Graylog

Graylog can't run on privileged ports as non-root user, but you can make a forward from UDP standard port 514 to non standard 5140 that uses Graylog.

$ sudo firewall-cmd --set-default-zone=trusted
$ sudo firewall-cmd --zone=trusted --add-masquerade --permanent
$ sudo firewall-cmd --zone=trusted --add-forward-port=port=514:proto=udp:toport=5140 --permanent
$ sudo firewall-cmd --reload