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Contents The HEADER message part

The HEADER part contains the following elements:

  • VERSION: Version number of the syslog protocol standard. Currently this can only be 1.

  • ISOTIMESTAMP: The time when the message was generated in the ISO 8601 compatible standard timestamp format (yyyy-mm-ddThh:mm:ss+-ZONE), for example: 2006-06-13T15:58:00.123+01:00.

  • HOSTNAME: The machine that originally sent the message.

  • APPLICATION: The device or application that generated the message

  • PID: The process name or process ID of the syslog application that sent the message. It is not necessarily the process ID of the application that generated the message.

  • MESSAGEID: The ID number of the message.


The syslog-ng application supports other timestamp formats as well, like ISO, or the PIX extended format. The timestamp used in the IETF-syslog protocol is derived from RFC3339, which is based on ISO8601. For details, see the ts-format() option in Section 9.2, Global options.

The syslog-ng PE application will truncate the following fields:

  • If APP-NAME is longer than 48 characters it will be truncated to 48 characters.

  • If PROC-ID is longer than 128 characters it will be truncated to 128 characters.

  • If MSGID is longer than 32 characters it will be truncated to 32 characters.

  • If HOSTNAME is longer than 255 characters it will be truncated to 255 characters.