Network Working Group B. Aboba
Request for Comments: 2618 G. Zorn
Category: Standards Track Microsoft
June 1999

RADIUS Authentication Client MIB

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1999). All Rights Reserved.

Abstract

This memo defines a set of extensions which instrument RADIUS
authentication client functions. These extensions represent a portion
of the Management Information Base (MIB) for use with network
management protocols in the Internet community. Using these
extensions IP-based management stations can manage RADIUS
authentication clients.

1. IntrodUCtion

This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
In particular, it describes managed objects used for managing RADIUS
authentication clients.

Today a wide range of network devices, including routers and NASes,
act as RADIUS authentication clients in order to provide
authentication and authorization services. As a result, the effective
management of RADIUS authentication clients is of considerable
importance.

2. The SNMP Management Framework

The SNMP Management Framework presently consists of five major
components:

o An overall architecture, described in RFC2571 [1].

o Mechanisms for describing and naming objects and events for the
purpose of management. The first version of this Structure of
Management Information (SMI) is called SMIv1 and described in
STD 16, RFC1155 [2], STD 16, RFC1212 [3] and RFC1215 [4].
The second version, called SMIv2, is described in STD 58, RFC
2578 [5], RFC2579 [6] and RFC2580 [7].

o Message protocols for transferring management information. The
first version of the SNMP message protocol is called SNMPv1 and
described in STD 15, RFC1157 [8]. A second version of the
SNMP message protocol, which is not an Internet standards
track protocol, is called SNMPv2c and described in RFC1901
[9] and RFC1906 [10]. The third version of the message
protocol is called SNMPv3 and described in RFC1906 [10], RFC
2572 [11] and RFC2574 [12].

o Protocol operations for Accessing management information. The
first set of protocol operations and associated PDU formats is
described in STD 15, RFC1157 [8]. A second set of protocol
operations and associated PDU formats is described in RFC1905
[13].

o A set of fundamental applications described in RFC2573 [14] and
the view-based access control mechanism described in RFC2575
[15].

Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the mechanisms defined in the SMI.

This memo specifies a MIB module that is compliant to the SMIv2. A
MIB conforming to the SMIv1 can be produced through the appropriate
translations. The resulting translated MIB must be semantically
equivalent, except where objects or events are omitted because no
translation is possible (use of Counter64). Some machine readable
information in SMIv2 will be converted into textual descriptions in
SMIv1 during the translation process. However, this loss of machine
readable information is not considered to change the semantics of the
MIB.

3. Overview

The RADIUS authentication protocol, described in [16], distinguishes
between the client function and the server function. In RADIUS
authentication, clients send Access-Requests, and servers reply with
Access-Accepts, Access-Rejects, and Access-Challenges. Typically NAS
devices implement the client function, and thus would be eXPected to
implement the RADIUS authentication client MIB, while RADIUS
authentication servers implement the server function, and thus would
be expected to implement the RADIUS authentication server MIB.

However, it is possible for a RADIUS authentication entity to perform
both client and server functions. For example, a RADIUS proxy may act
as a server to one or more RADIUS authentication clients, while
simultaneously acting as an authentication client to one or more
authentication servers. In such situations, it is expected that
RADIUS entities combining client and server functionality will
support both the client and server MIBs.

3.1. Selected objects

This MIB module contains two scalars as well as a single table:

(1) the RADIUS Authentication Server Table contains one row for
each RADIUS authentication server that the client shares a
secret with.

Each entry in the RADIUS Authentication Server Table includes fifteen
columns presenting a view of the activity of the RADIUS
authentication client.

4. Definitions

RADIUS-AUTH-CLIENT-MIB DEFINITIONS ::= BEGIN

IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, OBJECT-IDENTITY,
Counter32, Integer32, Gauge32,
IpAddress, TimeTicks, mib-2 FROM SNMPv2-SMI
SnmpAdminString FROM SNMP-FRAMEWORK-MIB
MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF;

radiusAuthClientMIB MODULE-IDENTITY
LAST-UPDATED "9906110000Z" -- 11 Jun 1999
ORGANIZATION "IETF RADIUS Working Group."
CONTACT-INFO
" Bernard Aboba
Microsoft

One Microsoft Way
Redmond, WA 98052
US

Phone: +1 425 936 6605
EMail: bernarda@microsoft.com"
DESCRIPTION
"The MIB module for entities implementing the client
side of the Remote Access Dialin User Service (RADIUS)
authentication protocol."
REVISION "9906110000Z" -- 11 Jun 1999
DESCRIPTION "Initial version as published in RFC2618"
::= { radiusAuthentication 2 }

radiusMIB OBJECT-IDENTITY
STATUS current
DESCRIPTION
"The OID assigned to RADIUS MIB work by the IANA."
::= { mib-2 67 }

radiusAuthentication OBJECT IDENTIFIER ::= {radiusMIB 1}

radiusAuthClientMIBObjects OBJECT IDENTIFIER ::=
{ radiusAuthClientMIB 1 }

radiusAuthClient OBJECT IDENTIFIER ::= { radiusAuthClientMIBObjects 1 }

radiusAuthClientInvalidServerAddresses OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Response packets
received from unknown addresses."
::= { radiusAuthClient 1 }

radiusAuthClientIdentifier OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The NAS-Identifier of the RADIUS authentication client.
This is not necessarily the same as sysName in MIB II."
::= { radiusAuthClient 2 }

radiusAuthServerTable OBJECT-TYPE
SYNTAX SEQUENCE OF RadiusAuthServerEntry
MAX-ACCESS not-accessible

STATUS current
DESCRIPTION
"The (conceptual) table listing the RADIUS authentication
servers with which the client shares a secret."
::= { radiusAuthClient 3 }

radiusAuthServerEntry OBJECT-TYPE
SYNTAX RadiusAuthServerEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry (conceptual row) representing a RADIUS
authentication server with which the client shares
a secret."
INDEX { radiusAuthServerIndex }
::= { radiusAuthServerTable 1 }

RadiusAuthServerEntry ::= SEQUENCE {
radiusAuthServerIndex Integer32,
radiusAuthServerAddress IpAddress,
radiusAuthClientServerPortNumber Integer32,
radiusAuthClientRoundTripTime TimeTicks,
radiusAuthClientAccessRequests Counter32,
radiusAuthClientAccessRetransmissions Counter32,
radiusAuthClientAccessAccepts Counter32,
radiusAuthClientAccessRejects Counter32,
radiusAuthClientAccessChallenges Counter32,
radiusAuthClientMalformedAccessResponses Counter32,
radiusAuthClientBadAuthenticators Counter32,
radiusAuthClientPendingRequests Gauge32,
radiusAuthClientTimeouts Counter32,
radiusAuthClientUnknownTypes Counter32,
radiusAuthClientPacketsDropped Counter32
}

radiusAuthServerIndex OBJECT-TYPE
SYNTAX Integer32 (1..2147483647)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A number uniquely identifying each RADIUS
Authentication server with which this client
communicates."
::= { radiusAuthServerEntry 1 }

radiusAuthServerAddress OBJECT-TYPE
SYNTAX IpAddress
MAX-ACCESS read-only

STATUS current
DESCRIPTION
"The IP address of the RADIUS authentication server
referred to in this table entry."
::= { radiusAuthServerEntry 2 }

radiusAuthClientServerPortNumber OBJECT-TYPE
SYNTAX Integer32 (0..65535)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The UDP port the client is using to send requests to
this server."
::= { radiusAuthServerEntry 3 }

radiusAuthClientRoundTripTime OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The time interval (in hundredths of a second) between
the most recent Access-Reply/Access-Challenge and the
Access-Request that matched it from this RADIUS
authentication server."
::= { radiusAuthServerEntry 4 }

-- Request/Response statistics
--
-- TotalIncomingPackets = Accepts + Rejects + Challenges + UnknownTypes
--
-- TotalIncomingPackets - MalformedResponses - BadAuthenticators -
-- UnknownTypes - PacketsDropped = Successfully received
--
-- AccessRequests + PendingRequests + ClientTimeouts =
-- Successfully Received
--
--

radiusAuthClientAccessRequests OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Request packets sent
to this server. This does not include retransmissions."
::= { radiusAuthServerEntry 5 }

radiusAuthClientAccessRetransmissions OBJECT-TYPE

SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Request packets
retransmitted to this RADIUS authentication server."
::= { radiusAuthServerEntry 6 }

radiusAuthClientAccessAccepts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Accept packets
(valid or invalid) received from this server."
::= { radiusAuthServerEntry 7 }

radiusAuthClientAccessRejects OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Reject packets
(valid or invalid) received from this server."
::= { radiusAuthServerEntry 8 }

radiusAuthClientAccessChallenges OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Challenge packets
(valid or invalid) received from this server."
::= { radiusAuthServerEntry 9 }

-- "Access-Response" includes an Access-Accept, Access-Challenge
-- or Access-Reject

radiusAuthClientMalformedAccessResponses OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of malformed RADIUS Access-Response
packets received from this server.
Malformed packets include packets with
an invalid length. Bad authenticators or
Signature attributes or unknown types are not

included as malformed access responses."
::= { radiusAuthServerEntry 10 }

radiusAuthClientBadAuthenticators OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Response packets
containing invalid authenticators or Signature
attributes received from this server."
::= { radiusAuthServerEntry 11 }

radiusAuthClientPendingRequests OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS Access-Request packets
destined for this server that have not yet timed out
or received a response. This variable is incremented
when an Access-Request is sent and decremented due to
receipt of an Acess-Accept, Access-Reject or
Access-Challenge, a timeout or retransmission."
::= { radiusAuthServerEntry 12 }

radiusAuthClientTimeouts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of authentication timeouts to this server.
After a timeout the client may retry to the same
server, send to a different server, or
give up. A retry to the same server is counted as a
retransmit as well as a timeout. A send to a different
server is counted as a Request as well as a timeout."
::= { radiusAuthServerEntry 13 }

radiusAuthClientUnknownTypes OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS packets of unknown type which
were received from this server on the authentication port."
::= { radiusAuthServerEntry 14 }

radiusAuthClientPacketsDropped OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of RADIUS packets of which were
received from this server on the authentication port
and dropped for some other reason."
::= { radiusAuthServerEntry 15 }

-- conformance information

radiusAuthClientMIBConformance
OBJECT IDENTIFIER ::= { radiusAuthClientMIB 2 }
radiusAuthClientMIBCompliances
OBJECT IDENTIFIER ::= { radiusAuthClientMIBConformance 1 }
radiusAuthClientMIBGroups
OBJECT IDENTIFIER ::= { radiusAuthClientMIBConformance 2 }

-- compliance statements

radiusAuthClientMIBCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for authentication clients
implementing the RADIUS Authentication Client MIB."
MODULE -- this module
MANDATORY-GROUPS { radiusAuthClientMIBGroup }

::= { radiusAuthClientMIBCompliances 1 }

-- units of conformance

radiusAuthClientMIBGroup OBJECT-GROUP
OBJECTS { radiusAuthClientIdentifier,
radiusAuthClientInvalidServerAddresses,
radiusAuthServerAddress,
radiusAuthClientServerPortNumber,
radiusAuthClientRoundTripTime,
radiusAuthClientAccessRequests,
radiusAuthClientAccessRetransmissions,
radiusAuthClientAccessAccepts,
radiusAuthClientAccessRejects,
radiusAuthClientAccessChallenges,
radiusAuthClientMalformedAccessResponses,

radiusAuthClientBadAuthenticators,
radiusAuthClientPendingRequests,
radiusAuthClientTimeouts,
radiusAuthClientUnknownTypes,
radiusAuthClientPacketsDropped
}
STATUS current
DESCRIPTION
"The basic collection of objects providing management of
RADIUS Authentication Clients."
::= { radiusAuthClientMIBGroups 1 }

END

5. References

[1] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for
Describing SNMP Management Frameworks", RFC2571, April 1999.

[2] Rose, M., and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based Internets", STD 16, RFC
1155, May 1990.

[3] Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD 16,
RFC1212, March 1991.

[4] Rose, M., "A Convention for Defining Traps for use with the
SNMP", RFC1215, Performance Systems International, March 1991.

[5] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC2578, April 1999.

[6] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58,
RFC2579, April 1999.

[7] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Conformance Statements for SMIv2", STD
58, RFC2580, April 1999.

[8] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
Network Management Protocol", STD 15, RFC1157, May 1990.

[9] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
"Introduction to Community-based SNMPv2", RFC1901, January
1996.

[10] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser,
"Transport Mappings for Version 2 of the Simple Network
Management Protocol (SNMPv2)", RFC1906, January 1996.

[11] Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message
Processing and Dispatching for the Simple Network Management
Protocol (SNMP)", RFC2572, April 1999.

[12] Blumenthal, U., and B. Wijnen, "User-based Security Model for
Version 3 of the Simple Network Management Protocol (SNMPv3)",
RFC2574, April 1999.

[13] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol
Operations for Version 2 of the Simple Network Management
Protocol (SNMPv2)", RFC1905, January 1996.

[14] Levi, D., Meyer, P., and B. Stewart, "SNMP Applications", RFC
2573, April 1999.

[15] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access
Control Model for the Simple Network Management Protocol
(SNMP)", RFC2575, April 1999.

[16] Rigney, C., Rubens, A., Simpson W. and S. Willens, "Remote
Authentication Dial In User Service (RADIUS)", RFC2138, April
1997.

6. Security Considerations

There are no management objects defined in this MIB that have a MAX-
ACCESS clause of read-write and/or read-create. So, if this MIB is
implemented correctly, then there is no risk that an intruder can
alter or create any management objects of this MIB via direct SNMP
SET operations.

There are a number of managed objects in this MIB that may contain
sensitive information. These are:

radiusAuthServerAddress
This can be used to determine the address of the RADIUS
authentication server with which the client is
communicating. This information could be useful in
mounting an attack on the authentication server.

radiusAuthClientServerPortNumber This can be used to determine the
port number on which the RADIUS authentication client is
sending. This information could be useful in impersonating
the client in order to send data to the authentication

server.

It is thus important to control even GET access to these objects and
possibly to even encrypt the values of these object when sending them
over the network via SNMP. Not all versions of SNMP provide features
for such a secure environment.

SNMPv1 by itself is not a secure environment. Even if the network
itself is secure (for example by using IPSec), there is no control as
to who on the secure network is allowed to access and GET/SET
(read/change/create/delete) the objects in this MIB.

It is recommended that the implementers consider the security
features as provided by the SNMPv3 framework. Specifically, the use
of the User-based Security Model RFC2574 [12] and the View-based
Access Control Model RFC2575 [15] is recommended. Using these
security features, customer/users can give access to the objects only
to those principals (users) that have legitimate rights to GET or SET
(change/create/delete) them.

7. Acknowledgments

The authors acknowledge the contributions of the RADIUS Working Group
in the development of this MIB. Thanks to Narendra Gidwani of
Microsoft, Allan C. Rubens of MERIT, Carl Rigney of Livingston and
Peter Heitman of American Internet Corporation for useful discussions
of this problem space.

8. Authors' Addresses

Bernard Aboba
Microsoft Corporation
One Microsoft Wy
Redmond, WA 98052

Phone: 425-936-6605
EMail: bernarda@microsoft.com

Glen Zorn
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052

Phone: 425-703-1559
EMail: glennz@microsoft.com

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