Network Working Group S. Chisholm
Internet-Draft Nortel
Intended status: Standards Track R. Gerhards
Expires: November 27, 2009 Adiscon GmbH
May 26, 2009
Alarms in SYSLOG
draft-ietf-opsawg-syslog-alarm-02.txt
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Abstract
This document describes how to send alarm information in syslog. It
includes the mapping of ITU perceived severities onto syslog message
fields and a number of alarm-specific SD-PARAM definitions from X.733
and the IETF Alarm MIB.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Severity Mapping . . . . . . . . . . . . . . . . . . . . . . . 4
3. Alarm STRUCTURED-DATA Elements . . . . . . . . . . . . . . . . 5
3.1. resource . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. probableCause . . . . . . . . . . . . . . . . . . . . . . 5
3.3. perceivedSeverity . . . . . . . . . . . . . . . . . . . . 5
3.4. eventType . . . . . . . . . . . . . . . . . . . . . . . . 6
3.5. trendIndication . . . . . . . . . . . . . . . . . . . . . 6
3.6. resourceURI . . . . . . . . . . . . . . . . . . . . . . . 6
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 14
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1. Introduction
In addition to sending out alarm information asynchronously via
protocols such as SNMP or Netconf, many implementations also log
alarms via syslog. This memo defines a set of SD-PARAM to support
logging and defines a mapping of syslog severity to the severity of
the alarm.
The Alarm MIB (RFC 3877) included mandatory alarm fields from X.733
as well as information from X.736. In additional, the Alarm MIB
introduced 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].
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2. Severity Mapping
The Alarm MIB [RFC3877] defines ITU perceived severities which are
useful to be able to relate to the syslog message fields,
particularly in the case where alarms are being logged. This memo
describes the representation of ITU perceived severities in
appropriate syslog fields 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 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.
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3. Alarm STRUCTURED-DATA Elements
STRUCTURED-DATA allows to include any structured information into a
syslog message. The following are defined to support structuring
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-PARARMS are mandatory.
3.1. resource
If the "alarm" SD-ID is supported, the "resource" SD-PARAM MUST be
supported. This item uniquely identifies the resource under alarm
within the scope of a network element.
3.2. probableCause
If the "alarm" SD-ID is supported, the "probableCause" SD-PARAM MUST
be supported. 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 supported, the "perceivedSeverity" SD-PARAM
MUST be supported. Similar to the definition of perceived severity
in [X.736] and [RFC3877], this object can take the following values:
o cleared
o indeterminate
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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 supported, the "eventType" SD-PARAM SHOULD be
supported. This parameter is the mnemonic associated with the
IANAItuEventType object defined within [RFC3877] and any subsequent
extensions defined by IANA. For example, IANAItuEventType defines a
environmental alarm to a 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 supported, the "trendIndication" SD-PARAM
SHOULD be supported. Similar to the definition of perceived severity
in [X.733] and [RFC3877], this object can take the following values:
o moreSevere
o noChange
o lessSevere
3.6. resourceURI
If the "alarm" SD-ID is supported, the "resourceURI" SD-PARAM SHOULD
be supported. This item uniquely identifies the resource under
alarm.
The value of this field MUST conform to the URI definition in
[RFC1738] 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
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additional information about this resource.
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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 [Syslog], 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 "su" 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@0 iut="3" eventSource="Application"
eventID="1011"]" and a new one 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 MSG
indicates UTF-8 encoding.
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.
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5. Security Considerations
In addition to 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 was
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.
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6. IANA Considerations
IANA is requested to register the SD-IDs and PARAM-NAMEs shown below:
SD-ID PARAM-NAME
alarm OPTIONAL
resource MANDATORY
probableCause MANDATORY
perceivedSeverity MANDATORY
eventType OPTIONAL
trendIndication OPTIONAL
resourceURI OPTIONAL
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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
[RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
Resource Locators (URL)", RFC 1738, December 1994.
[RFC2119] Bradner, s., "Key words for RFCs to Indicate Requirements
Levels", RFC 2119, March 1997.
[RFC3877] Chisholm, S. and D. Romascanu, "Alarm Management
Information Base (MIB)", RFC 3877, September 2004.
[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.
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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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