Tools, Technology and Internet Filtering

Tools, Technology and Internet Filtering

Internet filtering is good, it can be bad and sometimes it is real ugly. Read on to find out what you need to know, including how to bypass it.

Internet Filtering For Dummies

Internet filtering, yet another one of those techie buzzwords that sounds like a good thing, but do you really know what it is? Filtering, filters, are usually a good thing. Filters remove unwanted items from a larger matrix of what is wanted, leaving a cleaner, purer, version of what came before. The dictionary definition reads like this, to pass (liquid, gas, air, sound, light) through a device to remove unwanted material. Synonyms include sieve, strain, clarify, purify and refine so there really is no fault in thinking well of Internet filtering software, Internet filter routers and web filtering software is a good thing. The sad reality is quite the opposite. Internet filtering is one of the many ugly faces, unseen and largely unheard of, Internet censorship.

  • Internet Censorship is any form of control or suppression of what can be posted, viewed, transmitted or shared on the Internet. It exits in some form in nearly all countries and is vigorously practiced in some. Censoring ranges from simple monitoring of emails and traffic all the way through complete restriction of access such as is found in North Korea. In Cuba, if certain words or phrases are typed into a terminal at one of the tightly controlled cyber cafes the device will automatically shut down. Typically, censorship is an unwanted blockage of content although there are many times when individuals, groups or sects may choose to censor themselves.

Now, don’t get me wrong. There are lots, and I mean a lot, of very good and positive uses for web filtering software but those are not what I’m talking about. To be clear, good uses include parental controls of home Internet access, preventing children from Internet abuses, in libraries and schools and filtering content in the work place. I know, it isn’t great when your work prevents you from going on social media or buying tickets to that awesome concert but face it, you are at work and shouldn’t be doing that kind of stuff anyway. Bad uses of filtering software occurs when ISPs, censors or governments use them as part of an Internet blocking campaign.

  • The first filtering technology was intended for use at home, in schools and in libraries. The application of the technology was such that it soon became common place in businesses as well, fulfilling the dual purpose of keeping employees on task and protecting the local network from outside attacks. Since then the use of filter technology has spread across the Internet.

The difference between good and bad filtering, in many ways, is in the scope of what is being filtered and for who the filtering is being done. On a small scale, such as in the home or work environment, the use is intended for the protection of young minds and corporate assets be it time or devices. On the larger scale, when it comes to countries actively filtering content en masse, the practice becomes oppressive and malicious.

  • When would someone ever want to use web filtering against themselves? When it is used as part of an Internet security scheme to block out websites, content and traffic that is deemed harmful or may contain virus or malware. Protection provided is incomplete and should not be used as a stand alone method of securing your devices.

There are three main categories of filtering techniques; host based, server-side and content filtering at the ISP level. Host based filtering is when a system administrator installs filtering software on the local network and its devices. This is the type most often used in the home and office settings. Server-side filtering is used by larger businesses and other organizations at the gateway level. This software enables filtering of traffic as it enters the local area network giving a more complete protection. Filtering at the ISP level is the top-level method and a service now being offered by many Internet Service Providers. This technology enables businesses to utilize third party filtering services, or for governments to have tight control over web access.

Some Common Types of Internet Content Filtering Are:

Search Engine

Most if not all search engines in use by the average web surfer come with ready to use content filters installed. They can be set to filter content returned in search results but are easily bypassed, all you have to do is go directly to the website in question.

Browser based

Browser based filters are the easiest to deploy and offer the least amount of additional safety features. They are third party browser extensions downloaded from the web and operating directly on your devices.


E-mail filters are used to monitor and control email traffic. The filters can be used to target both the origination location of the emails and the content within, specifically attachments and executable files.

Client Side

Client Side filters are those purchased from a vendor and then installed directly onto devices in need. Examples include home and office web nanny type software.

Content Limited ISPs

Content limited ISPs, or filtered ISPs, offer only limited access to the Internet that can provide the most additional protection available by filtering. This is most often the type of control used by governmental agencies to restrict or censor access to the Internet.

Network Based

Network based filtering is applied at the transport or application layer and can be used in both an outgoing and incoming basis. Incoming traffic can be filtered to prevent harmful websites and malware from accessing the network, outgoing traffic can be monitored to prevent loss of data and intellectual property.

How Internet Filtering Works? What is internet content filtering and internet filtering software? Le VPN

Tools And Technology For Internet Filtering

A very comprehensive review of tools and technology for Internet filtering is outlined by Murdoch and Anderson (2008) and ranges from technical filtering to domain deregistration and denial-of- service attacks. In addition, they also briefly discuss surveillance and non-technical censorship methods. Murdoch and Anderson (2008) articulate the following Internet content filtering mechanisms:

  • TCP/IP header filtering: With this method, the censor’s router can inspect the Internet Protocol [IP] address and port number of the destination. If the destination is found to be on a blacklist, the connection is dropped or redirected to a page indicating that access to the destination is denied.
  • TCP/IP content filtering: This is a similar method to header filtering except that the censor’s router inspects the packet contents for any patterns or keywords that may be blacklisted. The focus is not on content, but rather on where packets are going to or coming from.
  • Domain Name Server (DNS) Tampering: Normally, domain name servers are accessed by user computers to retrieve the corresponding IP address of a given domain. Through domain name server tampering, domain name resolution could fail as the router could send back an erroneous response that does not contain the right IP address, hence the connection fails.
  • Hyper Text Transfer Protocol (HTTP) Proxy Filtering: In some cases, users are forced to use HTTP proxies that are assigned for accessing the Internet. Those proxies may be the only way to reach the Internet and hence they can monitor all traffic that goes through them. Such a method is more powerful than TCP/IP header and DNS filtering.
  • Hybrid TCP/IP and HTTP Proxy filtering: Because using HTTP Proxy Filtering is often demanding, a solution was devised to use only HTTP Proxy filtering for a list of IP addresses known to have prohibited content. If any of those IP addresses is accessed, traffic is redirected to a transparent HTTP proxy, which inspects the transferred stream and 
filters any banned content.
  • Denial-of-Service (DoS) attacks: Denial-of-service attacks can be launched on the host 
server. Such attacks are usually done by having a large number of computers requesting service from a particular server and hence, overwhelming it with too much traffic which causes the server and its connection to stall.
  • Server takedown: Through legal, extra-legal or pressure methods, a company hosting a specific server could take it down and disconnect it from the Internet. The owner of the server may be able to transfer the server’s contents, however – provided that a backup copy exists – to another hosting company within hours.
  • Surveillance: Constant technical monitoring through logging transfers between the host and the Internet user. If banned content is found in the transferred stream, actions – legal or extra-legal – could be taken against the user, the host or both. Such acts could trigger a sense of fear, causing the host to refrain from publishing such content and causing the user to hesitate from accessing it.
  • Social techniques: This includes the requirement to show photo identification (ID) before using public computers at libraries or Internet cafés; social or religious norms that force Internet users to avoid opening particular content are another form of social censorship. Families that place the computer in the living room to enable monitoring of their children’s use of the Internet is another example of a social technique of censorship.

How Internet Filtering Works

Internet filtering works in a number of ways, each company using its own proprietary method. That being said, the general way in which filtering works is like this. A filtering company such as Norton Online Family, NetNanny, Cyber Patrol or Parental Internet Filter will develop a system of categories that all websites will be judged against. The criteria could be things like trigger words in the content, IP addresses or other digital markers found on data packets streaming across the web. The category and ranking system is then used to build profiles like Children, Adult or Work. Profiles can come pre-installed with the software or be manually created by the system admin or parent.

  • An Internet filtering profile like Children might include things like sex, pornography, politics, hate, graphic and other tags. These tags trigger the filter, which will block all websites that have been categorized as such. Along with the filters restrictions, a profile like Children might also include a time setting which allows Internet access at only certain times of the day, or for a specific period.
  • Content Labeling – Content Labeling is a self-imposed method of rating a websites content begun in the mid 1990’s. An organization that is now part of the Family Online Safety Institute developed a rating system in which webmasters answered a few questions about their content in order to generate a short synopsis web filtering companies could use to help categorize websites.

An added benefit for network administrators and parents is the ability to see what kind of traffic is being blocked and who has requested it. The information can then be used to discipline the employee or child in question. When it comes to purchasing a filter they are designed for specific uses such as Business, Library & School and Home/Office.

Despite the many benefits of filtering there are times when the system fails. In some cases websites that have not yet been categorized or are too new to have been indexed will slip through. This is not usually a big problem but does offer the odd chance for a kid to some too much skin, or for an employee to waste a little too much time. Another time in which they fail is when content is miss-categorized and blocked without cause. Take for example a health article that might be mislabeled as pornography. This is a minor irritation only though, an administrator password is usually all it takes to bypass content restrictions.

The legality and moral questions imposed by the use of content filters are being argued to this day. On the one hand, control of improper, erroneous and offensive content is something to be desired. On the other, any form of suppression, regardless the intended good, has repercussions that can affect the freedoms of people across the planet. The US Supreme Court, on more than one occasion, has ruled in favor of free speech and against government or public censorship of the web.

VPN protocols | VPN security | Le VPN | secure VPN

Bypassing Internet Filtering Technology

At this point there are at least issues with Internet filtering technology, and they are not too closely related. The first has to do with using filter technology as a method of Internet Security, it’s not a great one. The second to do with the rampant use of filtering technology around the world, specifically when talking about countries that actively and heavily censor Internet use. The good news, believe it or not, is that bypassing these two issues is very, very easy. Even better, the solution for each is the solution for both, that is, their solution is one and the same: VPN. The unintended benefit is that a VPN will probably get you past a work or family imposed filter too, especially if it is installed on the gateway or firewall.

VPN, virtual private network, is the most advanced form of Internet security available today and one that is underutilized by the average web surfer. As a technology, VPN has been around for more than 30 years. As a viable source of Internet security for the average consumer, only a few years. The technology is a blending of two security protocols, one coming from the private sector and the other from the very people who created the Internet, the US government. It was first intended as a means of safely connecting remote users to a home network but its application and deployment come with a host of unintended, and very useful, consequences.

One of these is to bypass content filtering software on a variety of levels. The way it does this is the same way it provides security, by creating untraceable undetectable undecipherable connections. The short explanation is this: VPNs work from within enabled devices to encrypt and re-packet the data payloads, effectively hiding all identifying markers, and send them across the web using dedicated servers. The tunnels as they are called make it impossible for filter programs to detect your traffic much less ID it for censoring purposes. The security benefit is simple, if no one can detect your Internet connections then no one knows you’re on the Internet and if no one knows you’re on the Internet then they can’t target you for scams, fraud, data theft, hacking or malware. The bottom line, VPN fills in all the gaps left by antivirus software, firewalls and filters with the added bonus of completing your Internet security scheme.

Le VPN is the leading provider of VPN technology for the retail market with solutions for individuals, small businesses and families. Their network of over 700 dedicated servers in 100+ locations support 3 protocols and any device or operating system. The need for VPN is clear, the choice is clear, why wait, get Le VPN before it’s too late.

*Article updated on August 31st, 2018.*



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Written by Vuk Mujović @VukMujovic

Vuk Mujović is the founder of MacTíre Consulting, an analyst, data management expert, and a long-term writer on all things business & tech. He authored blogs, articles, and opinion pieces aimed to help both companies and individuals achieve growth without compromising their security. Vuk is a regular guest author to Le VPN Blog since January 2018, where he gives his expert opinion on the topics related to cybersecurity, privacy, online freedom, and personal data protection. He also often shares his tips and best practices in relation to internet security and digital safety of private individuals and small businesses, including some additional applications of using a VPN service.

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