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The computer they prefer!

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> English > Documentation > Advanced tools > Parental controls

Parental controls

November 2010 — last update October 2013

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Since version 2010-11, DoudouLinux provides a tool for parental controls whose role is to provide more security to parents. Right now it is made of a smart web page access filter. We believe that for an environment dedicated to children, this is the minimum to provide; thereafter, we plan to implement optional tools in order to limit daily hours of use of DoudouLinux or even the daily use duration. This would then ease conformation to a reasonable computer use, if this topic is one of your preoccupations [1].

Note: we do not pretend that our web page filtering tool is perfect and anyway we cannot guaranty that no “naughty” site will ever be displayed. Thus, this does not replace a minimum of vigilance by parents or a framing discussion with children about the few Internet dangers. The goal is more to not have to watch your children all the time, than to produce a totally cleaned Internet, a task which is impossible to achieve, whatever some people may say! Recall that one of the DoudouLinux goals is to have children feel comfortable with computers, which may quickly become a failure if parents have to watch their actions all the time.

Web page filtering

Warning: web page filtering is known to be reliable for English, French and Russian, and known as alpha version for Galician, Greek, Romanian, Serbian, Ukrainian, and probably some other languages, eg. Persian.

Web page filtering is based on DansGuardian. This software includes both a system of list of sites known to be safe or on the opposite targeting a public awareness, and a system of real-time page content analysis. Site lists can allow or reject pages coming from sites whose reputation is largely known as good or as bad. Content analysis consists in searching some words or expressions known to be “naughty”. A global page naughtiness is evaluated using a score associated to each word or expression. This way a page can be rejected before being shown to children.

Rejecting a DuckDuckGo search with the word “sex”

The screen capture above shows that a Google search with the word sex leads to a rejected page thanks to a systematic analysis of the actual content of the requested page. We let you check that this request leads to a list of pornographic sites, and that DoudouLinux does not block most Google requests.

Therefore, we have decided to concentrate on page content analysis for DoudouLinux rather than providing good and bad web site lists. The reasons for this choice are that the Internet is incredibly wide, making the creation and maintenance of lists an enormous work, but also because we have studied some black lists of sites said to be “naughty”. This study showed that black lists essentially contain sites that are no longer accessible or whose content has become safe again. It seems indeed that black lists contain essentially sites that were pirated one day but have then been restored or deleted. This makes us think that the only good solution is true content filtering as advertised by DansGuardian, ie. filtering that really analyzes the page contents and is not limited to looking at the page origin on the Internet.

Questions about web page filtering

Can web filtering be bypassed?

The DoudouLinux system design does not allow to access web pages without passing through page content filtering. Of course specialists may know how to restore a system without filtering but this requires changing the system network routing table from the console: this should give you immediate trust!

Can peer-to-peer and instant messaging be filtered too?

No, content filtering only analyzes web pages. If your child would be doing peer-to-peer downloading or instant messaging (chat), DansGuardian would not be able to do anything because these services do not rely upon web pages. However, in DoudouLinux it is not possible to do anything else but web on the Internet because the other tools are not installed [2]. Although an instant messaging client, Empathy, is available in DoudouLinux, it is configured to be only able to discuss on a local network, not on the Internet. This makes us believe that DoudouLinux is secured for the whole Internet and not only web pages.

Are downloaded files scanned for viruses?

No. This feature is disabled because this would require that DoudouLinux embed an antivirus software and its tools for upgrading signatures. As DoudouLinux is not targeted by malware and is basically a read-only system, we have decided that such feature is not necessary.

What kind of content is rejected?

Right now only filtering on pornographic terms is activated. We still need to translate terms of other categories in order to increase the web filtering operating field.

How can you imagine that children go to pornographic sites?

Just because of mistakes! Suppose they are having fun with friends and type “funny” words to be searched on the Internet. They could then get into pornographic sites… We really do not want that DoudouLinux may put them in such situation.

How to know what caused a page to be rejected?

You just need to click on the text “show details” in the page that informs you that the request was rejected. You will find information about the category and the language that triggered rejection as well as the list of words that modified the page score. You have to know that the score weights the page naughtiness and that, in the current DoudouLinux configuration, it should remain below 50 to not cause page rejection.

Are websites on non standard ports filtered too?

No, websites that are not configured as the standard says [3] are not filtered at all. We do not believe that this may be required for the moment because search engines are normally indexing only sites that are using the standard configuration. So this should not be possible to get into one of these sites by mistake, even after a search engine request.


[1] Which is generally impossible to setup on gaming consoles or TV sets.

[2] Unless required software get installed, but this requires actions in the system console, which should not be for children neither!

[3] This means that they are using a port different from port 80 to provide their pages.

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