OpenDNS - A filtering service and an explanation of how it works
OpenDNS offers what is presently a free filtering service. I am describing the service here because the service is available to you if you are interested and because the details of how it works are interesting.The role played by a domain name server (DNS) was decribed in Chapter 5. A DNS functions to translate the web address we enter (e.g., http://ndwild.psych.und.nodak.edu) into the IP of the server (e.g., 134.129.172.86). This translation is necessary because servers and routers use this number to route the information you request back to your computer and browser. A DNS is a computer which exists primarily to perform this basic translation function.
OpenDNS works by performing tasks in addition to this word to number translation. In addition to a database of web sites and IP equivalents, OpenDNS stores information on other attributes of the site. Is the site a known phishing site? Does the site show nudity, pornography, or sexuality? When signing up for OpenDNS, you check off characteristics you do not want to view. You can also take a different approach (called a white list). You can request that you be allowed to display only those sites on an approved list. The difference is that the attributes of some sites may not be known (not on the white list and not in the database) and the decision when using the "white list" is to avoid the site.
Here is how OpenDNS works. You set up your computer preferences to use OpenDNS as your DNS. Your computer may originally use a different DNS or to default to the DNS selected by your service provider. You also set up an account on OpenDNS and specify what if any filtering options you want to implement (OpenDNS provides some other services which are not relevant here, but filtering is not a requirement for using OpenDNS as your DNS). Once these tasks are completed, requests from any browser are routed through OpenDNS, the request is checked against the expectations you have established, and the request for the return of web content is sent to the designated server only when the site satisfies the qualifications you have established.
OpenDNS makes money by showing ads (I assume you wondered how companies such as this make money). I use OpenDNS on my office machine and I must say that I am not certain what showing ads means for certain. I have not noticed ads in the sense that one notices ads when doing a Google search. I mention this because some may object to this practice and I wanted to be clear in identifying what for some is an issue.
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