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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hello Andres,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">N.B. Please take my answer with a huge grain of salt.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">The google images search returns image results (thumbnails) as inline base 64 encoded images in the CSS. Selectively blocking them with any URL redirector will
not work. It is possible to completely block google images but I assume this is not the way to follow for a school where a lot of pupil projects need access to the image search results.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Our current recommend the strategy for blocking explicit search results for schools are (please note you must be doing SSL decryption for this to work!):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- enforce Safe Search for Google. In this way proxy adds some special parameter to URL and some HTTP header to all outgoing requests to google servers asking
it to show only safe images. Unfortunately this sometime misses quite offensive images as no safe search is safe enough.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- add keyword filtering to filter results of image search as it also contains some textual description of images and their original URLs that greatly improves
detection rate. Some possible overblocking definitely will occur.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">- add image tone detection filtering to the mix (works only for JPEGs for now and higly experimental) :(<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">In order to do that you need to integrate a content scanning server with your Squid – as possible variant consider taking a look at what we develop exactly for
this purpose (search google for qlproxy ICAP – please note it is a commercial product).
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Other choices are DansGuardian as parent proxy and SquidGuard/ufdbGuard/other redirectors.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I hope some other members of the list can explain how to do what your require with these.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Rafael<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> squid-users [mailto:squid-users-bounces@lists.squid-cache.org]
<b>On Behalf Of </b>Andres Granados<br>
<b>Sent:</b> Monday, May 18, 2015 7:50 PM<br>
<b>To:</b> squid-users@lists.squid-cache.org<br>
<b>Subject:</b> [squid-users] block inappropriate images of google<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">hello!<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">I need help on how to block pornographic images of google, I was trying different options and still do not succeed, try: http_reply_access with request_header_add, and even with a configuration
dns, I think is to request_header_add the best, though not it has worked for me, I hope your help, is to implement a school, thanks!<o:p></o:p></span></p>
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