Firewall Fact Sheet

This document is intended to help people who need IT support in Devon and advice about installing or testing their firewall.


A hardware firewall is preferable to a software firewall. Many routers have an inbuilt firewall.

Windows XP has its own firewall. Service Pack2 installs the security centre and places shortcuts in the control panel.

Zone Alarm offer a free firewall for home use:

Test your Firewall

There is a firewall test on the Symantec website:

This utility will test a firewall and PC for weaknesses visible from the Internet. These include: open ports, Windows Vulnerability, Trojan Horse Vulnerability and Antivirus Product Check.

 Firewall ports have one of three settings:

  • An open port responds to port probes and acknowledges the ports availability. Open ports are dangerous because they are an easy means of entry for hackers.
  • A closed port is visible but not open to attack. Although this is a safe state, a hacker can use closed ports to detect the existence of your computer and potentially target it for attack.
  • A stealth port is safest of all. Stealth means your firewall does not respond to port probes and you are virtually invisible to hackers scanning the Internet for potential targets. Although this is a very safe result, a stealth port may cause performance problems for some Internet applications.

Windows Vulnerability

Windows Vulnerability Check - also on the Symantec website - tests whether basic information, including your PC's network identity, can be seen by hackers.

Trojan Horse Check attempts to test for access to your computer through methods commonly used by Trojan Horses.

Antivirus Product Check checks for a current version of a commonly-used virus protection product.

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