Floating Rules are advanced Firewall Rules which can apply in any direction and to any or multiple interfaces. Floating Rules are defined under Firewall > Rules on the Floating tab.
Many firewalls do not need any Floating Rules, or may only have them for the traffic shaper. For those choosing to use them, they can make some complex filtering scenarios easier, at the cost of being a little harder to follow logically in the GUI.
More advanced/low-level options are available on Floating Rules than can be found on normal per-interface rules.
Floating Rules can:
Filter traffic from the firewall itself
Filter traffic in the outbound direction (all other tabs are Inbound processing only)
Apply rules to multiple interfaces
Apply filtering in a “last match wins” way rather than “first match wins” (quick)
Apply traffic shaping to match traffic but not affect it’s pass/block action
Floating Rules are parsed before rules on other interfaces. Thus, if a packet matches a floating rule and the Quick option is active on that rule, pfSense will not attempt to filter that packet against any rule on any other group or interface tab.
Rules using the Queue action do not work with quick checked.