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    1.0.0 • Public • Published


    NPM version

    SyslogProtocol.js is a Syslog (RFC 3164) format parser that supports high-precision timestamps (RFC 3339, ISO 8601).

    Given a Syslog message with a high-precision timestamp:

    <38>1987-06-18T15:20:30.337Z server sshd[42]: Accepted publickey for user

    It'll return the following object (with time being an instance of Date):

    { facility: "auth",
      facilityCode: 4,
      severity: "info",
      severityCode: 6,
      time: new Date("1987-06-18T15:20:30.337Z"),
      host: "server",
      process: "sshd",
      pid: 42,
      message: "Accepted publickey for user" }

    Ironically, SyslogProtocol.js does not support plain RFC 3164's timestamps, which are in who-knows-what time zone and lack a year part. If you can, don't use them. If you're really keen on them, please let me know and I'll see about implementing.


    • Supports RFC 3164 with high-precision timestamps (RFC 3339, ISO 8601).
      For example, Rsyslog's RSYSLOG_ForwardFormat uses those.
    • Supports colon-less TAG/process identifiers/messages (which Heroku log drains send).
    • Facility and severity names are <syslog.h> and syslog(3) compatible.
    • All property names of the returned object have gone through serious sincere consideration and are amazingly well chosen.


    npm install syslog-protocol


    Just require SyslogProtocol.js and use its parse function:

    var SyslogProtocol = require("syslog-protocol")
    var msg = "<38>1987-06-18T15:20:30.337Z server sshd[42]: Accepted publickey"

    Alphanumeric process identifiers

    SyslogProtocol.js can also handle alphanumeric process identifiers (sshd[foo]). For example, given Heroku's forwarded log:

    <158>1987-06-18T15:20:30.337Z d.550e8400-e29b-41d4-a716-446655440000 heroku[router] at=info method=GET path=/

    SyslogProtocol.js will return:

    { facility: "local3",
      facilityCode: 19,
      severity: "info",
      severityCode: 6,
      time: new Date("1987-06-18T15:20:30.337Z"),
      host: "d.550e8400-e29b-41d4-a716-446655440000",
      process: "heroku",
      pid: "router",
      message: "at=info method=GET path=/" }


    The returned object from parse has the following properties:

    Property Description
    facility Facility name. See below for a full list of facilities.
    facilityCode Facility numeric code.
    severity Severity name. See below for a full list of severities.
    severityCode Severity numeric code.
    time Date instance from the timestamp.
    host Hostname or IP address.
    process Process name.
    pid Process identifier (taken from brackets after process name).
    If the message lacks one, pid won't be set at all.
    If it looks like a number, it'll be cast to Number.
    message Rest of the message.


    Facility names returned by SyslogProtocol.js match <syslog.h> and syslog(3).

    Code Facility
    0 kern
    1 user
    2 mail
    3 daemon
    4 auth
    5 syslog
    6 lpr
    7 news
    8 uucp
    9 cron
    10 authpriv
    11 ftp
    12 ntp
    13 logaudit
    14 logalert
    15 clock
    16 local0
    17 local1
    18 local2
    19 local3
    20 local4
    21 local5
    22 local6
    23 local7


    Severity names returned by SyslogProtocol.js match <syslog.h> and syslog(3).
    Blame them for the inconsistent naming.

    Code Severity
    0 emerg
    1 alert
    2 crit
    3 err
    4 warning
    5 notice
    6 info
    7 debug


    SyslogProtocol.js is released under a Lesser GNU Affero General Public License, which in summary means:

    • You can use this program for no cost.
    • You can use this program for both personal and commercial reasons.
    • You do not have to share your own program's code which uses this program.
    • You have to share modifications (e.g. bug-fixes) you've made to this program.

    For more convoluted language, see the LICENSE file.


    Andri Möll typed this and the code.
    Monday Calendar supported the engineering work.

    If you find SyslogProtocol.js needs improving, please don't hesitate to type to me now at or create an issue online.


    npm i syslog-protocol

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