If you want to send syslog from other devices, you should check to see if the device has an existing Filebeat module at https://www.elastic.co/guide/en/beats/filebeat/current/filebeat-modules.html. If so, using the Filebeat module should provide some parsing by default.
If your device does not have an existing Filebeat module, you can still collect standard syslog by running so-allow on the manager and then choosing the
syslog option to allow the port through the firewall. If sending syslog to a sensor, please see the Examples in the Firewall section. If you need to add custom parsing for those syslog logs, we recommend using Elasticsearch ingest parsing.
Also note that if you’re monitoring network traffic with Zeek, then by default it will detect any syslog in that network traffic and log it even if that syslog was not destined for that particular Security Onion node.