





Network Working Group                                        S. Chisholm
Request for Comments: 5674                                        Nortel
Category: Standards Track                                    R. Gerhards
                                                            Adiscon GmbH
                                                            October 2009


                            Alarms in Syslog

Abstract

   This document describes how to send alarm information in syslog.  It
   includes the mapping of ITU perceived severities onto syslog message
   fields.  It also includes a number of alarm-specific SD-PARAM
   definitions from X.733 and the IETF Alarm 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) 2009 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 BSD License.













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Table of Contents

   1. Introduction ....................................................2
   2. Severity Mapping ................................................2
   3. Alarm STRUCTURED-DATA Elements ..................................3
      3.1. resource ...................................................3
      3.2. probableCause ..............................................4
      3.3. perceivedSeverity ..........................................4
      3.4. eventType ..................................................4
      3.5. trendIndication ............................................4
      3.6. resourceURI ................................................5
   4. Examples ........................................................5
   5. Security Considerations .........................................6
   6. IANA Considerations .............................................6
   7. Acknowledgments .................................................6
   8. References ......................................................7
      8.1. Normative References .......................................7
      8.2. Informative References .....................................7

1.  Introduction

   In addition to sending out alarm information asynchronously via
   protocols such as the Simple Network Management Protocol (SNMP) or
   the Network Configuration Protocol (Netconf), many implementations
   also log alarms via syslog.  This memo defines a set of SD-PARAMs to
   support logging and defines a mapping of syslog severity to the
   severity of the alarm.

   The Alarm MIB [RFC3877] includes mandatory alarm fields from X.733
   [X.733] as well as information from X.736 [X.736].  In additional,
   the Alarm MIB introduces its own alarm fields.  This memo reuses
   terminology and fields from the Alarm MIB.

   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].

   Alarm-related terminology is defined in [RFC3877].

   SD-ID, SD-PARAM, and other syslog-related terms are defined in
   [RFC5424].

2.  Severity Mapping

   The Alarm MIB [RFC3877] defines ITU perceived severities; it is
   useful to be able to relate these to the syslog message fields,
   particularly in the case where alarms are being logged.  This memo
   describes the representation of ITU perceived severities in



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   appropriate syslog fields, which are described in [RFC5424].  Syslog
   offers both a so-called SEVERITY as well as STRUCTURED-DATA.  Due to
   constraints in syslog, there is no one-to-one mapping possible for
   SEVERITY.  A STRUCTURED-DATA element is defined in this document to
   allow inclusion of the unmodified ITU perceived severity.

   Syslog supports Severity values different from ITU perceived
   severities.  These are defined in Section 6.2.1 of [RFC5424].  The
   mapping shown in Table 1 below SHOULD be used to map ITU perceived
   severities to syslog severities.

           ITU Perceived Severity      syslog SEVERITY (Name)
           Critical                    1 (Alert)
           Major                       2 (Critical)
           Minor                       3 (Error)
           Warning                     4 (Warning)
           Indeterminate               5 (Notice)
           Cleared                     5 (Notice)

        Table 1. ITUPerceivedSeverity to Syslog SEVERITY Mapping

3.  Alarm STRUCTURED-DATA Elements

   STRUCTURED-DATA allows the inclusion of any structured information
   into a syslog message.  The following are defined in this document to
   support the structuring of alarm information.

   o  Resource Under Alarm

   o  Probable Cause

   o  Event Type

   o  Perceived Severity

   o  Trend Indication

   o  Resource URI

   Support of the "alarm" SD-ID is optional but, once supported, some of
   the SD-PARAMS are mandatory.

3.1.  resource

   If the "alarm" SD-ID is included, the "resource" SD-PARAM MUST be
   included.  This item uniquely identifies the resource under alarm
   within the scope of a network element.




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3.2.  probableCause

   If the "alarm" SD-ID is included, the "probableCause" SD-PARAM MUST
   be included.  This parameter is the mnemonic associated with the
   IANAItuProbableCause object defined within [RFC3877] and any
   subsequent extensions defined by IANA.  For example,
   IANAItuProbableCause defines a transmission failure to a probable
   cause of 'transmissionError (10)'.  The value of the parameter in
   this case would be 'transmissionError'.

3.3.  perceivedSeverity

   If the "alarm" SD-ID is included, the "perceivedSeverity" SD-PARAM
   MUST be included.  Similar to the definition of perceived severity in
   [X.736] and [RFC3877], this object can take the following values:

   o  cleared

   o  indeterminate

   o  critical

   o  major

   o  minor

   o  warning

   See Section 2 for the relationship between this severity and syslog
   severity.

3.4.  eventType

   If the "alarm" SD-ID is included, the "eventType" SD-PARAM SHOULD be
   included.  This parameter is the mnemonic associated with the
   IANAItuEventType object defined within [RFC3877] and any subsequent
   extensions defined by IANA.  For example, IANAItuEventType defines an
   environmental alarm to an event type of 'environmentalAlarm (6)'.
   The value of the parameter in this case would be
   'environmentalAlarm'.

3.5.  trendIndication

   If the "alarm" SD-ID is included, the "trendIndication" SD-PARAM
   SHOULD be included.  Similar to the definition of perceived severity
   in [X.733] and [RFC3877], this object can take the following values:





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   o  moreSevere

   o  noChange

   o  lessSevere

3.6.  resourceURI

   If the "alarm" SD-ID is included, the "resourceURI" SD-PARAM SHOULD
   be included.  This item uniquely identifies the resource under alarm.

   The value of this field MUST conform to the URI definition in
   [RFC3986] and its updates.  In the case of an SNMP resource, the
   syntax in [RFC4088] MUST be used and "resourceURI" must point to the
   same resource as alarmActiveResourceId [RFC3877] for this alarm.

   Both the "resource" and the "resourceURI" parameters point at the
   resource experiencing the alarm, but the "resourceURI" has syntactic
   constraint requiring it to be a URI.  This makes it easy to correlate
   this syslog alarm with any alarms that are received via other
   protocols, such as SNMP, or to use SNMP or other protocols to get
   additional information about this resource.

4.  Examples

   Example 1 - Mandatory Alarm Information

   <165>1 2003-10-11T22:14:15.003Z mymachine.example.com
   evntslog - ID47 [exampleSDID@32473 iut="3" eventSource=
   "Application" eventID="1011"][alarm resource="su root"
   probableCause="unauthorizedAccessAttempt"
   perceivedSeverity="major"]
   BOMAn application event log entry...

   In this example, extended from [RFC5424], the VERSION is 1 and the
   Facility has the value of 4.  The severity is 2.  The message was
   created on 11 October 2003 at 10:14:15pm UTC, 3 milliseconds into the
   next second.  The message originated from a host that identifies
   itself as "mymachine.example.com".  The APP-NAME is "evntslog" and
   the PROCID is unknown.  The MSGID is "ID47".  We have included both
   the structured data from the original example, a single element with
   the value "[exampleSDID@32473 iut="3" eventSource="Application"
   eventID="1011"]", and a new element with the alarm information
   defined in this memo.  The alarm SD-ID contains the mandatory SD-
   PARAMS of resource, probableCause, and preceivedSeverity.  The MSG
   itself is "An application event log entry..."  The BOM at the
   beginning of the MSG indicates UTF-8 encoding.




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   Example 2 - Additional Alarm Information

   <165>1 2004-11-10T20:15:15.003Z mymachine.example.com
   evntslog - ID48 [alarm resource="interface 42"
   probableCause="unauthorizedAccessAttempt"
   perceivedSeverity="major"
   eventType="communicationsAlarm"
   resourceURI="snmp://example.com//1.3.6.1.2.1.2.2.1.1.42"]

   In this example, we include two optional alarm fields: eventType and
   resourceURI.

5.  Security Considerations

   In addition to the general syslog security considerations discussed
   in [RFC5424], the information contained with alarms may provide
   hackers with helpful information about parts of the system currently
   experiencing stress as well as general information about the system,
   such as inventory.

   Users should not have access to information in alarms that their
   normal access permissions would not permit if the information were
   accessed in another manner.

   There is no standardized access control model for syslog, and hence
   the ability to filter alarms based on a notion of a receiver identity
   is, at best, implementation specific.

6.  IANA Considerations

   IANA registered the syslog Structured Data ID values and PARAM-NAMEs
   shown below:

   SD-ID              PARAM-NAME
   alarm                                 OPTIONAL
                      resource           MANDATORY
                      probableCause      MANDATORY
                      perceivedSeverity  MANDATORY
                      eventType          OPTIONAL
                      trendIndication    OPTIONAL
                      resourceURI        OPTIONAL

7.  Acknowledgments

   Thanks to members of the Syslog and OPSAWG work group who contributed
   to this specification.  We'd also like to thank Juergen
   Schoenwaelder, Dave Harrington, Wes Hardaker, and Randy Presuhn for
   their reviews.



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8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3877]  Chisholm, S. and D. Romascanu, "Alarm Management
              Information Base (MIB)", RFC 3877, September 2004.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC4088]  Black, D., McCloghrie, K., and J. Schoenwaelder, "Uniform
              Resource Identifier (URI) Scheme for the Simple Network
              Management Protocol (SNMP)", RFC 4088, June 2005.

   [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.

8.2.  Informative References

   [X.733]    ITU-T, "Information Technology - Open Systems
              Interconnection - System Management: Alarm Reporting
              Function", ITU-T X.733, 1992.

   [X.736]    ITU-T, "Information Technology - Open Systems
              Interconnection - System Management: Security Alarm
              Reporting Function", ITU-T X.736, 1992.

Authors' Addresses

   Sharon Chisholm
   Nortel
   3500 Carling Ave
   Nepean, Ontario  K2H 8E9
   Canada

   EMail: schishol@nortel.com


   Rainer Gerhards
   Adiscon GmbH
   Mozartstrasse 21
   Grossrinderfeld, BW  97950
   Germany

   EMail: rgerhards@adiscon.com



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