20.conf

filter {

  if [type] == "syslog" {

    grok {

      match => { "message" => "%{SYSLOGTIMESTAMP:syslog_timestamp} %{SYSLOGHOST:syslog_hostname} %{DATA:syslog_program}(?:\[%{POSINT:syslog_pid}\])?: %{GREEDYDATA:syslog_message}" }

      add_field => [ "received_at", "%{@timestamp}" ]

      add_field => [ "received_from", "%{host}" ]

    }

    syslog_pri { }

    date {

      match => [ "syslog_timestamp", "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]

    }

  }

}