Circles of Trust - Firewalls

After you ensure your passwords are strong and known only to you, you need to ensure your router is properly configured. I discussed these steps in my two previous posts of this series. In this article, we will talk about firewalls, what they are, where and how to use them.

As I have said before, Internet security should be implemented in layers. No one layer offers sufficient protection. Another layer you should always use is a firewall. A firewall is a guard at the door between two networks. It decides who and what goes through the door in both directions. If you have a door connecting your private network or computer with the Internet, you NEED a good door guard!

I will not try and describe how they work in detail. I began to, then realized after typing three paragraphs, that most people don’t need to understand the detail and, there is way too much of it! Technical types can argue about the nuances and exceptions to my explanation, but for most people, it is enough to understand firewalls at a basic level.

Firewalls control which applications on one computer can talk to which applications on another computer. Think of a firewall as a filter that can be configured to block or allow traffic to and from the Internet. You can filter traffic based upon the type (applications, i.e.: ftp, file sharing, etc.), and the source (particular computers or networks). Firewall configurations usually begin by blocking everything. Then exceptions are added as they are required. All firewalls can be configured to allow exceptions, including the firewall that comes with Windows.





Most personal firewalls like the one that comes with Windows, are already configured for the most common uses and block many applications that you do not normally use. The default configuration of Windows Firewall is a great place to start. Just make sure it is turned on! You can access Windows Firewall from Control Panel.

Consider the following list of rules. Traffic coming from the Internet must meet each requirement starting with the first, before it is allowed through to your computer.












Windows Firewall is configured by entering exceptions to its rules for blocking traffic. Most of the time, Windows will configure these exceptions as you require them. For example, if you were to configure Remote Desktop to allow computers to connect to your computer, Windows will add the required exception to its firewall.

You should be protected from computers on the Internet attempting to connect to your computer to use Remote Desktop, by your router. Your computer’s private address is not accessible from the internet directly unless you configure your router to allow it. However, if you want an added layer of security, you can configure the exception rule in Windows Firewall to only allow Remote Desktop from computers on your home network. Remote Desktop will also require your computer’s administrator's user name and password to connect, or another user's credentials that you specifically configured Remote Desktop to allow. I will talk about configuring routers to allow Remote Desktop and other applications from the Internet in a later post.

Even though your router can protect your computer by "hiding" its address from the Internet, you should always use a firewall. You may have a laptop you take with you to another network, or you may need to change your router configuration at some time.

The different layers of security work together to protect you. It is important that each layer is configured and secured properly. Passwords, routers, firewalls, anti-virus anti-spyware software, operating system and software patches and updates, common sense and vigilance are all important layers of security. So far, in the series “Who Do You Trust” we have talked about passwords, routers and firewalls. In my next article, I will write about anti-virus and anti-spyware software, and how you can protect yourself from viruses, spyware and other malware.





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For more on Internet Security:

From The USA Educational Foundation: Internet Safety For Adults


From Family Online Safety Institute:
Top Internet Safety Tips for Parents (PDF)


From US-CERT:
Advice about common security issues for
non-technical computer users