If you have ever set up your Internet connection or watched your ISP technician set up your account, I'm sure you've seen or heard of your TCP/IP settings. One of the TCP/IP settings is the DNS. DNS stands for (D)omain (N)ame (S)ystem. It's a neat system that helps a computer know how to get around the Internet.
Places on the Internet, much like places we live, all have addresses. But the addresses on the Internet are not anything like the nice names we have like http://bytesforeveryone.blogspot.com/. They are a set of numbers separated by dots or colons. I'm not going to go into Internet addresses, or IP addresses here. In this blog entry, I'm focusing on DNS.
Whatever the address is, people usually can't remember big numbers as well as unique names such as http://bytesforeveryone.blogspot.com/. So there has to be one big "phone book" which correlates these addresses to the unique names. That, in fact, is exactly what is going on. There are many DNS servers all over the Internet which are designed to "look up" addresses by unique names. The DNS servers you use in your TCP/IP settings most likely pass the lookup request to other more "authoritative" servers at strategic locations around the Internet.
So, here's how it goes. When you type in http://bytesforeveryone.blogspot.com/ in your browser, the computer goes out and makes a "DNS request" to your DNS server to convert the name to an IP address. Then the browser goes out to that IP address to get the web page. One thing that always amazes me is how FAST all that takes place.
Looking at my blog title, you might be asking yourself, what does DNS or address lookups have to do with content filtering? By content filtering, I mean the ability to filter out - or block - certain content from the web to my home.
Well, I wanted to find an inexpensive way to filter Internet content to my home. There are so many software solutions out there for this - and I can hear you all telling me which ones you might be using - if any. Another piece of software to load and which to subscribe didn't make me happy and I wanted a way to do this at my main Internet connection point inexpensively. Things were looking dismal as I was not able to find anything inexpensive. I found all sorts of expensive firewall-type devices and services. All of which didn't seem to suit my needs as I'm always looking for solutions that home users can afford or can set up.
Here's what I did. I found that there is a company called OpenDNS who has their own DNS servers which you can use for free. If you sign up for a free account with them, you can actually use their servers to filter content! In order to get the content filtering, you must sign up for the free account. They have a pay version as well, but that's not necessary for home networks. Here's the link for home users: http://www.opendns.com/solutions/household/
At the time of this writing OpenDNS has 2 DNS servers: 208.67.222.222 and 208.67.220.220. Once you set up your OpenDNS account, you simply put these 2 DNS servers in your network router. When you do this, the router will feed these DNS server addresses to all of your home PC's, unless you have a smarty pants who knows how to bypass the settings distributed by the router.
Once you set up your OpenDNS account, you can configure what types of content you want to filter. I have found it to be very good at what it does and it's pretty good for the price.
Until next time.
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