Most households today have a fixed internet service in their home-typically provided by an Internet Service Provider (ISP) that could be your phone company or a cable company or some such provider. There is typically an internet router that connects to the internet on one side through the modem provided by the ISP and on the other side creates a Wifi network to which multiple computers, smartphones and other devices in the home can connect. To effectively control internet access in your home network, it is important to understand two concepts – IP address and DNS.
An IP address is simply a unique number that any computer or device in your home acquires when it connects to your Wifi router. When you connect to a website on the internet, your computer needs to send messages to the remote computer server on which the website is running. At the same time the remote web server needs to send the website data back to your computer. IP addresses are how the two computers identify and connect to each other over the internet. The Internet is essentially a global network of computers that can route messages from one computer to another based on the IP address of the sender and the recipient (a little bit like a virtual version of the global postal system that routes letters from one postal address to another).
DNS stands for Domain Name System and is a method by which your computer can lookup a human readable internet address for a computer server on which a website is running, (like “www.google.com”) in a directory or address book and associate it with an IP address. So when you ask your browser to go to a website (for example http://www.google.com) it uses DNS to convert “www.google.com” to the IP address of the computer server on which the web site is running. Once it knows the IP address, your computer can shoot a message into cyberspace with the IP address of the remote server. All the internet then does is ensure your computer’s message reaches the target computer no matter where in the world it is located and routes the reply back to your computer. Everything happens in less than a second and you are “browsing” the internet! DNS works as a service running on bunch of computers on the internet that can keep a very up to date global address book of all internet connected computers in the world. When your computer wants to translate a human readable web address to an IP address it simply sends a message to a computer running DNS (known as a DNS server) and receives a response in a split second.
Why is DNS important?
Without the DNS system, your computer would not know how to send a message to any website and would require you to instead remember every website’s IP address. Obviously this is impractical for many reasons. Firstly, each webpage might contain data that is actually residing on multiple different computer servers and you would have to remember the IP address of dozens of websites just to load a single web page. Secondly, in order to optimise data traffic over the internet the companies that run these websites often keep updating and shuffling around the IP addresses all the time rendering your private address book completely out of date very quickly.
Controlling internet access
One very innovative way then to control access to websites from your home network is to start using a DNS service that can filter out the desirable from the undesirable sites on the internet. Thus when any computer on your network wants to connect to a website you consider undesirable, the DNS service would simply refuse to provide the IP address, making it impossible for you to access the website. In my next post I will describe how you can force users on your home network to use a DNS service from a company called OpenDNS that provides the control you require and allows you to be the decider of what is and isn’t desirable.