Originally published at: https://www.cyberciti.biz/faq/enable-firewalld-logging-for-denied-packets-on-linux/
How do I enable firewalld logging for denied packets on Linux operating systems so that I can view all dropped packets information? How can I view a log of the traffic blocked by FirewallD under a CentOS/RHEL (Red Hat Enterprise Linux)/Suse/OpenSUSE Linux?