graylog server | sidecar | filebeat | syslog udp
on the Graylog server web UI
first, you need to prepare the Graylog server to receive those beats as an input method
    System / Input
    Beats > Launch new input
    check   "Global"
    title   beats
    bind    0.0.0.0
    port    5044
on the Graylog server web UI
also create a Sidecar configuration to grab the log files with. change log location and target listener
    System / Sidecars --> Configuration
    Crate Configuration
    name            ...filebeat-linux-cutstom
    color           ...
    collector       filebeat on Linux
    fields_under_root: true
    fields.collector_node_id: ${sidecar.nodeName}
    fields.gl2_source_collector: ${sidecar.nodeId}
    filebeat.inputs:
    - input_type: log
      paths:
      - /var/log/messages
      - /var/log/syslog
      - /var/log/*/*log
      type: log
    output.logstash:
       hosts: ["graylog-server:5044"]
    path:
      data: /var/lib/graylog-sidecar/collectors/filebeat/data
      logs: /var/lib/graylog-sidecar/collectors/filebeat/log
on the Graylog server web UI
enable Filebeat for the hosts you want managed that way
    System > Sidecars / Administration
    enable Filebeat on the newly appeared node