DEFINITION

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Web content filtering is the practice of blocking access to web content that may be deemed offensive, inappropriate, or even dangerous. Families will be well aware of the need to apply internet content filters to material not suitable for young children, but content filtering has its place in the business world, too. 

There are many ways that content can be filtered for the user at a home oroffice. For parents at a home there primary concern may be pornography andchat rooms. For an owner or manager of a company your primary concernwould also include time wasting sites like online games, shopping, news, andmany more. Companies have a bigger challenge because they may haveemployees that need different levels of filtering. You may not want to blockeveryone from online shopping. There is probable someone that needs to dothat.

This article will talk about the basics of Internet content filtering. It will alsodescribe a filtering solutions created by PowerNOC that companies and ISP’scan use to create a filtering solution that can’t be circumvented

How does content filtering work?

Content filtering works by using hardware or software-based solutions to establish rules about the types of sites that may be visited. Using keywords or other commonalities between sites, content is grouped into categories—such as sports, gambling, adult, streaming, and so on—and those sites in undesirable categories are blocked on the network.

Keeping objectionable content away from children is one of the more obvious use cases for web content filtering. But DNS Filtering—a specific type of content filtering that uses the DNS layer to filter based on IP addresses—is increasingly being adopted by businesses as a means of controlling web use and reducing infections. When content is filtered according to sites known to pose a high risk of malware, those sites can be blocked before they have the chance to drop malicious payloads. When known distractions like social media and streaming video sites are blocked, productivity increases.

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Different Filtering Methods

There are a few different ways that filtering is done.Keyword Filtering is one of the simplest yet very ineffective ways offiltering. The program doing the filtering scans the URL and page that isbeing accessed. It looks for common keywords. Sex, breast, female aresome examples. This will block a fair amount of the unwanted pages.However, it has many downsides.

Pros – Such filtering programs are very inexpensive and even free.Cons – Does only a fair job at catching unwanted sites. Blocks too manywanted sites. For example, if you did a search for “breast cancer” the searchwould be blocked.Ways Around It – Using foreign words for sex, breast, female, etc. Ifsomeone is seeking out pornography they usually don’t care about the wordsor the language on the page.Solutions – Get a list that includes foreign keywords.Black Listing is very effective. This method matches the Internetaddress being accessed against a list of known bad sites. However, theeffectiveness depends on the quality of the lists you are using.

Pros – Stops over 90% of the unwanted sites. Cons – If the list is not kept up-to-date then it becomes less effective.Ways Around It – Connecting to another computer that is not on the blacklist and using it’s Internet connection to view web sites. Searching for pictures using a common image search engine. Many search engines likeimages.google.com will store thumbnail copies of images on the Internet.Someone looking for pornography could use a search engine that is not onthe black list to find small pictures. If they were to click on the picture to thengo to the link they would most likely be blocked.Solutions – Make sure the black list includes search engines likeimages.google.com that store thumbnail image previews. Then switch tousing a safe search engine like www.family-source.com

Real-time Content Analysis is usually used with a white and black list. Ifa web site is not on the white list (Good Sites) or the black list (Bad Sites)then a computer quickly looks at the web site before it lets you look at it.The computer tries to figure out what type of web site it is. If it can figureit out then access will be granted if it’s a good site and denied if it is bad. Pros – Blocks many of the new unseen sites that are added every day.Cons – It may make a wrong choice as to the content of the web site. Ways Around It – This method is the hardest one to get around. People willtry to use the same tactics that are used in the “Black List” method, but withless success. Also if a bad web site is miss judged by the computer then itwill allow the web site.Solutions – The same type of solutions used in the “Black List” method canbe used here. Another solution is to use a filtering system that keeps ahistory of visited sites. Then browse through this list every week or so to seewere people are going. Keep in mind that you don’t want to rely on thehistory that is kept in the web browser. This history can be cleared out orchanged.

Different Implementations of Filtering Systems and ProgramsHere we will go over the filtering systems. These are the actual programsor computers that do the filtering. The filtering systems will use some orall of the filtering methods shown above.Client Side FilteringClient side filtering relies on the computer that the user is using to accessthe Internet. The user installs a program on their computer. There aremany of these types of filtering programs available. Pros – Can start filtering today. The user does not need to switch Internetproviders. User has many options.Cons – Relies on software and settings installed on the users computer.Can greatly slow users Internet connection. This is because it relies on thepower and speed of your computer, so making filtering decisions can taketime. May need to be installed on every computer.Because the filtering happens on the same computer that is used to accessthe Internet there are ways around this filtering. There are programs that canbe installed to bypass the filter. Also, settings can be changed on thecomputer to bypass the filter.

ISP Proxy Filter With this system, you sets up a safe gateway to the Internet (a proxy).This proxy will access the Internet and give users only the safe pages.The ISP gives a customer a proxy server address that they put into theirweb browser settings. When this proxy address is set the user will accessthe Internet via the safe proxy server. It is also best to install software onthe computer that makes it hard to change the browsers proxy settings.Pros – It is very fast. The ISP’s fast servers are doing the filtering. Set upand configuring is simpler to installing the client side filtering programs.Cons – If the proxy settings are removed from your computer then thefiltering is bypassed. Also, a new browser can be installed that will bypassthe proxy server.Power

NOC Solution – ISP Forced Proxy with Firewall This system uses a proxy server like the above example but the setting toredirect Internet traffic to the proxy is on the ISP’s servers. If filtering isadded an account then all Internet traffic is forced to use the proxy. We are also able to block other types of Internet, like file sharing and chatrooms. This is done using the firewall option in our WISP Billing System.We create a unique firewall for each user. Not only will this block otherunwanted Internet services it will also block many computer viruses.A log of the web sites visited is created. This log is kept on your servers.Users can then review these logs to see what is being accessed.All of this is done on your servers, this means there are no settings on theusers computer that can be changed to get around the Internet filtering. When you implement PowerNOC’s WISP Billing System you are able tosecure the Internet in a way that is effective. You can create a filtering system that can not be bypassed.

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