Network Working Group C. Rigney
Request for Comments: 2139 Livingston
Obsoletes: 2059 April 1997
Category: Informational
RADIUS Accounting
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Abstract
This document describes a protocol for carrying accounting
information between a Network Access Server and a shared Accounting
Server.
Implementation Note
This memo documents the RADIUS Accounting protocol. There has been
some confusion in the assignment of port numbers for this protocol.
The early deployment of RADIUS Accounting was done using the
erroneously chosen port number 1646, which conflicts with the "sa-
msg-port" service. The officially assigned port number for RADIUS
Accounting is 1813.
Table of Contents
1. Introduction .......................................... 2
1.1 Specification of Requirements ................... 3
1.2 Terminology ..................................... 3
2. Operation ............................................. 4
3. Packet Format ......................................... 5
4. Packet Types .......................................... 7
4.1 Accounting-Request .............................. 7
4.2 Accounting-Response ............................. 8
5. Attributes ............................................ 10
5.1 Acct-Status-Type ................................ 11
5.2 Acct-Delay-Time ................................. 12
5.3 Acct-Input-Octets ............................... 13
5.4 Acct-Output-Octets .............................. 14
5.5 Acct-Session-Id ................................. 14
5.6 Acct-Authentic .................................. 15
5.7 Acct-Session-Time ............................... 16
5.8 Acct-Input-Packets .............................. 16
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5.9 Acct-Output-Packets ............................. 17
5.10 Acct-Terminate-Cause ............................ 18
5.11 Acct-Multi-Session-Id ........................... 20
5.12 Acct-Link-Count ................................. 21
5.13 Table of Attributes ............................. 22
Security Considerations ...................................... 24
References ................................................... 24
Acknowledgements ............................................. 24
Chair's Address .............................................. 24
Author's Address ............................................. 25
1. Introduction
Managing dispersed serial line and modem pools for large numbers of
users can create the need for significant administrative support.
Since modem pools are by definition a link to the outside world, they
require careful attention to security, authorization and accounting.
This can be best achieved by managing a single "database" of users,
which allows for authentication (verifying user name and password) as
well as configuration information detailing the type of service to
deliver to the user (for example, SLIP, PPP, telnet, rlogin).
The RADIUS (Remote Authentication Dial In User Service) document [4]
specifies the RADIUS protocol used for Authentication and
Authorization. This memo extends the use of the RADIUS protocol to
cover delivery of accounting information from the Network Access
Server (NAS) to a RADIUS accounting server.
Key features of RADIUS Accounting are:
Client/Server Model
A Network Access Server (NAS) operates as a client of the
RADIUS accounting server. The client is responsible for
passing user accounting information to a designated RADIUS
accounting server.
The RADIUS accounting server is responsible for receiving the
accounting request and returning a response to the client
indicating that it has successfully received the request.
The RADIUS accounting server can act as a proxy client to other
kinds of accounting servers.
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Network Security
Transactions between the client and RADIUS accounting server
are authenticated through the use of a shared secret, which is
never sent over the network.
Extensible Protocol
All transactions are comprised of variable length Attribute-
Length-Value 3-tuples. New attribute values can be added
without disturbing existing implementations of the protocol.
1.1. Specification of Requirements
In this document, several words are used to signify the requirements
of the specification. These words are often capitalized.
MUST This word, or the adjective "required", means that the
definition is an absolute requirement of the specification.
MUST NOT This phrase means that the definition is an absolute
prohibition of the specification.
SHOULD This word, or the adjective "recommended", means that there
may exist valid reasons in particular circumstances to
ignore this item, but the full implications must be
understood and carefully weighed before choosing a
different course.
MAY This word, or the adjective "optional", means that this
item is one of an allowed set of alternatives. An
implementation which does not include this option MUST be
prepared to interoperate with another implementation which
does include the option.
1.2. Terminology
This document uses the following terms:
service The NAS provides a service to the dial-in user, such as PPP
or Telnet.
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session Each service provided by the NAS to a dial-in user
constitutes a session, with the beginning of the session
defined as the point where service is first provided and
the end of the session defined as the point where service
is ended. A user may have multiple sessions in parallel or
series if the NAS supports that, with each session
generating a separate start and stop accounting record with
its own Acct-Session-Id.
silently discard
This means the implementation discards the packet without
further processing. The implementation SHOULD provide the
capability of logging the error, including the contents of
the silently discarded packet, and SHOULD record the event
in a statistics counter.
2. Operation
When a client is configured to use RADIUS Accounting, at the start of
service delivery it will generate an Accounting Start packet
describing the type of service being delivered and the user it is
being delivered to, and will send that to the RADIUS Accounting
server, which will send back an acknowledgement that the packet has
been received. At the end of service delivery the client will
generate an Accounting Stop packet describing the type of service
that was delivered and optionally statistics such as elapsed time,
input and output octets, or input and output packets. It will send
that to the RADIUS Accounting server, which will send back an
acknowledgement that the packet has been received.
The Accounting-Request (whether for Start or Stop) is submitted to
the RADIUS accounting server via the network. It is recommended that
the client continue attempting to send the Accounting-Request packet
until it receives an acknowledgement, using some form of backoff. If
no response is returned within a length of time, the request is re-
sent a number of times. The client can also forward requests to an
alternate server or servers in the event that the primary server is
down or unreachable. An alternate server can be used either after a
number of tries to the primary server fail, or in a round-robin
fashion. Retry and fallback algorithms are the topic of current
research and are not specified in detail in this document.
The RADIUS accounting server MAY make requests of other servers in
order to satisfy the request, in which case it acts as a client.
If the RADIUS accounting server is unable to successfully record the
accounting packet it MUST NOT send an Accounting-Response
acknowledgment to the client.
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3. Packet Format
Exactly one RADIUS Accounting packet is encapsulated in the UDP Data
field [1], where the UDP Destination Port field indicates 1813
(decimal).
When a reply is generated, the source and destination ports are
reversed.
This memo documents the RADIUS Accounting protocol. There has been
some confusion in the assignment of port numbers for this protocol.
The early deployment of RADIUS Accounting was done using the
erroneously chosen port number 1646, which conflicts with the "sa-
msg-port" service. The officially assigned port number for RADIUS
Accounting is 1813.
A summary of the RADIUS data format is shown below. The fields are
transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Authenticator |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attributes ...
+-+-+-+-+-+-+-+-+-+-+-+-+-
Code
The Code field is one octet, and identifies the type of RADIUS
packet. When a packet is received with an invalid Code field, it is
silently discarded.
RADIUS Accounting Codes (decimal) are assigned as follows:
4 Accounting-Request
5 Accounting-Response
Identifier
The Identifier field is one octet, and aids in matching requests and
replies.
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Length
The Length field is two octets. It indicates the length of the
packet including the Code, Identifier, Length, Authenticator and
Attribute fields. Octets outside the range of the Length field
should be treated as padding and should be ignored on reception. If
the packet is shorter than the Length field indicates, it should be
silently discarded. The minimum length is 20 and maximum length is
4096.
Authenticator
The Authenticator field is sixteen (16) octets. The most significant
octet is transmitted first. This value is used to authenticate the
messages between the client and RADIUS accounting server.
Request Authenticator
In Accounting-Request Packets, the Authenticator value is a 16 octet
MD5 [3] checksum, called the Request Authenticator.
The NAS and RADIUS accounting server share a secret. The Request
Authenticator field in Accounting-Request packets contains a one- way
MD5 hash calculated over a stream of octets consisting of the Code +
Identifier + Length + 16 zero octets + request attributes + shared
secret (where + indicates concatenation). The 16 octet MD5 hash
value is stored in the Authenticator field of the Accounting-Request
packet.
Note that the Request Authenticator of an Accounting-Request can
not be done the same way as the Request Authenticator of a RADIUS
Access-Request, because there is no User-Password attribute in an
Accounting-Request.
Response Authenticator
The Authenticator field in an Accounting-Response packet is called
the Response Authenticator, and contains a one-way MD5 hash
calculated over a stream of octets consisting of the Accounting-
Response Code, Identifier, Length, the Request Authenticator field
from the Accounting-Request packet being replied to, and the response
attributes if any, followed by the shared secret. The resulting 16
octet MD5 hash value is stored in the Authenticator field of the
Accounting-Response packet.
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Attributes
Attributes may have multiple instances, in such a case the order of
attributes of the same type SHOULD be preserved. The order of
attributes of different types is not required to be preserved.
4. Packet Types
The RADIUS packet type is determined by the Code field in the first
octet of the packet.
4.1. Accounting-Request
Description
Accounting-Request packets are sent from a client (typically a
Network Access Server or its proxy) to a RADIUS accounting server,
and convey information used to provide accounting for a service
provided to a user. The client transmits a RADIUS packet with the
Code field set to 4 (Accounting-Request).
Upon receipt of an Accounting-Request, the server MUST transmit an
Accounting-Response reply if it successfully records the
accounting packet, and MUST NOT transmit any reply if it fails to
record the accounting packet.
Any attribute valid in a RADIUS Access-Request or Access-Accept
packet is valid in a RADIUS Accounting-Request packet, except that
the following attributes MUST NOT be present in an Accounting-
Request: User-Password, CHAP-Password, Reply-Message, State.
Either NAS-IP-Address or NAS-Identifier MUST be present in a
RADIUS Accounting-Request. It SHOULD contain a NAS-Port or NAS-
Port-Type attribute or both unless the service does not involve a
port or the NAS does not distinguish among its ports.
A summary of the Accounting-Request packet format is shown below.
The fields are transmitted from left to right.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Request Authenticator |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attributes ...
+-+-+-+-+-+-+-+-+-+-+-+-+-
Code
4 for Accounting-Request.
Identifier
The Identifier field MUST be changed whenever the content of the
Attributes field changes, and whenever a valid reply has been
received for a previous request. For retransmissions where the
contents are identical, the Identifier MUST remain unchanged.
Note that if Acct-Delay-Time is included in the attributes of an
Accounting-Request then the Acct-Delay-Time value will be updated
when the packet is retransmitted, changing the content of the
Attributes field and requiring a new Identifier and Request
Authenticator.
Request Authenticator
The Request Authenticator of an Accounting-Request contains a 16-
octet MD5 hash value calculated according to the method described
in "Request Authenticator" above.
Attributes
The Attributes field is variable in length, and contains a list of
Attributes.
4.2. Accounting-Response
Description
Accounting-Response packets are sent by the RADIUS accounting
server to the client to acknowledge that the Accounting-Request
has been received and recorded successfully. If the Accounting-
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Request was recorded successfully then the RADIUS accounting
server MUST transmit a packet with the Code field set to 5
(Accounting-Response). On reception of an Accounting-Response by
the client, the Identifier field is matched with a pending
Accounting-Request. Invalid packets are silently discarded.
A RADIUS Accounting-Response is not required to have any
attributes in it.
A summary of the Accounting-Response packet format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Response Authenticator |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attributes ...
+-+-+-+-+-+-+-+-+-+-+-+-+-
Code
5 for Accounting-Response.
Identifier
The Identifier field is a copy of the Identifier field of the
Accounting-Request which caused this Accounting-Response.
Response Authenticator
The Response Authenticator of an Accounting-Response contains a
16-octet MD5 hash value calculated according to the method
described in "Response Authenticator" above.
Attributes
The Attributes field is variable in length, and contains a list of
zero or more Attributes.
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5. Attributes
RADIUS Attributes carry the specific authentication, authorization
and accounting details for the request and response.
Some attributes MAY be included more than once. The effect of this
is attribute specific, and is specified in each attribute
description.
The end of the list of attributes is indicated by the Length of the
RADIUS packet.
A summary of the attribute format is shown below. The fields are
transmitted from left to right.
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
The Type field is one octet. Up-to-date values of the RADIUS Type
field are specified in the most recent "Assigned Numbers" RFC [2].
Values 192-223 are reserved for experimental use, values 224-240
are reserved for implementation-specific use, and values 241-255
are reserved and should not be used. This specification concerns
the following values:
1-39 (refer to RADIUS document [4])
40 Acct-Status-Type
41 Acct-Delay-Time
42 Acct-Input-Octets
43 Acct-Output-Octets
44 Acct-Session-Id
45 Acct-Authentic
46 Acct-Session-Time
47 Acct-Input-Packets
48 Acct-Output-Packets
49 Acct-Terminate-Cause
50 Acct-Multi-Session-Id
51 Acct-Link-Count
60+ (refer to RADIUS document [4])
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Length
The Length field is one octet, and indicates the length of this
attribute including the Type, Length and Value fields. If an
attribute is received in an Accounting-Request with an invalid
Length, the entire request should be silently discarded.
Value
The Value field is zero or more octets and contains information
specific to the attribute. The format and length of the Value
field is determined by the Type and Length fields.
The format of the value field is one of four data types.
string 0-253 octets
address 32 bit value, most significant octet first.
integer 32 bit value, most significant octet first.
time 32 bit value, most significant octet first -- seconds
since 00:00:00 GMT, January 1, 1970. The standard
Attributes do not use this data type but it is presented
here for possible use within Vendor-Specific attributes.
5.1. Acct-Status-Type
Description
This attribute indicates whether this Accounting-Request marks the
beginning of the user service (Start) or the end (Stop).
It MAY be used by the client to mark the start of accounting (for
example, upon booting) by specifying Accounting-On and to mark the
end of accounting (for example, just before a scheduled reboot) by
specifying Accounting-Off.
A summary of the Acct-Status-Type attribute format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Type
40 for Acct-Status-Type.
Length
6
Value
The Value field is four octets.
1 Start
2 Stop
7 Accounting-On
8 Accounting-Off
5.2. Acct-Delay-Time
Description
This attribute indicates how many seconds the client has been
trying to send this record for, and can be subtracted from the
time of arrival on the server to find the approximate time of the
event generating this Accounting-Request. (Network transit time
is ignored.)
Note that changing the Acct-Delay-Time causes the Identifier to
change; see the discussion under Identifier above.
A summary of the Acct-Delay-Time attribute format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
41 for Acct-Delay-Time.
Length
6
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Value
The Value field is four octets.
5.3. Acct-Input-Octets
Description
This attribute indicates how many octets have been received from
the port over the course of this service being provided, and can
only be present in Accounting-Request records where the Acct-
Status-Type is set to Stop.
A summary of the Acct-Input-Octets attribute format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
42 for Acct-Input-Octets.
Length
6
Value
The Value field is four octets.
5.4. Acct-Output-Octets
Description
This attribute indicates how many octets have been sent to the
port in the course of delivering this service, and can only be
present in Accounting-Request records where the Acct-Status-Type
is set to Stop.
A summary of the Acct-Output-Octets attribute format is shown below.
The fields are transmitted from left to right.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
43 for Acct-Output-Octets.
Length
6
Value
The Value field is four octets.
5.5. Acct-Session-Id
Description
This attribute is a unique Accounting ID to make it easy to match
start and stop records in a log file. The start and stop records
for a given session MUST have the same Acct-Session-Id. It is
strongly recommended that the Acct-Session-Id be a printable ASCII
string.
For example, one implementation uses a string with an 8-digit
upper case hexadecimal number, the first two digits increment on
each reboot (wrapping every 256 reboots) and the next 6 digits
counting from 0 for the first person logging in after a reboot up
to 2^24-1, about 16 million. Other encodings are possible.
A summary of the Acct-Session-Id attribute format is shown below.
The fields are transmitted from left to right.
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0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | String ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
44 for Acct-Session-Id.
Length
>= 3
String
The String field SHOULD be a string of printable ASCII characters.
5.6. Acct-Authentic
Description
This attribute MAY be included in an Accounting-Request to
indicate how the user was authenticated, whether by RADIUS, the
NAS itself, or another remote authentication protocol. Users who
are delivered service without being authenticated SHOULD NOT
generate Accounting records.
A summary of the Acct-Authentic attribute format is shown below. The
fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
45 for Acct-Authentic.
Length
6
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Value
The Value field is four octets.
1 RADIUS
2 Local
3 Remote
5.7. Acct-Session-Time
Description
This attribute indicates how many seconds the user has received
service for, and can only be present in Accounting-Request records
where the Acct-Status-Type is set to Stop.
A summary of the Acct-Session-Time attribute format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
46 for Acct-Session-Time.
Length
6
Value
The Value field is four octets.
5.8. Acct-Input-Packets
Description
This attribute indicates how many packets have been received from
the port over the course of this service being provided to a
Framed User, and can only be present in Accounting-Request records
where the Acct-Status-Type is set to Stop.
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A summary of the Acct-Input-packets attribute format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
47 for Acct-Input-Packets.
Length
6
Value
The Value field is four octets.
5.9. Acct-Output-Packets
Description
This attribute indicates how many packets have been sent to the
port in the course of delivering this service to a Framed User,
and can only be present in Accounting-Request records where the
Acct-Status-Type is set to Stop.
A summary of the Acct-Output-Packets attribute format is shown below.
The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
48 for Acct-Output-Packets.
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Length
6
Value
The Value field is four octets.
5.10. Acct-Terminate-Cause
Description
This attribute indicates how the session was terminated, and can
only be present in Accounting-Request records where the Acct-
Status-Type is set to Stop.
A summary of the Acct-Terminate-Cause attribute format is shown
below. The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
49 for Acct-Terminate-Cause
Length
6
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Value
The Value field is four octets, containing an integer specifying
the cause of session termination, as follows:
1 User Request
2 Lost Carrier
3 Lost Service
4 Idle Timeout
5 Session Timeout
6 Admin Reset
7 Admin Reboot
8 Port Error
9 NAS Error
10 NAS Request
11 NAS Reboot
12 Port Unneeded
13 Port Preempted
14 Port Suspended
15 Service Unavailable
16 Callback
17 User Error
18 Host Request
The termination causes are as follows:
User Request User requested termination of service, for
example with LCP Terminate or by logging out.
Lost Carrier DCD was dropped on the port.
Lost Service Service can no longer be provided; for
example, user's connection to a host was
interrupted.
Idle Timeout Idle timer expired.
Session Timeout Maximum session length timer expired.
Admin Reset Administrator reset the port or session.
Admin Reboot Administrator is ending service on the NAS,
for example prior to rebooting the NAS.
Port Error NAS detected an error on the port which
required ending the session.
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NAS Error NAS detected some error (other than on the
port) which required ending the session.
NAS Request NAS ended session for a non-error reason not
otherwise listed here.
NAS Reboot The NAS ended the session in order to reboot
non-administratively ("crash").
Port Unneeded NAS ended session because resource usage fell
below low-water mark (for example, if a
bandwidth-on-demand algorithm decided that
the port was no longer needed).
Port Preempted NAS ended session in order to allocate the
port to a higher priority use.
Port Suspended NAS ended session to suspend a virtual
session.
Service Unavailable NAS was unable to provide requested service.
Callback NAS is terminating current session in order
to perform callback for a new session.
User Error Input from user is in error, causing
termination of session.
Host Request Login Host terminated session normally.
5.11. Acct-Multi-Session-Id
Description
This attribute is a unique Accounting ID to make it easy to link
together multiple related sessions in a log file. Each session
linked together would have a unique Acct-Session-Id but the same
Acct-Multi-Session-Id. It is strongly recommended that the Acct-
Multi-Session-Id be a printable ASCII string.
A summary of the Acct-Session-Id attribute format is shown below.
The fields are transmitted from left to right.
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | String ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Type
50 for Acct-Multi-Session-Id.
Length
>= 3
String
The String field SHOULD be a string of printable ASCII characters.
5.12. Acct-Link-Count
Description
This attribute gives the count of links which are known to have
been in a given multilink session at the time the accounting
record is generated. The NAS MAY include the Acct-Link-Count
attribute in any Accounting-Request which might have multiple
links.
A summary of the Acct-Link-Count attribute format is show below. The
fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
51 for Acct-Link-Count.
Length
6
Value
The Value field is four octets, and contains the number of links
seen so far in this Multilink Session.
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It may be used to make it easier for an accounting server to know
when it has all the records for a given Multilink session. When
the number of Accounting-Requests received with Acct-Status-Type =
Stop and the same Acct-Multi-Session-Id and unique Acct-Session-
Id's equals the largest value of Acct-Link-Count seen in those
Accounting-Requests, all Stop Accounting-Requests for that
Multilink Session have been received.
An example showing 8 Accounting-Requests should make things
clearer. For clarity only the relevant attributes are shown, but
additional attributes containing accounting information will also
be present in the Accounting-Request.
Multi-Session-Id Session-Id Status-Type Link-Count
"10" "10" Start 1
"10" "11" Start 2
"10" "11" Stop 2
"10" "12" Start 3
"10" "13" Start 4
"10" "12" Stop 4
"10" "13" Stop 4
"10" "10" Stop 4
5.13. Table of Attributes
The following table provides a guide to which attributes may be found
in Accounting-Request packets. No attributes should be found in
Accounting-Response packets except Proxy-State and possibly Vendor-
Specific.
# Attribute
0-1 User-Name
0 User-Password
0 CHAP-Password
0-1 NAS-IP-Address [5]
0-1 NAS-Port
0-1 Service-Type
0-1 Framed-Protocol
0-1 Framed-IP-Address
0-1 Framed-IP-Netmask
0-1 Framed-Routing
0+ Filter-Id
0-1 Framed-MTU
0+ Framed-Compression
0+ Login-IP-Host
0-1 Login-Service
0-1 Login-TCP-Port
0 Reply-Message
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0-1 Callback-Number
0-1 Callback-Id
0+ Framed-Route
0-1 Framed-IPX-Network
0 State
0+ Class
0+ Vendor-Specific
0-1 Session-Timeout
0-1 Idle-Timeout
0-1 Termination-Action
0-1 Called-Station-Id
0-1 Calling-Station-Id
0-1 NAS-Identifier [4]
0+ Proxy-State
0-1 Login-LAT-Service
0-1 Login-LAT-Node
0-1 Login-LAT-Group
0-1 Framed-AppleTalk-Link
0-1 Framed-AppleTalk-Network
0-1 Framed-AppleTalk-Zone
1 Acct-Status-Type
0-1 Acct-Delay-Time
0-1 Acct-Input-Octets
0-1 Acct-Output-Octets
1 Acct-Session-Id
0-1 Acct-Authentic
0-1 Acct-Session-Time
0-1 Acct-Input-Packets
0-1 Acct-Output-Packets
0-1 Acct-Terminate-Cause
0+ Acct-Multi-Session-Id
0+ Acct-Link-Count
0 CHAP-Challenge
0-1 NAS-Port-Type
0-1 Port-Limit
0-1 Login-LAT-Port
[5] An Accounting-Request MUST contain either a NAS-IP-Address or a
NAS-Identifier, and it is permitted (but not recommended) for it to
contain both.
The following table defines the above table entries.
0 This attribute MUST NOT be present
0+ Zero or more instances of this attribute MAY be present.
0-1 Zero or one instance of this attribute MAY be present.
1 Exactly one instance of this attribute MUST be present.
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Security Considerations
Security issues are briefly discussed in sections concerning the
authenticator included in accounting requests and responses, using a
shared secret which is never sent over the network.
References
[1] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
USC/Information Sciences Institute, August 1980.
[2] Reynolds, J., and Postel, J., "Assigned Numbers", STD 2, RFC
1700, USC/Information Sciences Institute, October 1994.
[3] Rivest, R., and Dusse, S., "The MD5 Message-Digest Algorithm",
RFC 1321, MIT Laboratory for Computer Science, RSA Data
Security Inc., April 1992.
[4] Rigney, C., Rubens, A., Simpson, W., and Willens, S., "Remote
Authentication Dial In User Service (RADIUS)", RFC 2138,
April 1997.
Acknowledgments
RADIUS and RADIUS Accounting were originally developed by Livingston
Enterprises for their PortMaster series of Network Access Servers.
Chair's Address
The RADIUS working group can be contacted via the current chair:
Carl Rigney
Livingston Enterprises
4464 Willow Road
Pleasanton, California 94588
Phone: +1 510 426 0770
EMail: cdr@livingston.com
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Author's Address
Questions about this memo can also be directed to:
Carl Rigney
Livingston Enterprises
4464 Willow Road
Pleasanton, California 94588
EMail: cdr@livingston.com
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