Internet filter
An Internet filter is a type of internet censorship that restricts or controls the content an Internet user is capable to access, especially when utilized to restrict material delivered over the Internet via the Web, Email, or other means. Such restrictions can be applied at various levels: a government can attempt to apply them nationwide, or they can, for example, be applied by an Internet service provider to its clients, by an employer to its personnel, by a school to its students, by a library to its visitors, by a parent to a child's computer, or by an individual user to their own computers. The motive is often to prevent access to content which the computer's owner or other authorities may consider objectionable. When imposed without the consent of the user, content control can be characterised as a form of internet censorship. Some filter software includes time control functions that empowers parents to set the amount of time that child may spend accessing the Internet or playing games or other computer activities.
Terminology
The term "content control" is used on occasion by CNN, Playboy magazine, the San Francisco Chronicle, and The New York Times. However, several other terms, including "content filtering software", "web content filter", "filtering proxy servers", "secure web gateways", "censorware", "content security and control", "web filtering software", "content-censoring software", and "content-blocking software", are often used. "Nannyware" has also been used in both product marketing and by the media. Industry research company Gartner uses "secure web gateway" to describe the market segment.Companies that make products that selectively block Web sites do not refer to these products as censorware, and prefer terms such as "Internet filter" or "URL Filter"; in the specialized case of software specifically designed to allow parents to monitor and restrict the access of their children, "parental control software" is also used. Some products log all sites that a user accesses and rates them based on content type for reporting to an "accountability partner" of the person's choosing, and the term accountability software is used. Internet filters, parental control software, and/or accountability software may also be combined into one product.
Those critical of such software, however, use the term "censorware" freely: consider the Censorware Project, for example. The use of the term "censorware" in editorials criticizing makers of such software is widespread and covers many different varieties and applications: Xeni Jardin used the term in a 9 March 2006 editorial in The New York Times, when discussing the use of American-made filtering software to suppress content in China; in the same month a high school student used the term to discuss the deployment of such software in his school district.
In general, outside of editorial pages as described above, traditional newspapers do not use the term "censorware" in their reporting, preferring instead to use less overtly controversial terms such as "content filter", "content control", or "web filtering"; The New York Times and The Wall Street Journal both appear to follow this practice. On the other hand, Web-based newspapers such as CNET use the term in both editorial and journalistic contexts, for example "Windows Live to Get Censorware."
Types of filtering
Filters can be implemented in many different ways: by software on a personal computer, via network infrastructure such as proxy servers, DNS servers, or firewalls that provide Internet access. No solution provides complete coverage, so most companies deploy a mix of technologies to achieve the proper content control in line with their policies.Browser based filters
E-mail filters
Client-side filters
Content-limited (or filtered) ISPs
Network-based filtering
DNS-based filtering
Search-engine filters
Parental controls
Reasons for filtering
The Internet does not intrinsically provide content blocking, and therefore there is much content on the Internet that is considered unsuitable for children, given that much content is given certifications as suitable for adults only, e.g. 18-rated games and movies.Internet service providers that block material containing pornography, or controversial religious, political, or news-related content en route are often utilized by parents who do not permit their children to access content not conforming to their personal beliefs. Content filtering software can, however, also be used to block malware and other content that is or contains hostile, intrusive, or annoying material including adware, spam, computer viruses, worms, trojan horses, and spyware.
Most content control software is marketed to organizations or parents. It is, however, also marketed on occasion to facilitate self-censorship, for example by people struggling with addictions to online pornography, gambling, chat rooms, etc. Self-censorship software may also be utilised by some in order to avoid viewing content they consider immoral, inappropriate, or simply distracting. A number of accountability software products are marketed as self-censorship or accountability software. These are often promoted by religious media and at religious gatherings.
Technology
Content filtering technology exists in two major forms: application gateway or packet inspection. For HTTP access the application gateway is called a web-proxy or just a proxy. Such web-proxies can inspect both the initial request and the returned web page using arbitrarily complex rules and will not return any part of the page to the requester until a decision is made. In addition they can make substitutions in whole or for any part of the returned result. Packet inspection filters do not initially interfere with the connection to the server but inspect the data in the connection as it goes past, at some point the filter may decide that the connection is to be filtered and it will then disconnect it by injecting a TCP-Reset or similar faked packet. The two techniques can be used together with the packet filter monitoring a link until it sees an HTTP connection starting to an IP address that has content that needs filtering. The packet filter then redirects the connection to the web-proxy which can perform detailed filtering on the website without having to pass through all unfiltered connections. This combination is quite popular because it can significantly reduce the cost of the system.There are constraints to IP level packet-filtering, as it may result in rendering all web content associated with a particular IP address inaccessible. This may result in the unintentional blocking of legitimate sites that share the same IP address or domain. For instance, university websites commonly employ multiple domains under one IP address. Moreover, IP level packet-filtering can be surpassed by using a distinct IP address for certain content while still being linked to the same domain or server.
Gateway-based content control software may be more difficult to bypass than desktop software as the user does not have physical access to the filtering device. However, many of the techniques in the Bypassing filters section still work.
Content labeling
Content labeling may be considered another form of content-control software. In 1994, the Internet Content Rating Association — now part of the Family Online Safety Institute — developed a content rating system for online content providers. Using an online questionnaire a webmaster describes the nature of their web content. A small file is generated that contains a condensed, computer readable digest of this description that can then be used by content filtering software to block or allow that site.ICRA labels come in a variety of formats. These include the World Wide Web Consortium's Resource Description Framework as well as Platform for Internet Content Selection labels used by Microsoft's Internet Explorer Content Advisor.
ICRA labels are an example of self-labeling. Similarly, in 2006 the Association of Sites Advocating Child Protection initiated the Restricted to Adults self-labeling initiative. ASACP members were concerned that various forms of legislation being proposed in the United States were going to have the effect of forcing adult companies to label their content. The RTA label, unlike ICRA labels, does not require a webmaster to fill out a questionnaire or sign up to use. Like ICRA the RTA label is free. Both labels are recognized by a wide variety of content-control software.
The Voluntary Content Rating system was devised by Solid Oak Software for their CYBERsitter filtering software, as an alternative to the PICS system, which some critics deemed too complex. It employs HTML metadata tags embedded within web page documents to specify the type of content contained in the document. Only two levels are specified, mature and adult, making the specification extremely simple.
By country
Australia
The Australian Internet Safety Advisory Body has information about "practical advice on Internet safety, parental control and filters for the protection of children, students and families" that also includes public libraries.NetAlert, the software made available free of charge by the Australian government, was allegedly cracked by a 16-year-old student, Tom Wood, less than a week after its release in August 2007. Wood supposedly bypassed the $84 million filter in about half an hour to highlight problems with the government's approach to Internet content filtering.
The Australian Government has introduced legislation that requires ISPs to "restrict access to age restricted content either hosted in Australia or provided from Australia" that was due to commence from 20 January 2008, known as Cleanfeed.
Cleanfeed is a proposed mandatory ISP level content filtration system. It was proposed by the Beazley led Australian Labor Party opposition in a 2006 press release, with the intention of protecting children who were vulnerable due to claimed parental computer illiteracy. It was announced on 31 December 2007 as a policy to be implemented by the Rudd ALP government, and initial tests in Tasmania have produced a 2008 report. Cleanfeed is funded in the current budget, and is moving towards an Expression of Interest for live testing with ISPs in 2008. Public opposition and criticism have emerged, led by the EFA and gaining irregular mainstream media attention, with a majority of Australians reportedly "strongly against" its implementation. Criticisms include its expense, inaccuracy and the fact that it will be compulsory, which can be seen as an intrusion on free speech rights. Another major criticism point has been that although the filter is claimed to stop certain materials, the underground rings dealing in such materials will not be affected. The filter might also provide a false sense of security for parents, who might supervise children less while using the Internet, achieving the exact opposite effect. Cleanfeed is a responsibility of Senator Conroy's portfolio.