What Is Windows Firewall?

Windows Firewall first appeared with Windows 2000 as the Internet Connection Firewall (ICF). The initial version was a rudimentary firewall — basic in both its functionality and its limited feature set. In short, it was a very simple firewall. Since then, each new version of Windows has brought an improved Windows Firewall. Today, the firewall that comes with Windows 10 is capable of meeting our requirements.

The latest version of the firewall introduced with Windows 10 can be configured to block both inbound and outbound packets. To access the Windows 10 firewall, simply click the Start button and type Windows Firewall.

Starting from Windows Server 2008 and all subsequent versions, Windows Firewalls come with stateful packet inspection. With the Windows 10 Firewall, you can set different rules for outbound and inbound traffic, and configure it for different network types — Public or Home/Work.

Using Windows Firewall

You have the option to use a connection (port), an application, a custom rule, or any of the many pre-defined rules available from Microsoft. You can also choose not just to allow or block a connection, but also to allow it only if it is secured by IPSec. At this point, Windows Firewall is configured to offer you three options for any given connection.

Rules allow or block a specific application or port. You can also have different rules for inbound and outbound traffic. Rules also allow you to determine whether a particular type of communication should be blocked. You can have separate settings for inbound and outbound traffic, and you can set rules for individual ports (65,554 available ports) and applications.

In short, the rules within Windows Firewall provide a great deal of flexibility while also being easy to use. More importantly, you can apply rules differently depending on where the traffic is coming from.

• Domain: Used for computers authenticated within your domain.
• Public: Used for computers outside your network.
• Private: Refers to traffic originating from your own computer — i.e. private/local definitions.

Administrators must always take the following rules into account with all packet-filtering firewalls:

• If a port is open and you do not need it, block it without exception.
• Unless it is absolutely necessary, always block ICMP traffic, as many utilities such as ping, tracert, and numerous port scanners use ICMP packets.
• Write specific rules for traffic coming from external networks.

Windows Firewall also maintains log records. However, the logging feature is disabled by default. Enabling this feature is always beneficial.