The Syslog Protocol
RFC 5424

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Network Working Group                                        R. Gerhards
Request for Comments: 5424                                  Adiscon GmbH
Obsoletes: 3164                                               March 2009
Category: Standards Track

                          The Syslog Protocol

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.

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   Without obtaining an adequate license from the person(s) controlling
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   it for publication as an RFC or to translate it into languages other
   than English.

Gerhards                    Standards Track                     [Page 1]
RFC 5424                  The Syslog Protocol                 March 2009

Abstract

   This document describes the syslog protocol, which is used to convey
   event notification messages.  This protocol utilizes a layered
   architecture, which allows the use of any number of transport
   protocols for transmission of syslog messages.  It also provides a
   message format that allows vendor-specific extensions to be provided
   in a structured way.

   This document has been written with the original design goals for
   traditional syslog in mind.  The need for a new layered specification
   has arisen because standardization efforts for reliable and secure
   syslog extensions suffer from the lack of a Standards-Track and
   transport-independent RFC.  Without this document, each other
   standard needs to define its own syslog packet format and transport
   mechanism, which over time will introduce subtle compatibility
   issues.  This document tries to provide a foundation that syslog
   extensions can build on.  This layered architecture approach also
   provides a solid basis that allows code to be written once for each
   syslog feature rather than once for each transport.

   This document obsoletes RFC 3164.

Table of Contents

   1. Introduction ....................................................4
   2. Conventions Used in This Document ...............................4
   3. Definitions .....................................................4
   4. Basic Principles ................................................5
      4.1. Example Deployment Scenarios ...............................6
   5. Transport Layer Protocol ........................................7
      5.1. Minimum Required Transport Mapping .........................7
   6. Syslog Message Format ...........................................8
      6.1. Message Length .............................................9
      6.2. HEADER .....................................................9
           6.2.1. PRI .................................................9
           6.2.2. VERSION ............................................11
           6.2.3. TIMESTAMP ..........................................11
           6.2.4. HOSTNAME ...........................................13
           6.2.5. APP-NAME ...........................................14
           6.2.6. PROCID .............................................14
           6.2.7. MSGID ..............................................14
      6.3. STRUCTURED-DATA ...........................................15
           6.3.1. SD-ELEMENT .........................................15
           6.3.2. SD-ID ..............................................15
           6.3.3. SD-PARAM ...........................................16
           6.3.4. Change Control .....................................17
           6.3.5. Examples ...........................................17

Gerhards                    Standards Track                     [Page 2]
RFC 5424                  The Syslog Protocol                 March 2009