Network Working Group L. Heintz Request For Comments: 2742 Cisco Systems Category: Standards Track S. Gudur Independent Consultant M. Ellison, Ed. Ellison Software Consulting, Inc. January 2000
Definitions of Managed Objects for Extensible SNMP Agents
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 (2000). All Rights Reserved.
Abstract
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 objects managing SNMP agents that use the Agent Extensibility (AgentX) Protocol.
This memo specifies a MIB module in a manner that is both compliant to the SMIv2, and semantically identical to the peer SMIv1 definitions.
The SNMP Management Framework presently consists of five major components:
- An overall architecture, described in RFC 2571 [1].
- 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, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The second version, called SMIv2, is described in STD 58, RFC 2578 [5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7].
- Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in STD 15, RFC 1157 [8]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12].
- Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15, RFC 1157 [8]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [13].
- A set of fundamental applications described in RFC 2573 [14] and the view-based access control mechanism described in RFC 2575 [15].
A more detailed introduction to the current SNMP Management Framework can be found in RFC 2570 [16].
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
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SMIv1 during the translation process. However, this loss of machine readable information is not considered to change the semantics of the MIB.
The SNMP Agent Extensibility Protocol (AgentX) is a protocol used to distribute the implementation of an SNMP agent amongst a single "master agent" and multiple "subagents". See [17] for details about the AgentX protocol.
The goals of the AgentX MIB are:
- List the set of subagent connections that currently have logical sessions open with the master agent.
- Identify each subagent connection transport address and type.
- Identify each subagent session vendor, AgentX protocol version, and other characteristics.
- Identify the set of MIB objects each session implements, the context in which the objects are registered, and the priority of the registration.
- Determine protocol operational parameters such as the timeout interval for responses from a session and the priority at which a session registers a particular MIB region.
- Allow (but do not require) managers to explicitly close subagent sessions with the master agent.
This MIB is organized into four groups. The agentxGeneral group provides information describing the master agent's AgentX support, including the protocol version supported. The agentxConnection group provides information describing the current set of connections capable of carrying AgentX sessions. The agentxSession group provides information describing the current set of AgentX sessions. The agentxRegistration group provides information describing the current set of registrations.
Three tables form the heart of this mib. These are the connection, session, and registration tables.
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Entries in the registration table exist in a many-to-one relationship with entries in the session table. This relationship is expressed through the two common indices, agentxSessionIndex and agentxConnIndex. Entries in the registration table also exist in a many-to-one relationship with entries in the connection table. This relationship is expressed through the common index, agentxConnIndex.
Entries in the session table exist in a many-to-one relationship with entries in the connection table. This relationship is expressed through the common index, agentxConnIndex.
" DESCRIPTION "This is the MIB module for the SNMP Agent Extensibility Protocol (AgentX). This MIB module will be implemented by the master agent. "
REVISION "200001100000Z" -- Midnight 10 January 2000 DESCRIPTION "Initial version published as RFC 2742."
::= { mib-2 74 }
-- Textual Conventions
AgentxTAddress ::= TEXTUAL-CONVENTION STATUS current DESCRIPTION "Denotes a transport service address. This is identical to the TAddress textual convention (SNMPv2-SMI) except that zero-length values are permitted. " SYNTAX OCTET STRING (SIZE (0..255))
agentxDefaultTimeout OBJECT-TYPE SYNTAX INTEGER (0..255) UNITS "seconds" MAX-ACCESS read-only STATUS current DESCRIPTION "The default length of time, in seconds, that the master agent should allow to elapse after dispatching a message to a session before it regards the subagent as not responding. This is a system-wide value that may override the timeout value associated with a particular session (agentxSessionTimeout) or a particular registered MIB region (agentxRegTimeout). If the associated value of agentxSessionTimeout and agentxRegTimeout are zero, or impractical in accordance with implementation-specific procedure of the master agent, the value represented by this object will be the effective timeout value for the
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master agent to await a response to a dispatch from a given subagent. " DEFVAL { 5 } ::= { agentxGeneral 1 }
agentxMasterAgentXVer OBJECT-TYPE SYNTAX INTEGER (1..255) MAX-ACCESS read-only STATUS current DESCRIPTION "The AgentX protocol version supported by this master agent. The current protocol version is 1. Note that the master agent must also allow interaction with earlier version subagents. " ::= { agentxGeneral 2 }
-- The AgentX Subagent Connection Group
agentxConnTableLastChange OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime when the last row creation or deletion occurred in the agentxConnectionTable. " ::= { agentxConnection 1 }
agentxConnectionTable OBJECT-TYPE SYNTAX SEQUENCE OF AgentxConnectionEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "The agentxConnectionTable tracks all current AgentX transport connections. There may be zero, one, or more AgentX sessions carried on a given AgentX connection. " ::= { agentxConnection 2 }
agentxConnectionEntry OBJECT-TYPE SYNTAX AgentxConnectionEntry MAX-ACCESS not-accessible STATUS current
DESCRIPTION "An agentxConnectionEntry contains information describing a single AgentX transport connection. A connection may be
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used to support zero or more AgentX sessions. An entry is created when a new transport connection is established, and is destroyed when the transport connection is terminated. " INDEX { agentxConnIndex } ::= { agentxConnectionTable 1 }
agentxConnIndex OBJECT-TYPE SYNTAX Unsigned32 (1..4294967295) MAX-ACCESS not-accessible STATUS current DESCRIPTION "agentxConnIndex contains the value that uniquely identifies an open transport connection used by this master agent to provide AgentX service. Values of this index should not be re-used. The value assigned to a given transport connection is constant for the lifetime of that connection. " ::= { agentxConnectionEntry 1 }
agentxConnOpenTime OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime when this connection was established and, therefore, its value when this entry was added to the table. " ::= { agentxConnectionEntry 2 }
agentxConnTransportDomain OBJECT-TYPE SYNTAX TDomain MAX-ACCESS read-only STATUS current DESCRIPTION "The transport protocol in use for this connection to the subagent. " ::= { agentxConnectionEntry 3 }
MAX-ACCESS read-only STATUS current DESCRIPTION "The transport address of the remote (subagent) end of this connection to the master agent. This object may be zero-length for unix-domain sockets (and possibly other types of transport addresses) since the subagent need not bind a filename to its local socket. " ::= { agentxConnectionEntry 4 }
-- The AgentX Subagent Session Group
agentxSessionTableLastChange OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime when the last row creation or deletion occurred in the agentxSessionTable. " ::= { agentxSession 1 }
agentxSessionTable OBJECT-TYPE SYNTAX SEQUENCE OF AgentxSessionEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of AgentX subagent sessions currently in effect. " ::= { agentxSession 2 }
agentxSessionEntry OBJECT-TYPE SYNTAX AgentxSessionEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Information about a single open session between the AgentX master agent and a subagent is contained in this entry. An entry is created when a new session is successfully established and is destroyed either when the subagent transport connection has terminated or when the subagent session is closed. " INDEX { agentxConnIndex, agentxSessionIndex } ::= { agentxSessionTable 1 }
agentxSessionIndex OBJECT-TYPE SYNTAX Unsigned32 (0..4294967295) MAX-ACCESS not-accessible STATUS current DESCRIPTION "A unique index for the subagent session. It is the same as h.sessionID defined in the agentx header. Note that if a subagent's session with the master agent is closed for any reason its index should not be re-used. A value of zero(0) is specifically allowed in order to be compatible with the definition of h.sessionId. " ::= { agentxSessionEntry 1 }
agentxSessionObjectID OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-only STATUS current DESCRIPTION "This is taken from the o.id field of the agentx-Open-PDU. This attribute will report a value of '0.0' for subagents not supporting the notion of an AgentX session object identifier. " ::= { agentxSessionEntry 2 }
agentxSessionDescr OBJECT-TYPE SYNTAX SnmpAdminString MAX-ACCESS read-only STATUS current DESCRIPTION "A textual description of the session. This is analogous to sysDescr defined in the SNMPv2-MIB in RFC 1907 [19] and is taken from the o.descr field of the agentx-Open-PDU. This attribute will report a zero-length string value for subagents not supporting the notion of a session description. " ::= { agentxSessionEntry 3 }
agentxSessionAdminStatus OBJECT-TYPE
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SYNTAX INTEGER { up(1), down(2) } MAX-ACCESS read-write STATUS current DESCRIPTION "The administrative (desired) status of the session. Setting the value to 'down(2)' closes the subagent session (with c.reason set to 'reasonByManager'). " ::= { agentxSessionEntry 4 }
agentxSessionOpenTime OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime when this session was opened and, therefore, its value when this entry was added to the table. " ::= { agentxSessionEntry 5 }
agentxSessionAgentXVer OBJECT-TYPE SYNTAX INTEGER (1..255) MAX-ACCESS read-only STATUS current DESCRIPTION "The version of the AgentX protocol supported by the session. This must be less than or equal to the value of agentxMasterAgentXVer. " ::= { agentxSessionEntry 6 }
agentxSessionTimeout OBJECT-TYPE SYNTAX INTEGER (0..255) UNITS "seconds" MAX-ACCESS read-only STATUS current DESCRIPTION "The length of time, in seconds, that a master agent should allow to elapse after dispatching a message to this session before it regards the subagent as not responding. This value is taken from the o.timeout field of the agentx-Open-PDU. This is a session-specific value that may be overridden by values associated with the specific registered MIB regions (see agentxRegTimeout). A value of zero(0) indicates that the master agent's default timeout value should be used
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(see agentxDefaultTimeout). " ::= { agentxSessionEntry 7 }
-- The AgentX Registration Group
agentxRegistrationTableLastChange OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime when the last row creation or deletion occurred in the agentxRegistrationTable. " ::= { agentxRegistration 1 }
agentxRegistrationTable OBJECT-TYPE SYNTAX SEQUENCE OF AgentxRegistrationEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of registered regions. " ::= { agentxRegistration 2 }
agentxRegistrationEntry OBJECT-TYPE SYNTAX AgentxRegistrationEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Contains information for a single registered region. An entry is created when a session successfully registers a region and is destroyed for any of three reasons: this region is unregistered by the session, the session is closed, or the subagent connection is closed. " INDEX { agentxConnIndex, agentxSessionIndex, agentxRegIndex } ::= { agentxRegistrationTable 1 }
agentxRegIndex OBJECT-TYPE SYNTAX Unsigned32 (1..4294967295) MAX-ACCESS not-accessible STATUS current DESCRIPTION "agentxRegIndex uniquely identifies a registration entry. This value is constant for the lifetime of an entry. " ::= { agentxRegistrationEntry 1 }
agentxRegContext OBJECT-TYPE SYNTAX OCTET STRING MAX-ACCESS read-only STATUS current DESCRIPTION "The context in which the session supports the objects in this region. A zero-length context indicates the default context. " ::= { agentxRegistrationEntry 2 }
agentxRegStart OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-only STATUS current DESCRIPTION "The starting OBJECT IDENTIFIER of this registration entry. The session identified by agentxSessionIndex implements objects starting at this value (inclusive). Note that this value could identify an object type, an object instance, or a partial object instance. " ::= { agentxRegistrationEntry 3 }
agentxRegRangeSubId OBJECT-TYPE SYNTAX Unsigned32 MAX-ACCESS read-only STATUS current DESCRIPTION "agentxRegRangeSubId is used to specify the range. This is taken from r.region_subid in the registration PDU. If the value of this object is zero, no range is specified. If it is non-zero, it identifies the `nth' sub-identifier in r.region for which this entry's agentxRegUpperBound value is substituted in the OID for purposes of defining the region's upper bound. " ::= { agentxRegistrationEntry 4 }
agentxRegUpperBound OBJECT-TYPE
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SYNTAX Unsigned32 MAX-ACCESS read-only STATUS current DESCRIPTION "agentxRegUpperBound represents the upper-bound sub-identifier in a registration. This is taken from the r.upper_bound in the registration PDU. If agentxRegRangeSubid (r.region_subid) is zero, this value is also zero and is not used to define an upper bound for this registration. " ::= { agentxRegistrationEntry 5 }
agentxRegPriority OBJECT-TYPE SYNTAX Unsigned32 MAX-ACCESS read-only STATUS current DESCRIPTION "The registration priority. Lower values have higher priority. This value is taken from r.priority in the register PDU. Sessions should use the value of 127 for r.priority if a default value is desired. " ::= { agentxRegistrationEntry 6 }
agentxRegTimeout OBJECT-TYPE SYNTAX INTEGER (0..255) UNITS "seconds" MAX-ACCESS read-only STATUS current DESCRIPTION "The timeout value, in seconds, for responses to requests associated with this registered MIB region. A value of zero(0) indicates the default value (indicated by by agentxSessionTimeout or agentxDefaultTimeout) is to be used. This value is taken from the r.timeout field of the agentx-Register-PDU. " ::= { agentxRegistrationEntry 7 }
agentxRegInstance OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-only STATUS current DESCRIPTION "The value of agentxRegInstance is `true' for registrations for which the INSTANCE_REGISTRATION was set, and is `false' for all other registrations. "
agentxMIBCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement for SNMP entities that implement the AgentX protocol. Note that a compliant agent can implement all objects in this MIB module as read-only. " MODULE -- this module MANDATORY-GROUPS { agentxMIBGroup }
OBJECT agentxSessionAdminStatus MIN-ACCESS read-only DESCRIPTION "Write access is not required. " ::= { agentxMIBCompliances 1 }
The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director.
This document is the result of the efforts of the IETF AgentX Working Group (WG).
This MIB is an evolution of the Subagent MIB by Bert Wijnen (wijnen@vnet.ibm.com) which in turn was derived from the SMUX-MIB by Marshall Rose [18].
Thanks are in order to the following AgentX WG members:
Mike Daniele (Compaq Computer Corporation) Dale Francisco (Cisco Systems) Bob Natale (ACE*COMM Corporation) Randy Presuhn (BMC Software, Inc.) Shawn Routhier (Epilogue) Mike Thatcher (Independent Consultant)
Special acknowledgement is made to:
Maria Greene (Xedia)
Special acknowledgement is also made to the following individuals for participating in the 1998 AgentX testing summit (bakeoff) held in Sunnyvale, California:
Jeff Case (SNMP Research, Inc.) Mike Daniele (Compaq Computer Corporation) Mark Ellison (Ellison Software Consulting, Inc.) Lauren Heintz (BMC Software, Inc.) Verne Hyde (Independent Consultant) Bob Natale (ACE*COMM Corporation) Shawn Routhier (Epilogue) Mike Thatcher (Independent Consultant) Bert Wijnen (IBM T. J. Watson Research Center)
There is a single management object defined in this MIB that has a MAX-ACCESS clause of read-write. This object may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations.
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There is a single managed object in this MIB that may contain sensitive information. This object is agentxSessionAdminStatus. Setting agentxSessionAdminStatus to an inappropriate value can effectively prevent access to management information, or provide access to inappropriate information.
It is thus important to control even GET access to these objects and possibly to even encrypt the values of these objects 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), even then, 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 RFC 2574 [12] and the View-based Access Control Model RFC 2575 [15] is recommended.
It is then a customer/user responsibility to ensure that the SNMP entity giving access to an instance of this MIB, is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/delete) them.
[1] Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for Describing SNMP Management Frameworks", RFC 2571, 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, RFC 1212, March 1991.
[4] Rose, M., "A Convention for Defining Traps for use with the SNMP", RFC 1215, 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, RFC 2578, April 1999.
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[6] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999.
[7] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999.
[8] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, May 1990.
[9] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, January 1996.
[10] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, January 1996.
[11] Case, J., Harrington D., Presuhn R. and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2572, April 1999.
[12] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, April 1999.
[13] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, 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 (VACM) for the Simple Network Management Protocol (SNMP)", RFC 2575, April 1999.
[16] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction to Version 3 of the Internet-standard Network Management Framework", RFC 2570, April 1999.
[17] Daniele, M., Wijnen, B., Ellison, M. and D. Francisco, "Agent Extensibility (AgentX) Protocol, Version 1", RFC 2741, January 2000.
[18] Rose, M., "SNMP MUX Protocol and MIB", RFC 1227, May 1991.
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[19] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Management Information Base for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1907, January 1996.
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