Windows Firewall: Public: Inbound connections
The DWORD value `1` selects Block as the default action for inbound connections under the public firewall profile.
since 0.9.8.11
Purpose
Show registry keys (1)
HKLM\Software\Policies\Microsoft\WindowsFirewall\PublicProfile\DefaultInboundAction
The DWORD value 1 selects Block as the default action for inbound connections under the public firewall profile. Windows Firewall applies this fallback after evaluating the effective firewall rules, blocking inbound traffic that is not permitted by a matching rule.
This setting applies only to network connections classified under the public profile. It does not change the default action for the domain or private profile, and it does not control outbound connections.
Notes
Security
Default-deny handling reduces the network-facing attack surface on public networks. Unless an effective allow rule applies, another network host cannot initiate a connection to a listening application or service on the device.
This is not an unconditional block on all inbound connections. Explicit allow rules normally override the default block action, while explicit block rules take precedence over conflicting allow rules. The setting therefore differs from shielded mode, which blocks inbound traffic regardless of other policy settings.
Possible side effects
Applications and services that require inbound connectivity are not reachable through the public profile unless an applicable allow rule is part of the effective policy. This can affect sharing, remote-management, and server functionality. The inbound default action does not by itself block outbound communication or response traffic associated with connections initiated by the device.
Notes
This registry value defines a per-profile default action; it does not enable Windows Firewall. It takes effect only while the public profile is active and its firewall is enabled. Separate rule-merging settings determine which locally or centrally supplied rules participate in the effective policy.
Microsoft documentation
Microsoft Learn: Windows security baseline – Windows Firewall: Public: Inbound connections
Microsoft Learn: Default Inbound Action registry value
Microsoft Learn: Windows Firewall rules