> For the complete documentation index, see [llms.txt](https://docs.fluentd.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fluentd.org/parser/syslog.md). # syslog The `syslog` parser plugin parses `syslog` generated logs. This plugin supports two RFC formats, RFC-3164 and RFC-5424. ## Parameters See [Parse Section Configurations](/configuration/parse-section.md). ### `time_format` | type | default | version | | ------ | -------------- | ------- | | string | %b %d %H:%M:%S | 0.14.10 | Specifies the time format for the event time. Default is `"%b %d %H:%M:%S"` for RFC-3164 protocol. If your log uses sub-second timestamp, change this parameter to `"%b %d %H:%M:%S.%N"`. ### `rfc5424_time_format` | type | default | version | | ------ | ---------------------- | ------- | | string | %Y-%m-%dT%H:%M:%S.%L%z | 0.14.14 | Specifies the event time format for the RFC-5424 protocol. ### `message_format` | type | default | available values | version | | ---- | ------- | -------------------- | ------- | | enum | rfc3164 | rfc3164/rfc5424/auto | 0.14.14 | Specifies the protocol format. Supported values are `rfc3164`, `rfc5424` and `auto`. Default is `rfc3164`. If your `syslog` uses `rfc5424`, use `rfc5424` instead. `auto` is useful when this parser receives both `rfc3164` and `rfc5424` message. `syslog` parser detects message format by using message prefix. ### `with_priority` | type | default | version | | ---- | ------- | ------- | | bool | false | 0.14.0 | If the incoming logs have priority prefix e.g. `<9>`, set `true`. Default is `false`. This parameter is used inside `in_syslog` plugin because the file logs via `syslog` do not have `<9>` like priority prefix. ### `parser_type` | type | default | available values | version | | ---- | ------- | ---------------- | -------------------------------------- | | enum | regexp | regexp/string | 1.7.1(for rfc3164)/1.11.0(for rfc5424) | Specifies the internal parser type for `rfc3164`/`rfc5424` format. Supported values are `regexp` and `string`. Both parsers generate the same record for the standard format. If `regexp` does not work for your logs, consider `string` type instead. We recommend using `string` parser because it is 2x faster than `regexp`. The default is `regexp` for existing users. Fluentd v2 will change the default to `string` parser. ### `support_colonless_ident` | type | default | version | | ---- | ------- | ------- | | bool | true | 1.7.1 | This parameter is used when `parser_type` is `string`. If your message does not contain the ident field, set `false` to avoid ident mismatch. ``` # No ident field log Feb 5 17:32:18 10.0.0.99 Use the BFG! # generated record with true is wrong {"host":"10.0.0.99","ident":"Use","message":"the BFG!"} # generated record with false is correct {"host":"10.0.0.99","message":"Use the BFG!"} ``` ## Regexp Patterns Show regexp patterns for parsing logs. ### RFC-3164 Pattern ``` expression /^\<(?[0-9]+)\>(?[^ ]* {1,2}[^ ]* [^ ]*) (?[^ ]*) (?[^ :\[]*)(?:\[(?[0-9]+)\])?(?:[^\:]*\:)? *(?.*)$/ time_format "%b %d %H:%M:%S" ``` `pri`, `host`, `ident`, `pid` and `message` are included in the event record. `time` is used for the event time. `pri` value is converted to the integer type. If `with_priority` is `false`, `^\<(?[0-9]+)\>` is removed from the pattern. ### RFC-5424 Pattern ``` expression /\A\<(?[0-9]{1,3})\>[1-9]\d{0,2} (?[^ ]+) (?[!-~]{1,255}) (?[!-~]{1,48}) (?[!-~]{1,128}) (?[!-~]{1,32}) (?(?:\-|(?:\[.*?(?.+))?\z/ time_format "%Y-%m-%dT%H:%M:%S.%L%z" ``` `pri`, `host`, `ident`, `pid`, `msgid`, `extradata` and `message` are included in the event record. `time` is used for the event time. `pri` value is converted to the integer type. If `with_priority` is `false`, `\<(?[0-9]{1,3})\>[1-9]\d{0,2}` is removed from the pattern. ## Example ### RFC-3164 Log This incoming event: ``` <6>Feb 28 12:00:00 192.168.0.1 fluentd[11111]: [error] Syslog test ``` is parsed as: ``` time: 1362020400 (Feb 28 12:00:00) record: { "pri" : 6, "host" : "192.168.0.1", "ident" : "fluentd", "pid" : "11111", "message": "[error] Syslog test" } ``` ### RFC-5424 Log This incoming event: ``` <16>1 2013-02-28T12:00:00.003Z 192.168.0.1 fluentd 11111 ID24224 [exampleSDID@20224 iut="3" eventSource="Application" eventID="11211"] Hi, from Fluentd! ``` is parsed as: ``` time: 1362052800 (2013-02-28T12:00:00.003Z) record: { "pri" : 16, "host" : "192.168.0.1", "ident" : "fluentd", "pid" : "11111", "msgid" : "ID24224", "extradata": "[exampleSDID@20224 iut=\"3\" eventSource=\"Application\" eventID=\"11211\"]", "message" : "Hi, from Fluentd!" } ``` If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.fluentd.org/parser/syslog.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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