#firewall

Create an outbound Windows Firewall rule that cuts a program off from the network.

Turn the built-in macOS application firewall on or off, and allow specific apps, via the socketfilterfw command.

Show the on/off state of all three firewall profiles with one netsh command.

Revert firewall rules and profiles to the out-of-box configuration with one command.

Permanently allow a TCP or UDP port through firewalld on Fedora, RHEL, or CentOS so your web app or game server is reachable.

One command to dump the default zone's services, open ports, and rich rules — the firewalld equivalent of a ruleset view.

Create an inbound allow rule for a TCP/UDP port with one PowerShell cmdlet, and delete it cleanly afterwards.

Create a deny rule for an IP or subnet with one PowerShell command — no GUI digging required.

Create an inbound firewall rule for ICMPv4 echo requests so the PC answers ping.

The pf-style GUI firewall is driven by /usr/libexec/ApplicationFirewall/socketfilterfw — fully scriptable.

Query whether Defender Firewall is enabled per profile (Domain/Private/Public) and list the rules already in place — without touching the GUI.

fail2ban runs silently for months — when you suddenly can't SSH in from your own IP, this is the command that tells you whether the jail banned you.