11.4. Windows Firewall
Windows Firewall has been standard since Windows XP. In Windows XP SP2, it was enabled by default, and it has steadily improved over the years.
A firewall is designed to protect a computer or network by controlling inbound and outbound traffic. Most firewalls operate with an implicit deny philosophy. In other words, all traffic is blocked (implicit deny) unless there is a rule that explicitly allows the traffic.
Windows Firewall on Windows 7 also uses an implicit deny philosophy. The only traffic that is allowed is the following:
Traffic that is explicitly allowed by an exception or a rule. Both inbound and outbound rules can be configured.
Return traffic that has been requested. For example, if a user requests a web page ...