for future use.
The Extended-Vendor-Specific spaces (TYPE.26) are for Private Use,
and allocations are not managed by IANA.
Allocation of Reserved entries in the extended space requires
Standards Action.
All other allocations in the extended space require IETF Review.
DeKok & Lior Standards Track [Page 51]
RFC 6929 RADIUS Extensions April 2013
10.3. Allocation Instructions
This section defines what actions IANA needs to take when allocating
new attributes. Different actions are required when allocating
attributes from the standard space, attributes of the "Extended Type"
format, attributes of the "Long Extended Type" format, preferential
allocations, attributes of data type TLV, attributes within a TLV,
and attributes of other data types.
10.3.1. Requested Allocation from the Standard Space
Specifications can request allocation of an Attribute from within the
standard space (e.g., Attribute Type Codes 1 through 255), subject to
the considerations of [RFC3575] and this document.
10.3.2. Requested Allocation from the Short Extended Space
Specifications can request allocation of an Attribute that requires
the format "Extended Type", by specifying the short extended space.
In that case, IANA should assign the lowest Unassigned number from
the Attribute Type space with the relevant format.
10.3.3. Requested Allocation from the Long Extended Space
Specifications can request allocation of an Attribute that requires
the format "Long Extended Type", by specifying the extended space
(long). In that case, IANA should assign the lowest Unassigned
number from the Attribute Type space with the relevant format.
10.3.4. Allocation Preferences
Specifications that make no request for allocation from a specific
type space should have Attributes allocated using the following
criteria:
* When the standard space has no more Unassigned attributes, all
allocations should be performed from the extended space.
* Specifications that allocate a small number of attributes (i.e.,
less than ten) should have all allocations made from the standard
space.
* Specifications that would allocate more than twenty percent of the
remaining standard space attributes should have all allocations
made from the extended space.
* Specifications that request allocation of an attribute of data type
TLV should have that attribute allocated from the extended space.
DeKok & Lior Standards Track [Page 52]
RFC 6929 RADIUS Extensions April 2013
* Specifications that request allocation of an attribute that can
transport 253 or more octets of data should have that attribute
allocated from within the long extended space. We note that
Section 6.5 above makes recommendations related to this allocation.
There is otherwise no requirement that all attributes within a
specification be allocated from one type space or another.
Specifications can simultaneously allocate attributes from both the
standard space and the extended space.
10.3.5. Extending the Type Space via the TLV Data Type
When specifications request allocation of an attribute of data type
TLV, that allocation extends the Attribute Type tree by one more
level. Allocation of an Attribute Type value "TYPE.TLV", with data
type TLV, results in allocation of 255 new Attribute Type values, of
format "TYPE.TLV.1" through "TYPE.TLV.255". Values 254-255 are
marked "Reserved". All other values are "Unassigned". Value 26 has
no special meaning.
For example, if a new attribute "Example-TLV" of data type TLV is
assigned the identifier "245.1", then the extended tree will be
allocated 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, as discussed below.
10.3.6. Allocation within a TLV
Specifications can request allocation of Attribute Type values within
an Attribute of data type TLV. The encapsulating TLV can be
allocated in the same specification, or it can have been previously
allocated.
Specifications need to request allocation within a specific Attribute
Type value (e.g., "TYPE.TLV.*"). Allocations are performed from the
smallest Unassigned value, proceeding to the largest Unassigned
value.
DeKok & Lior Standards Track [Page 53]
RFC 6929 RADIUS Extensions April 2013
Where the Attribute being allocated is of data type TLV, the
Attribute Type tree is extended by one level, as given in the
previous section. Allocations can then be made within that level.
10.3.7. Allocation of Other Data Types
Attribute Type value allocations are otherwise allocated from the
smallest Unassigned value, proceeding to the largest Unassigned
value, e.g., starting from 241.1, proceeding through 241.255, then to
242.1, through 242.255, etc.
11. 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]. The security of the RADIUS
protocol is dependent on MD5 [RFC1321], which has security issues as
discussed in [RFC6151]. It is not known if the issues described in
[RFC6151] apply to RADIUS. For other issues, we incorporate by
reference the security considerations of [RFC6158] Section 5.
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.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
[RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575,
July 2003.
DeKok & Lior Standards Track [Page 54]
RFC 6929 RADIUS Extensions April 2013
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6158] DeKok, A., Ed., and G. Weber, "RADIUS Design Guidelines",
BCP 158, RFC 6158, March 2011.
[PEN] IANA, "PRIVATE ENTERPRISE NUMBERS",
<http://www.iana.org/assignments/enterprise-numbers>.
12.2. Informative References
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2868] Zorn, G., Leifer, D., Rubens, A., Shriver, J., Holdrege,
M., and I. Goyret, "RADIUS Attributes for Tunnel Protocol
Support", RFC 2868, June 2000.
[RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic
Hashes in Internet Protocols", RFC 4270, November 2005.
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234,
January 2008.
[RFC6151] Turner, S. and L. Chen, "Updated Security Considerations
for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
RFC 6151, March 2011.
[ATTR] "alandekok/freeradius-server", available from GitHub, data
retrieved September 2010, <http://github.com/alandekok/
freeradius-server/tree/master/share/>.
13. 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.
DeKok & Lior Standards Track [Page 55]
RFC 6929 RADIUS Extensions April 2013
Appendix A. Extended Attribute Generator Program
This section contains "C" program source code that 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 grammar similar to that given in Section 9, 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) 2013 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,
DeKok & Lior Standards Track [Page 56]
RFC 6929 RADIUS Extensions April 2013
* 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;
DeKok & Lior Standards Track [Page 57]
RFC 6929 RADIUS Extensions April 2013
case 'r':
*(output++) = '\r';
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++;
DeKok & Lior Standards Track [Page 58]
RFC 6929 RADIUS Extensions April 2013
length = encode_tlv(p, output, outlen);
if (length == 0) return 0;
return length;
}
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;
}
DeKok & Lior Standards Track [Page 59]
RFC 6929 RADIUS Extensions April 2013
if (*p == '"') {
length = encode_data_string(p, output, outlen);
return length;
}
length = 0;
while (*p) {
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;
}
DeKok & Lior Standards Track [Page 60]
RFC 6929 RADIUS Extensions April 2013
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;
}
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;
}
DeKok & Lior Standards Track [Page 61]
RFC 6929 RADIUS Extensions April 2013
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;
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;
}
DeKok & Lior Standards Track [Page 62]
RFC 6929 RADIUS Extensions April 2013
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;
}
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;
DeKok & Lior Standards Track [Page 63]
RFC 6929 RADIUS Extensions April 2013
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");
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;
DeKok & Lior Standards Track [Page 64]
RFC 6929 RADIUS Extensions April 2013
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;
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;
DeKok & Lior Standards Track [Page 65]
RFC 6929 RADIUS Extensions April 2013
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;
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];
DeKok & Lior Standards Track [Page 66]
RFC 6929 RADIUS Extensions April 2013
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;
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]);
}
DeKok & Lior Standards Track [Page 67]
RFC 6929 RADIUS Extensions April 2013
printf("\n");
}
if (fp != stdin) fclose(fp);
return 0;
}
------------------------------------------------------------
Authors' Addresses
Alan DeKok
Network RADIUS SARL
57bis blvd des Alpes
38240 Meylan
France
EMail: aland@networkradius.com
URI: http://networkradius.com
Avi Lior
EMail: avi.ietf@lior.org
DeKok & Lior Standards Track [Page 68]