How to Block WebSites

Blocking websites from being accessed by your kids (or employees) could not be easier than with OpenDNS.

OpenDNS is a DNS-based web filtering system that is used by millions of people, schools and companies around the world.

Below you will find a segment about how OpenDNS blocks websites, but first let's look at some of the excellent features:

• Easy to set up; All you need to do is create an account and modify the DNS server settings on your Internet router or computer. No complicated software to install, learn about or configure
• Category-based website blocking system with more than 40 pre-defined categories such as porn, gambling, violence, file sharing etc.
  
  

  

• Integration with OpenDNS's "Phishtank" which auto-blocks known phishing sites
• Automatically blocks known malware sites
  
  

  

• Fine-tune parental control by specifically allowing (whitelisting) or blocking (blacklisting) certain sites
• 5 pre-defined blocking levels for easy configuration
• Since it is DNS based, it works with all Operating Systems
• Statistics such as which web sites were visited, which ones were blocked etc
• It is completely free

OpenDNS has a pretty big community of users, many of which frequent the support forums. There also is a nice Knowledge Base in case you have questions or issues.

Here are two introductory OpenDNS videos. The first one walks you through the sign-up process, and the second one shows you some of the blocking / surfing statistics that can be logged.

In case you're not familiar with the inner workings of Internet traffic, here's short and simplified explanation that will help you understand how systems like OpenDNS work, and how they can block very specific sites instantly.

Part of how computers on the Internet communicate is the Internet Protocol (IP). Each computer (your home computer, a web server etc.) has an IP Address. In computer networks, computers can find each other based on their IP address, which looks something like this: 174.121.227.2.

Remembering IP addresses may be easy for computers, but for most people it is easier to remember names than numbers, so the Domain Name System (DNS) was invented.

Because of DNS we can say "visit me at www.mysuperawesomewebsite.com" instead of "visit my site at 64.40.111.31"

The output of the ping command above (which is computerish for "Hey are you there?") shows how the computer translates www.squidoo.com to an IP address instantly.

Besides an IP address, you computer also has a record for its designated DNS Server. This usually is the DNS server that is assigned to you by your Internet Service Provider.

A DNS Server (also referred to as a Domain Name Server) is a special server that holds a database of pairs of web site names and IP addresses. It keeps track of which IP Addresses belong to which websites.

To illustrate, here is the output of a query to such a DNS Server (in this case the server is 8.8.8.8, or one of Google's public DNS servers), which asks for the IP adress of my awesome online storage reviews web site:

In similar fashion, when you type in a web site name in your web browser, such as www.squidoo.com, a process called name resolution occurs in the background. Here are the (simplified) steps that take place in the blink of an eye:

• You type in www.squidoo.com and hit enter
• Your computer checks which DNS Server it is supposed to use
• Your computer asks the DNS Server "where is www.squidoo.com"?
• The DNS Server responds "www.squidoo.com is at IP adress 64.40.111.31"
• Your computer sends requests to retrieve the web site at IP Address 64.40.111.31
• The web site loads in your browser

And this is where OpenDNS can do its website blocking magic.

By changing your home network's DNS server settings to point to the OpenDNS domain name servers you enable OpenDNS to do domain name lookups for all internet traffic from your computer and / or network.

This means that for every website request, OpenDNS checks its huge database of categorized websites and malicious domains and can instantly block website access whenever a request for a site in a known blocked category is made.

The beauty of this is that you do not have to maintain, update or configure anything. The OpenDNS team / community constantly categorizes sites, keeping the database current and blocking rules effective.

If a website that your kids try to browse to matches a certain category (like gambling) the DNS server will block the request and serve up a (customizable) access denied page to the child, like so:

From the screenshot you can also see how it is that OpenDNS is free; it is ad-supported.

Every block page that it shows has ads on it. This does not bother me, but if it does bother you, OpenDNS offers the ad-free VIP version for only $9.95 per year. I would start out with the free version though, you can always upgrade to the ad-free version once you decide OpenDNS is a website blocking solution that meets your needs.

Also note that the block page can be modified. You can use your own picture and create your own message that will appear when a site is blocked.

Microsoft provides Windows users with a very nice add-on called Family Safety.

The Family Safety software is part of the Microsoft Windows Live Essentials 2011 software package that does not come pre-installed on new Windows computers. You have to download it separately.

More on the nice Family Safety add-on later this week. For now, check out the web site