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+ <div class="SECT1">
+ <h1 class="SECT1"><a name="MISC" id="MISC">4. Miscellaneous</a></h1>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="SLOWSME" id="SLOWSME">4.1. How much does Privoxy slow my browsing down? This has to
+ add extra time to browsing.</a></h3>
+ <p>How much of an impact depends on many things, including the CPU of the host system, how aggressive the
+ configuration is, which specific actions are being triggered, the size of the page, the bandwidth of the
+ connection, etc.</p>
+ <p>Overall, it should not slow you down any in real terms, and may actually help speed things up since ads,
+ banners and other junk are not typically being retrieved and displayed. The actual processing time required by
+ <span class="APPLICATION">Privoxy</span> itself for each page, is relatively small in the overall scheme of
+ things, and happens very quickly. This is typically more than offset by time saved not downloading and rendering
+ ad images and other junk content (if ad blocking is being used).</p>
+ <p><span class="QUOTE">"Filtering"</span> content via the <tt class="LITERAL"><a href=
+ "../user-manual/actions-file.html#FILTER" target="_top">filter</a></tt> or <tt class="LITERAL"><a href=
+ "../user-manual/actions-file.html#DEANIMATE-GIFS" target="_top">deanimate-gifs</a></tt> actions may cause a
+ perceived slowdown, since the entire document needs to be buffered before displaying. And on very large
+ documents, filtering may have some measurable impact. How much depends on the page size, the actual definition of
+ the filter(s), etc. See below. Most other actions have little to no impact on speed.</p>
+ <p>Also, when filtering is enabled but zlib support isn't available, compression is often disabled (see <a href=
+ "../user-manual/actions-file.html#PREVENT-COMPRESSION" target="_top">prevent-compression</a>). This can have an
+ impact on speed as well, although it's probably smaller than you might think. Again, the page size, etc. will
+ determine how much of an impact.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="LOADINGTIMES" id="LOADINGTIMES">4.2. I notice considerable delays in page requests.
+ What's wrong?</a></h3>
+ <p>If you use any <tt class="LITERAL"><a href="../user-manual/actions-file.html#FILTER" target=
+ "_top">filter</a></tt> action, such as filtering banners by size, web-bugs etc, or the <tt class=
+ "LITERAL"><a href="../user-manual/actions-file.html#DEANIMATE-GIFS" target="_top">deanimate-gifs</a></tt> action,
+ the entire document must be loaded into memory in order for the filtering mechanism to work, and nothing is sent
+ to the browser during this time.</p>
+ <p>The loading time typically does not really change much in real numbers, but the feeling is different, because
+ most browsers are able to start rendering incomplete content, giving the user a feeling of "it works". This
+ effect is more noticeable on slower dialup connections. Extremely large documents may have some impact on the
+ time to load the page where there is filtering being done. But overall, the difference should be very minimal. If
+ there is a big impact, then probably some other situation is contributing (like anti-virus software).</p>
+ <p>Filtering is automatically disabled for inappropriate MIME types. But note that if the web server mis-reports
+ the MIME type, then content that should not be filtered, could be. <span class="APPLICATION">Privoxy</span> only
+ knows how to differentiate filterable content because of the MIME type as reported by the server, or because of
+ some configuration setting that enables/disables filtering.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="CONFIGURL" id="CONFIGURL">4.3. What are "http://config.privoxy.org/" and
+ "http://p.p/"?</a></h3>
+ <p><a href="http://config.privoxy.org/" target="_top">http://config.privoxy.org/</a> is the address of
+ <span class="APPLICATION">Privoxy</span>'s built-in user interface, and <a href="http://p.p/" target=
+ "_top">http://p.p/</a> is a shortcut for it.</p>
+ <p>Since <span class="APPLICATION">Privoxy</span> sits between your web browser and the Internet, it can simply
+ intercept requests for these addresses and answer them with its built-in <span class="QUOTE">"web
+ server"</span>.</p>
+ <p>This also makes for a good test for your browser configuration: If entering the URL <a href=
+ "http://config.privoxy.org/" target="_top">http://config.privoxy.org/</a> takes you to a page saying <span class=
+ "QUOTE">"This is Privoxy ..."</span>, everything is OK. If you get a page saying <span class="QUOTE">"Privoxy is
+ not working"</span> instead, then your browser didn't use <span class="APPLICATION">Privoxy</span> for the
+ request, hence it could not be intercepted, and you have accessed the <span class="emphasis"><i class=
+ "EMPHASIS">real</i></span> web site at config.privoxy.org.</p>
+ <p>Note that config.privoxy.org resolves to a public IP address. If you use config.privoxy.org as ping or
+ traceroute target you will reach the system on the Internet (Privoxy can't intercept ICMP requests). If you want
+ to ping the system Privoxy runs on, you should use its IP address or local DNS name (if it has got one).</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="NEWADS" id="NEWADS">4.4. How can I submit new ads, or report problems?</a></h3>
+ <p>Please see the <a href="contact.html">Contact section</a> for various ways to interact with the
+ developers.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="NEWADS2" id="NEWADS2">4.5. If I do submit missed ads, will they be included in future
+ updates?</a></h3>
+ <p>Whether such submissions are eventually included in the <tt class="FILENAME">default.action</tt> configuration
+ file depends on how significant the issue is. We of course want to address any potential problem with major,
+ high-profile sites such as <i class="CITETITLE">Google</i>, <i class="CITETITLE">Yahoo</i>, etc. Any site with
+ global or regional reach, has a good chance of being a candidate. But at the other end of the spectrum are any
+ number of smaller, low-profile sites such as for local clubs or schools. Since their reach and impact are much
+ less, they are best handled by inclusion in the user's <tt class="FILENAME">user.action</tt>, and thus would be
+ unlikely to be included.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="NOONECARES" id="NOONECARES">4.6. Why doesn't anyone answer my support
+ request?</a></h3>
+ <p>Rest assured that it has been read and considered. Why it is not answered, could be for various reasons,
+ including no one has a good answer for it, no one has had time to yet investigate it thoroughly, it has been
+ reported numerous times already, or because not enough information was provided to help us help you. Your efforts
+ are not wasted, and we do appreciate them.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="IP" id="IP">4.7. How can I hide my IP address?</a></h3>
+ <p>If you run both the browser and <span class="APPLICATION">Privoxy</span> locally, you cannot hide your IP
+ address with <span class="APPLICATION">Privoxy</span> or ultimately any other software alone. The server needs to
+ know your IP address so that it knows where to send the responses back.</p>
+ <p>There are many publicly usable "anonymous" proxies out there, which provide a further level of indirection
+ between you and the web server.</p>
+ <p>However, these proxies are called "anonymous" because you don't need to authenticate, not because they would
+ offer any real anonymity. Most of them will log your IP address and make it available to the authorities in case
+ you violate the law of the country they run in. In fact you can't even rule out that some of them only exist to
+ *collect* information on (those suspicious) people with a more than average preference for privacy.</p>
+ <p>If you want to hide your IP address from most adversaries, you should consider chaining <span class=
+ "APPLICATION">Privoxy</span> with <a href="https://www.torproject.org/" target="_top">Tor</a>. The configuration
+ details can be found in <a href="#TOR" target="_top">How do I use <span class="APPLICATION">Privoxy</span>
+ together with <span class="APPLICATION">Tor</span> section</a> just below.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="ANONFORSURE" id="ANONFORSURE">4.8. Can Privoxy guarantee I am anonymous?</a></h3>
+ <p>No. Your chances of remaining anonymous are improved, but unless you <a href="#TOR" target="_top">chain
+ <span class="APPLICATION">Privoxy</span> with <span class="APPLICATION">Tor</span></a> or a similar proxy and
+ know what you're doing when it comes to configuring the rest of your system, you should assume that everything
+ you do on the Web can be traced back to you.</p>
+ <p><span class="APPLICATION">Privoxy</span> can remove various information about you, and allows <span class=
+ "emphasis"><i class="EMPHASIS">you</i></span> more freedom to decide which sites you can trust, and what details
+ you want to reveal. But it neither hides your IP address, nor can it guarantee that the rest of the system
+ behaves correctly. There are several possibilities how a web sites can find out who you are, even if you are
+ using a strict <span class="APPLICATION">Privoxy</span> configuration and chained it with <span class=
+ "APPLICATION">Tor</span>.</p>
+ <p>Most of <span class="APPLICATION">Privoxy's</span> privacy-enhancing features can be easily subverted by an
+ insecure browser configuration, therefore you should use a browser that can be configured to only execute code
+ from trusted sites, and be careful which sites you trust. For example there is no point in having <span class=
+ "APPLICATION">Privoxy</span> modify the User-Agent header, if websites can get all the information they want
+ through JavaScript, ActiveX, Flash, Java etc.</p>
+ <p>A few browsers disclose the user's email address in certain situations, such as when transferring a file by
+ FTP. <span class="APPLICATION">Privoxy</span> does not filter FTP. If you need this feature, or are concerned
+ about the mail handler of your browser disclosing your email address, you might consider products such as
+ <span class="APPLICATION">NSClean</span>.</p>
+ <p>Browsers available only as binaries could use non-standard headers to give out any information they can have
+ access to: see the manufacturer's license agreement. It's impossible to anticipate and prevent every breach of
+ privacy that might occur. The professionally paranoid prefer browsers available as source code, because
+ anticipating their behavior is easier. Trust the source, Luke!</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="PROXYTEST" id="PROXYTEST">4.9. A test site says I am not using a Proxy.</a></h3>
+ <p>Good! Actually, they are probably testing for some other kinds of proxies. Hiding yourself completely would
+ require additional steps.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="TOR" id="TOR">4.10. How do I use Privoxy together with Tor?</a></h3>
+ <p>Before you configure <span class="APPLICATION">Privoxy</span> to use <a href="https://www.torproject.org/"
+ target="_top">Tor</a>, please follow the <i class="CITETITLE">User Manual</i> chapters <a href=
+ "../user-manual/installation.html" target="_top">2. Installation</a> and <a href="../user-manual/startup.html"
+ target="_top">5. Startup</a> to make sure <span class="APPLICATION">Privoxy</span> itself is setup correctly.</p>
+ <p>If it is, refer to <a href="https://www.torproject.org/documentation.html" target="_top">Tor's extensive
+ documentation</a> to learn how to install <span class="APPLICATION">Tor</span>, and make sure <span class=
+ "APPLICATION">Tor</span>'s logfile says that <span class="QUOTE">"Tor has successfully opened a circuit"</span>
+ and it <span class="QUOTE">"looks like client functionality is working"</span>.</p>
+ <p>If either <span class="APPLICATION">Tor</span> or <span class="APPLICATION">Privoxy</span> isn't working,
+ their combination most likely will neither. Testing them on their own will also help you to direct problem
+ reports to the right audience. If <span class="APPLICATION">Privoxy</span> isn't working, don't bother the
+ <span class="APPLICATION">Tor</span> developers. If <span class="APPLICATION">Tor</span> isn't working, don't
+ send bug reports to the <span class="APPLICATION">Privoxy</span> Team.</p>
+ <p>If you verified that <span class="APPLICATION">Privoxy</span> and <span class="APPLICATION">Tor</span> are
+ working, it is time to connect them. As far as <span class="APPLICATION">Privoxy</span> is concerned,
+ <span class="APPLICATION">Tor</span> is just another proxy that can be reached by socks4, socks4a and socks5.
+ Most likely you are interested in <span class="APPLICATION">Tor</span> to increase your anonymity level,
+ therefore you should use socks5, to make sure DNS requests are done through <span class="APPLICATION">Tor</span>
+ and thus invisible to your local network. Using socks4a would work too, but with socks5 you get more precise
+ error messages.</p>
+ <p><span class="APPLICATION">Privoxy's</span> <a href="../user-manual/config.html" target="_top">main
+ configuration file</a> is already prepared for <span class="APPLICATION">Tor</span>, if you are using a default
+ <span class="APPLICATION">Tor</span> configuration and run it on the same system as <span class=
+ "APPLICATION">Privoxy</span>, you just have to edit the <a href="../user-manual/config.html#FORWARDING" target=
+ "_top">forwarding section</a> and uncomment the line:</p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
- <th colspan="3" align="center">
- Privoxy Frequently Asked Questions
- </th>
+ <td>
+ <pre class="SCREEN"> # forward-socks5t / 127.0.0.1:9050 .</pre>
+ </td>
</tr>
+ </table>
+ <p>Note that if you got Tor through one of the bundles, you may have to change the port from 9050 to 9150 (or
+ even another one). For details, please check the documentation on the <a href="https://torproject.org/" target=
+ "_top">Tor website</a>.</p>
+ <p>This is enough to reach the Internet, but additionally you might want to uncomment the following forward
+ rules, to make sure your local network is still reachable through Privoxy:</p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
- <td width="10%" align="left" valign="bottom">
- <a href="configuration.html" accesskey="P">Prev</a>
+ <td>
+ <pre class="SCREEN"> # forward 192.168.*.*/ .
+ # forward 10.*.*.*/ .
+ # forward 127.*.*.*/ .</pre>
</td>
- <td width="80%" align="center" valign="bottom">
+ </tr>
+ </table>
+ <p>Unencrypted connections to systems in these address ranges will be as (un)secure as the local network is, but
+ the alternative is that your browser can't reach the network at all. Then again, that may actually be desired and
+ if you don't know for sure that your browser has to be able to reach the local network, there's no reason to
+ allow it.</p>
+ <p>If you want your browser to be able to reach servers in your local network by using their names, you will need
+ additional exceptions that look like this:</p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN"> # forward localhost/ .</pre>
</td>
- <td width="10%" align="right" valign="bottom">
- <a href="trouble.html" accesskey="N">Next</a>
+ </tr>
+ </table>
+ <p>Save the modified configuration file and open <a href="http://config.privoxy.org/show-status" target=
+ "_top">http://config.privoxy.org/show-status</a> in your browser, confirm that <span class=
+ "APPLICATION">Privoxy</span> has reloaded its configuration and that there are no other forward lines, unless you
+ know that you need them. If everything looks good, refer to <a href=
+ "https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#IsMyConnectionPrivate" target="_top">Tor Faq 4.2</a>
+ to learn how to verify that you are really using <span class="APPLICATION">Tor</span>.</p>
+ <p>Afterward, please take the time to at least skim through the rest of <span class="APPLICATION">Tor's</span>
+ documentation. Make sure you understand what <span class="APPLICATION">Tor</span> does, why it is no replacement
+ for application level security, and why you probably don't want to use it for unencrypted logins.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="SITEBREAK" id="SITEBREAK">4.11. Might some things break because header information or
+ content is being altered?</a></h3>
+ <p>Definitely. It is common for sites to use browser type, browser version, HTTP header content, and various
+ other techniques in order to dynamically decide what to display and how to display it. What you see, and what I
+ see, might be very different. There are many, many ways that this can be handled, so having hard and fast rules,
+ is tricky.</p>
+ <p>The <span class="QUOTE">"User-Agent"</span> is sometimes used in this way to identify the browser, and adjust
+ content accordingly.</p>
+ <p>Also, different browsers use different encodings of non-English characters, certain web servers convert pages
+ on-the-fly according to the User Agent header. Giving a <span class="QUOTE">"User Agent"</span> with the wrong
+ operating system or browser manufacturer causes some sites in these languages to be garbled; Surfers to Eastern
+ European sites should change it to something closer. And then some page access counters work by looking at the
+ <span class="QUOTE">"Referer"</span> header; they may fail or break if unavailable. The weather maps of
+ Intellicast have been blocked by their server when no <span class="QUOTE">"Referer"</span> or cookie is provided,
+ is another example. (But you can forge both headers without giving information away). There are many other ways
+ things can go wrong when trying to fool a web server. The results of which could inadvertently cause pages to
+ load incorrectly, partially, or even not at all. And there may be no obvious clues as to just what went wrong, or
+ why. Nowhere will there be a message that says <span class="QUOTE">"<span class="emphasis"><i class=
+ "EMPHASIS">Turn off <tt class="LITERAL">fast-redirects</tt> or else!</i></span> "</span></p>
+ <p>Similar thoughts apply to modifying JavaScript, and, to a lesser degree, HTML elements.</p>
+ <p>If you have problems with a site, you will have to adjust your configuration accordingly. Cookies are probably
+ the most likely adjustment that may be required, but by no means the only one.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="CACHING" id="CACHING">4.12. Can Privoxy act as a <span class="QUOTE">"caching"</span>
+ proxy to speed up web browsing?</a></h3>
+ <p>No, it does not have this ability at all. You want something like <a href="http://www.squid-cache.org/"
+ target="_top">Squid</a> or <a href="https://www.irif.fr/~jch//software/polipo/" target="_top">Polipo</a> for
+ this. And, yes, before you ask, <span class="APPLICATION">Privoxy</span> can co-exist with other kinds of proxies
+ like <span class="APPLICATION">Squid</span>. See the <a href="../user-manual/config.html#FORWARDING" target=
+ "_top">forwarding chapter</a> in the <a href="../user-manual/index.html" target="_top">user manual</a> for
+ details.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="FIREWALL" id="FIREWALL">4.13. What about as a firewall? Can Privoxy protect
+ me?</a></h3>
+ <p>Not in the way you mean, or in the way some firewall vendors claim they can. <span class=
+ "APPLICATION">Privoxy</span> can help protect your privacy, but can't protect your system from intrusion
+ attempts. It is, of course, perfectly possible to use <span class="emphasis"><i class=
+ "EMPHASIS">both</i></span>.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="WASTED" id="WASTED">4.14. I have large empty spaces / a checkerboard pattern now where
+ ads used to be. Why?</a></h3>
+ <p>It is technically possible to eliminate banners and ads in a way that frees their allocated page space. This
+ could easily be done by blocking with <span class="APPLICATION">Privoxy's</span> filters, and eliminating the
+ <span class="emphasis"><i class="EMPHASIS">entire</i></span> image references from the HTML page source.</p>
+ <p>But, this would consume considerably more CPU resources (IOW, slow things down), would likely destroy the
+ layout of some web pages which rely on the banners utilizing a certain amount of page space, and might fail in
+ other cases, where the screen space is reserved (e.g. by HTML tables for instance). Also, making ads and banners
+ disappear without any trace complicates troubleshooting, and would sooner or later be problematic.</p>
+ <p>The better alternative is to instead let them stay, and block the resulting requests for the banners
+ themselves as is now the case. This leaves either empty space, or the familiar checkerboard pattern.</p>
+ <p>So the developers won't support this in the default configuration, but you can of course define appropriate
+ filters yourself to achieve this.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="SSL" id="SSL">4.15. How can Privoxy filter Secure (HTTPS) URLs?</a></h3>
+ <p>If you enable <a href="../user-manual/actions-file.html#HTTPS-INSPECTION" target="_top">https-inspection</a>
+ <span class="APPLICATION">Privoxy</span> will impersonate the destination server and can thus filter encrypted
+ requests and responses as well.</p>
+ <p>Without <a href="../user-manual/actions-file.html#HTTPS-INSPECTION" target="_top">https-inspection</a> secure
+ HTTP connections are encrypted SSL sessions between your browser and the secure site, and there is little that
+ <span class="APPLICATION">Privoxy</span> can do but hand the raw gibberish data though from one end to the other
+ unprocessed.</p>
+ <p>The only exception to this is blocking by host patterns, as the client needs to tell <span class=
+ "APPLICATION">Privoxy</span> the name of the remote server, so that <span class="APPLICATION">Privoxy</span> can
+ establish the connection. If that name matches a host-only pattern, the connection will be blocked.</p>
+ <p>As far as ad blocking is concerned, this is less of a restriction than it may seem, since ad sources are often
+ identifiable by the host name, and often the banners to be placed in an encrypted page come unencrypted
+ nonetheless for efficiency reasons, which exposes them to the full power of <span class=
+ "APPLICATION">Privoxy</span>'s ad blocking.</p>
+ <p><span class="QUOTE">"Content cookies"</span> (those that are embedded in the actual HTML or JS page content,
+ see <tt class="LITERAL"><a href="../user-manual/actions-file.html#FILTER-CONTENT-COOKIES" target=
+ "_top">filter{content-cookies}</a></tt>), in an SSL transaction will be impossible to block under these
+ conditions. Fortunately, this does not seem to be a very common scenario since most cookies come by traditional
+ means.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="HTTP2" id="HTTP2">4.16. Does Privoxy support HTTP/2?</a></h3>
+ <p>Privoxy currently doesn't parse HTTP/2 but applications can tunnel HTTP/2 through Privoxy if Privoxy is
+ configured to allow CONNECT requests (default) which are also used for HTTPS.</p>
+ <p>Adding HTTP/2 support is on the <a href=
+ "https://www.privoxy.org/gitweb/?p=privoxy.git;a=blob_plain;f=TODO;hb=HEAD" target="_top">TODO</a> list but
+ currently nobody is known to work on it.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="SECURE" id="SECURE">4.17. Privoxy runs as a <span class="QUOTE">"server"</span>. How
+ secure is it? Do I need to take any special precautions?</a></h3>
+ <p>On Unix-like systems, <span class="APPLICATION">Privoxy</span> can run as a non-privileged user, which is how
+ we recommend it be run. Also, by default <span class="APPLICATION">Privoxy</span> listens to requests from
+ <span class="QUOTE">"localhost"</span> only.</p>
+ <p>The server aspect of <span class="APPLICATION">Privoxy</span> is not itself directly exposed to the Internet
+ in this configuration. If you want to have <span class="APPLICATION">Privoxy</span> serve as a LAN proxy, this
+ will have to be opened up to allow for LAN requests. In this case, we'd recommend you specify only the LAN
+ gateway address, e.g. 192.168.1.1, in the main <span class="APPLICATION">Privoxy</span> configuration file and
+ check all <a href="../user-manual/config.html#ACCESS-CONTROL" target="_top">access control and security
+ options</a>. All LAN hosts can then use this as their proxy address in the browser proxy configuration, but
+ <span class="APPLICATION">Privoxy</span> will not listen on any external interfaces. ACLs can be defined in
+ addition, and using a firewall is always good too. Better safe than sorry.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="TURNOFF" id="TURNOFF">4.18. Can I temporarily disable Privoxy?</a></h3>
+ <p><span class="APPLICATION">Privoxy</span> doesn't have a transparent proxy mode, but you can toggle off
+ blocking and content filtering.</p>
+ <p>The easiest way to do that is to point your browser to the remote toggle URL: <a href=
+ "http://config.privoxy.org/toggle" target="_top">http://config.privoxy.org/toggle</a>.</p>
+ <p>See the <a href="../user-manual/appendix.html#BOOKMARKLETS" target="_top">Bookmarklets section</a> of the
+ <i class="CITETITLE">User Manual</i> for an easy way to access this feature. Note that this is a feature that may
+ need to be enabled in the main <tt class="FILENAME">config</tt> file.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="REALLYOFF" id="REALLYOFF">4.19. When <span class="QUOTE">"disabled"</span> is Privoxy
+ totally out of the picture?</a></h3>
+ <p>No, this just means all optional filtering and actions are disabled. <span class="APPLICATION">Privoxy</span>
+ is still acting as a proxy, but just doing less of the things that <span class="APPLICATION">Privoxy</span> would
+ normally be expected to do. It is still a <span class="QUOTE">"middle-man"</span> in the interaction between your
+ browser and web sites. See below to bypass the proxy.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="TURNOFF2" id="TURNOFF2">4.20. How can I tell Privoxy to totally ignore certain
+ sites?</a></h3>
+ <p>Bypassing a proxy, or proxying based on arbitrary criteria, is purely a browser configuration issue, not a
+ <span class="APPLICATION">Privoxy</span> issue. Modern browsers typically do have settings for not proxying
+ certain sites. Check your browser's help files.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="CRUNCH" id="CRUNCH">4.21. My logs show Privoxy <span class="QUOTE">"crunches"</span>
+ ads, but also its own internal CGI pages. What is a <span class="QUOTE">"crunch"</span>?</a></h3>
+ <p>A <span class="QUOTE">"crunch"</span> means <span class="APPLICATION">Privoxy</span> intercepted <span class=
+ "emphasis"><i class="EMPHASIS">something</i></span>, nothing more. Often this is indeed ads or banners, but
+ <span class="APPLICATION">Privoxy</span> uses the same mechanism for trapping requests for its own internal
+ pages. For instance, a request for <span class="APPLICATION">Privoxy's</span> configuration page at: <a href=
+ "http://config.privoxy.org" target="_top">http://config.privoxy.org</a>, is intercepted (i.e. it does not go out
+ to the 'net), and the familiar CGI configuration is returned to the browser, and the log consequently will show a
+ <span class="QUOTE">"crunch"</span>.</p>
+ <p>Since version 3.0.7, Privoxy will also log the crunch reason. If you are using an older version you might want
+ to upgrade.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="DOWNLOADS" id="DOWNLOADS">4.22. Can Privoxy affect files that I download from a
+ webserver? FTP server?</a></h3>
+ <p>From the webserver's perspective, there is no difference between viewing a document (i.e. a page), and
+ downloading a file. The same is true of <span class="APPLICATION">Privoxy</span>. If there is a match for a
+ <tt class="LITERAL"><a href="../user-manual/actions-file.html#BLOCK" target="_top">block</a></tt> pattern, it
+ will still be blocked, and of course this is obvious.</p>
+ <p>Filtering is potentially more of a concern since the results are not always so obvious, and the effects of
+ filtering are there whether the file is simply viewed, or downloaded. And potentially whether the content is some
+ obnoxious advertisement, or Mr. Jimmy's latest/greatest source code jewel. Of course, one of these presumably is
+ <span class="QUOTE">"bad"</span> content that we don't want, and the other is <span class="QUOTE">"good"</span>
+ content that we do want. <span class="APPLICATION">Privoxy</span> is blind to the differences, and can only
+ distinguish <span class="QUOTE">"good from bad"</span> by the configuration parameters <span class=
+ "emphasis"><i class="EMPHASIS">we</i></span> give it.</p>
+ <p><span class="APPLICATION">Privoxy</span> knows the differences in files according to the <span class=
+ "QUOTE">"Content Type"</span> as reported by the webserver. If this is reported accurately (e.g. <span class=
+ "QUOTE">"application/zip"</span> for a zip archive), then <span class="APPLICATION">Privoxy</span> knows to
+ ignore these where appropriate. <span class="APPLICATION">Privoxy</span> potentially can filter HTML as well as
+ plain text documents, subject to configuration parameters of course. Also, documents that are of an unknown type
+ (generally assumed to be <span class="QUOTE">"text/plain"</span>) can be filtered, as will those that might be
+ incorrectly reported by the webserver. If such a file is a downloaded file that is intended to be saved to disk,
+ then any content that might have been altered by filtering, will be saved too, for these (probably rare)
+ cases.</p>
+ <p>Note that versions later than 3.0.2 do NOT filter document types reported as <span class=
+ "QUOTE">"text/plain"</span>. Prior to this, <span class="APPLICATION">Privoxy</span> did filter this document
+ type.</p>
+ <p>In short, filtering is <span class="QUOTE">"ON"</span> if a) the content type as reported by the webserver is
+ appropriate <span class="emphasis"><i class="EMPHASIS">and</i></span> b) the configuration allows it (or at least
+ does not disallow it). That's it. There is no magic cookie anywhere to say this is <span class=
+ "QUOTE">"good"</span> and this is <span class="QUOTE">"bad"</span>. It's the configuration that lets it all
+ happen or not.</p>
+ <p>If you download text files, you probably do not want these to be filtered, particularly if the content is
+ source code, or other critical content. Source code sometimes might be mistaken for Javascript (i.e. the kind
+ that might open a pop-up window). It is recommended to turn off filtering for download sites (particularly if the
+ content may be plain text files and you are using version 3.0.2 or earlier) in your <tt class=
+ "FILENAME">user.action</tt> file. And also, for any site or page where making <span class="emphasis"><i class=
+ "EMPHASIS">any</i></span> changes at all to the content is to be avoided.</p>
+ <p><span class="APPLICATION">Privoxy</span> does not do FTP at all, only HTTP and HTTPS (SSL) protocols.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="DOWNLOADS2" id="DOWNLOADS2">4.23. I just downloaded a Perl script, and Privoxy altered
+ it! Yikes, what is wrong!</a></h3>
+ <p>Please read above.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="HOSTSFILE" id="HOSTSFILE">4.24. Should I continue to use a <span class=
+ "QUOTE">"HOSTS"</span> file for ad-blocking?</a></h3>
+ <p>One time-tested technique to defeat common ads is to trick the local DNS system by giving a phony IP address
+ for the ad generator in the local <tt class="FILENAME">HOSTS</tt> file, typically using <tt class=
+ "LITERAL">127.0.0.1</tt>, aka <tt class="LITERAL">localhost</tt>. This effectively blocks the ad.</p>
+ <p>There is no reason to use this technique in conjunction with <span class="APPLICATION">Privoxy</span>.
+ <span class="APPLICATION">Privoxy</span> does essentially the same thing, much more elegantly and with much more
+ flexibility. A large <tt class="FILENAME">HOSTS</tt> file, in fact, not only duplicates effort, but may get in
+ the way and seriously slow down your system. It is recommended to remove such entries from your <tt class=
+ "FILENAME">HOSTS</tt> file. If you think your hosts list is neglected by <span class=
+ "APPLICATION">Privoxy's</span> configuration, consider adding your list to your <tt class=
+ "FILENAME">user.action</tt> file:</p>
+ <table border="0" bgcolor="#E0E0E0" width="100%">
+ <tr>
+ <td>
+ <pre class="SCREEN"> { +block }
+ www.ad.example1.com
+ ad.example2.com
+ ads.galore.example.com
+ etc.example.com</pre>
</td>
</tr>
</table>
- <hr align="LEFT" width="100%">
</div>
- <div class="SECT1">
- <h1 class="SECT1">
- <a name="MISC">4. Miscellaneous</a>
- </h1>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="SLOWSME">4.1. How much does Privoxy slow my browsing down?
- This has to add extra time to browsing.</a>
- </h3>
- <p>
- How much of an impact depends on many things, including the CPU of
- the host system, how aggressive the configuration is, which
- specific actions are being triggered, the size of the page, the
- bandwidth of the connection, etc.
- </p>
- <p>
- Overall, it should not slow you down any in real terms, and may
- actually help speed things up since ads, banners and other junk are
- not typically being retrieved and displayed. The actual processing
- time required by <span class="APPLICATION">Privoxy</span> itself
- for each page, is relatively small in the overall scheme of things,
- and happens very quickly. This is typically more than offset by
- time saved not downloading and rendering ad images and other junk
- content (if ad blocking is being used).
- </p>
- <p>
- <span class="QUOTE">"Filtering"</span> content via the <tt class=
- "LITERAL"><a href="../user-manual/actions-file.html#FILTER" target=
- "_top">filter</a></tt> or <tt class="LITERAL"><a href=
- "../user-manual/actions-file.html#DEANIMATE-GIFS" target=
- "_top">deanimate-gifs</a></tt> actions may cause a perceived
- slowdown, since the entire document needs to be buffered before
- displaying. And on very large documents, filtering may have some
- measurable impact. How much depends on the page size, the actual
- definition of the filter(s), etc. See below. Most other actions
- have little to no impact on speed.
- </p>
- <p>
- Also, when filtering is enabled but zlib support isn't available,
- compression is often disabled (see <a href=
- "../user-manual/actions-file.html#PREVENT-COMPRESSION" target=
- "_top">prevent-compression</a>). This can have an impact on speed
- as well, although it's probably smaller than you might think.
- Again, the page size, etc. will determine how much of an impact.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="LOADINGTIMES">4.2. I notice considerable delays in page
- requests. What's wrong?</a>
- </h3>
- <p>
- If you use any <tt class="LITERAL"><a href=
- "../user-manual/actions-file.html#FILTER" target=
- "_top">filter</a></tt> action, such as filtering banners by size,
- web-bugs etc, or the <tt class="LITERAL"><a href=
- "../user-manual/actions-file.html#DEANIMATE-GIFS" target=
- "_top">deanimate-gifs</a></tt> action, the entire document must be
- loaded into memory in order for the filtering mechanism to work,
- and nothing is sent to the browser during this time.
- </p>
- <p>
- The loading time typically does not really change much in real
- numbers, but the feeling is different, because most browsers are
- able to start rendering incomplete content, giving the user a
- feeling of "it works". This effect is more noticeable on slower
- dialup connections. Extremely large documents may have some impact
- on the time to load the page where there is filtering being done.
- But overall, the difference should be very minimal. If there is a
- big impact, then probably some other situation is contributing
- (like anti-virus software).
- </p>
- <p>
- Filtering is automatically disabled for inappropriate MIME types.
- But note that if the web server mis-reports the MIME type, then
- content that should not be filtered, could be. <span class=
- "APPLICATION">Privoxy</span> only knows how to differentiate
- filterable content because of the MIME type as reported by the
- server, or because of some configuration setting that
- enables/disables filtering.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="CONFIGURL">4.3. What are "http://config.privoxy.org/" and
- "http://p.p/"?</a>
- </h3>
- <p>
- <a href="http://config.privoxy.org/" target=
- "_top">http://config.privoxy.org/</a> is the address of <span
- class="APPLICATION">Privoxy</span>'s built-in user interface, and
- <a href="http://p.p/" target="_top">http://p.p/</a> is a shortcut
- for it.
- </p>
- <p>
- Since <span class="APPLICATION">Privoxy</span> sits between your
- web browser and the Internet, it can simply intercept requests for
- these addresses and answer them with its built-in <span class=
- "QUOTE">"web server"</span>.
- </p>
- <p>
- This also makes for a good test for your browser configuration: If
- entering the URL <a href="http://config.privoxy.org/" target=
- "_top">http://config.privoxy.org/</a> takes you to a page saying
- <span class="QUOTE">"This is Privoxy ..."</span>, everything is OK.
- If you get a page saying <span class="QUOTE">"Privoxy is not
- working"</span> instead, then your browser didn't use <span class=
- "APPLICATION">Privoxy</span> for the request, hence it could not be
- intercepted, and you have accessed the <span class="emphasis"><i
- class="EMPHASIS">real</i></span> web site at config.privoxy.org.
- </p>
- <p>
- Note that config.privoxy.org resolves to a public IP address. If
- you use config.privoxy.org as ping or traceroute target you will
- reach the system on the Internet (Privoxy can't intercept ICMP
- requests). If you want to ping the system Privoxy runs on, you
- should use its IP address or local DNS name (if it has got one).
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="NEWADS">4.4. How can I submit new ads, or report
- problems?</a>
- </h3>
- <p>
- Please see the <a href="contact.html">Contact section</a> for
- various ways to interact with the developers.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="NEWADS2">4.5. If I do submit missed ads, will they be
- included in future updates?</a>
- </h3>
- <p>
- Whether such submissions are eventually included in the <tt class=
- "FILENAME">default.action</tt> configuration file depends on how
- significant the issue is. We of course want to address any
- potential problem with major, high-profile sites such as <i class=
- "CITETITLE">Google</i>, <i class="CITETITLE">Yahoo</i>, etc. Any
- site with global or regional reach, has a good chance of being a
- candidate. But at the other end of the spectrum are any number of
- smaller, low-profile sites such as for local clubs or schools.
- Since their reach and impact are much less, they are best handled
- by inclusion in the user's <tt class="FILENAME">user.action</tt>,
- and thus would be unlikely to be included.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="NOONECARES">4.6. Why doesn't anyone answer my support
- request?</a>
- </h3>
- <p>
- Rest assured that it has been read and considered. Why it is not
- answered, could be for various reasons, including no one has a good
- answer for it, no one has had time to yet investigate it
- thoroughly, it has been reported numerous times already, or because
- not enough information was provided to help us help you. Your
- efforts are not wasted, and we do appreciate them.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="IP">4.7. How can I hide my IP address?</a>
- </h3>
- <p>
- If you run both the browser and <span class=
- "APPLICATION">Privoxy</span> locally, you cannot hide your IP
- address with <span class="APPLICATION">Privoxy</span> or ultimately
- any other software alone. The server needs to know your IP address
- so that it knows where to send the responses back.
- </p>
- <p>
- There are many publicly usable "anonymous" proxies out there, which
- provide a further level of indirection between you and the web
- server.
- </p>
- <p>
- However, these proxies are called "anonymous" because you don't
- need to authenticate, not because they would offer any real
- anonymity. Most of them will log your IP address and make it
- available to the authorities in case you violate the law of the
- country they run in. In fact you can't even rule out that some of
- them only exist to *collect* information on (those suspicious)
- people with a more than average preference for privacy.
- </p>
- <p>
- If you want to hide your IP address from most adversaries, you
- should consider chaining <span class="APPLICATION">Privoxy</span>
- with <a href="https://www.torproject.org/" target="_top">Tor</a>.
- The configuration details can be found in <a href="#TOR" target=
- "_top">How do I use <span class="APPLICATION">Privoxy</span>
- together with <span class="APPLICATION">Tor</span> section</a> just
- below.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="ANONFORSURE">4.8. Can Privoxy guarantee I am
- anonymous?</a>
- </h3>
- <p>
- No. Your chances of remaining anonymous are improved, but unless
- you <a href="#TOR" target="_top">chain <span class=
- "APPLICATION">Privoxy</span> with <span class=
- "APPLICATION">Tor</span></a> or a similar proxy and know what
- you're doing when it comes to configuring the rest of your system,
- you should assume that everything you do on the Web can be traced
- back to you.
- </p>
- <p>
- <span class="APPLICATION">Privoxy</span> can remove various
- information about you, and allows <span class="emphasis"><i class=
- "EMPHASIS">you</i></span> more freedom to decide which sites you
- can trust, and what details you want to reveal. But it neither
- hides your IP address, nor can it guarantee that the rest of the
- system behaves correctly. There are several possibilities how a web
- sites can find out who you are, even if you are using a strict
- <span class="APPLICATION">Privoxy</span> configuration and chained
- it with <span class="APPLICATION">Tor</span>.
- </p>
- <p>
- Most of <span class="APPLICATION">Privoxy's</span>
- privacy-enhancing features can be easily subverted by an insecure
- browser configuration, therefore you should use a browser that can
- be configured to only execute code from trusted sites, and be
- careful which sites you trust. For example there is no point in
- having <span class="APPLICATION">Privoxy</span> modify the
- User-Agent header, if websites can get all the information they
- want through JavaScript, ActiveX, Flash, Java etc.
- </p>
- <p>
- A few browsers disclose the user's email address in certain
- situations, such as when transferring a file by FTP. <span class=
- "APPLICATION">Privoxy</span> does not filter FTP. If you need this
- feature, or are concerned about the mail handler of your browser
- disclosing your email address, you might consider products such as
- <span class="APPLICATION">NSClean</span>.
- </p>
- <p>
- Browsers available only as binaries could use non-standard headers
- to give out any information they can have access to: see the
- manufacturer's license agreement. It's impossible to anticipate and
- prevent every breach of privacy that might occur. The
- professionally paranoid prefer browsers available as source code,
- because anticipating their behavior is easier. Trust the source,
- Luke!
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="PROXYTEST">4.9. A test site says I am not using a
- Proxy.</a>
- </h3>
- <p>
- Good! Actually, they are probably testing for some other kinds of
- proxies. Hiding yourself completely would require additional steps.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="TOR">4.10. How do I use Privoxy together with Tor?</a>
- </h3>
- <p>
- Before you configure <span class="APPLICATION">Privoxy</span> to
- use <a href="https://www.torproject.org/" target="_top">Tor</a>,
- please follow the <i class="CITETITLE">User Manual</i> chapters <a
- href="../user-manual/installation.html" target="_top">2.
- Installation</a> and <a href="../user-manual/startup.html" target=
- "_top">5. Startup</a> to make sure <span class=
- "APPLICATION">Privoxy</span> itself is setup correctly.
- </p>
- <p>
- If it is, refer to <a href=
- "https://www.torproject.org/documentation.html" target="_top">Tor's
- extensive documentation</a> to learn how to install <span class=
- "APPLICATION">Tor</span>, and make sure <span class=
- "APPLICATION">Tor</span>'s logfile says that <span class=
- "QUOTE">"Tor has successfully opened a circuit"</span> and it <span
- class="QUOTE">"looks like client functionality is working"</span>.
- </p>
- <p>
- If either <span class="APPLICATION">Tor</span> or <span class=
- "APPLICATION">Privoxy</span> isn't working, their combination most
- likely will neither. Testing them on their own will also help you
- to direct problem reports to the right audience. If <span class=
- "APPLICATION">Privoxy</span> isn't working, don't bother the <span
- class="APPLICATION">Tor</span> developers. If <span class=
- "APPLICATION">Tor</span> isn't working, don't send bug reports to
- the <span class="APPLICATION">Privoxy</span> Team.
- </p>
- <p>
- If you verified that <span class="APPLICATION">Privoxy</span> and
- <span class="APPLICATION">Tor</span> are working, it is time to
- connect them. As far as <span class="APPLICATION">Privoxy</span> is
- concerned, <span class="APPLICATION">Tor</span> is just another
- proxy that can be reached by socks4, socks4a and socks5. Most
- likely you are interested in <span class="APPLICATION">Tor</span>
- to increase your anonymity level, therefore you should use socks5,
- to make sure DNS requests are done through <span class=
- "APPLICATION">Tor</span> and thus invisible to your local network.
- Using socks4a would work too, but with socks5 you get more precise
- error messages.
- </p>
- <p>
- <span class="APPLICATION">Privoxy's</span> <a href=
- "../user-manual/config.html" target="_top">main configuration
- file</a> is already prepared for <span class=
- "APPLICATION">Tor</span>, if you are using a default <span class=
- "APPLICATION">Tor</span> configuration and run it on the same
- system as <span class="APPLICATION">Privoxy</span>, you just have
- to edit the <a href="../user-manual/config.html#FORWARDING" target=
- "_top">forwarding section</a> and uncomment the line:
- </p>
- <p>
- </p>
- <table border="0" bgcolor="#E0E0E0" width="100%">
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="SEEALSO" id="SEEALSO">4.25. Where can I find more information about Privoxy and
+ related issues?</a></h3>
+ <p>Other references and sites of interest to <span class="APPLICATION">Privoxy</span> users:</p>
+ <table border="0">
+ <tbody>
<tr>
- <td>
-<pre class="SCREEN">
-# forward-socks5t / 127.0.0.1:9050 .
-</pre>
- </td>
+ <td><a href="https://www.privoxy.org/" target="_top">https://www.privoxy.org/</a>, the <span class=
+ "APPLICATION">Privoxy</span> Home page.</td>
</tr>
- </table>
-
- <p>
- Note that if you got Tor through one of the bundles, you may have
- to change the port from 9050 to 9150 (or even another one). For
- details, please check the documentation on the <a href=
- "https://torproject.org/" target="_top">Tor website</a>.
- </p>
- <p>
- This is enough to reach the Internet, but additionally you might
- want to uncomment the following forward rules, to make sure your
- local network is still reachable through Privoxy:
- </p>
- <p>
- </p>
- <table border="0" bgcolor="#E0E0E0" width="100%">
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
<tr>
- <td>
-<pre class="SCREEN">
-# forward 192.168.*.*/ .
-# forward 10.*.*.*/ .
-# forward 127.*.*.*/ .
-</pre>
- </td>
+ <td><a href="https://www.privoxy.org/faq/" target="_top">https://www.privoxy.org/faq/</a>, the <span class=
+ "APPLICATION">Privoxy</span> FAQ.</td>
</tr>
- </table>
-
- <p>
- Unencrypted connections to systems in these address ranges will be
- as (un)secure as the local network is, but the alternative is that
- your browser can't reach the network at all. Then again, that may
- actually be desired and if you don't know for sure that your
- browser has to be able to reach the local network, there's no
- reason to allow it.
- </p>
- <p>
- If you want your browser to be able to reach servers in your local
- network by using their names, you will need additional exceptions
- that look like this:
- </p>
- <p>
- </p>
- <table border="0" bgcolor="#E0E0E0" width="100%">
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
<tr>
- <td>
-<pre class="SCREEN">
-# forward localhost/ .
-</pre>
- </td>
+ <td><a href="https://www.privoxy.org/developer-manual/" target=
+ "_top">https://www.privoxy.org/developer-manual/</a>, the <span class="APPLICATION">Privoxy</span>
+ developer manual.</td>
</tr>
- </table>
-
- <p>
- Save the modified configuration file and open <a href=
- "http://config.privoxy.org/show-status" target=
- "_top">http://config.privoxy.org/show-status</a> in your browser,
- confirm that <span class="APPLICATION">Privoxy</span> has reloaded
- its configuration and that there are no other forward lines, unless
- you know that you need them. If everything looks good, refer to <a
- href=
- "https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#IsMyConnectionPrivate"
- target="_top">Tor Faq 4.2</a> to learn how to verify that you are
- really using <span class="APPLICATION">Tor</span>.
- </p>
- <p>
- Afterward, please take the time to at least skim through the rest
- of <span class="APPLICATION">Tor's</span> documentation. Make sure
- you understand what <span class="APPLICATION">Tor</span> does, why
- it is no replacement for application level security, and why you
- probably don't want to use it for unencrypted logins.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="SITEBREAK">4.11. Might some things break because header
- information or content is being altered?</a>
- </h3>
- <p>
- Definitely. It is common for sites to use browser type, browser
- version, HTTP header content, and various other techniques in order
- to dynamically decide what to display and how to display it. What
- you see, and what I see, might be very different. There are many,
- many ways that this can be handled, so having hard and fast rules,
- is tricky.
- </p>
- <p>
- The <span class="QUOTE">"User-Agent"</span> is sometimes used in
- this way to identify the browser, and adjust content accordingly.
- </p>
- <p>
- Also, different browsers use different encodings of non-English
- characters, certain web servers convert pages on-the-fly according
- to the User Agent header. Giving a <span class="QUOTE">"User
- Agent"</span> with the wrong operating system or browser
- manufacturer causes some sites in these languages to be garbled;
- Surfers to Eastern European sites should change it to something
- closer. And then some page access counters work by looking at the
- <span class="QUOTE">"Referer"</span> header; they may fail or break
- if unavailable. The weather maps of Intellicast have been blocked
- by their server when no <span class="QUOTE">"Referer"</span> or
- cookie is provided, is another example. (But you can forge both
- headers without giving information away). There are many other ways
- things can go wrong when trying to fool a web server. The results
- of which could inadvertently cause pages to load incorrectly,
- partially, or even not at all. And there may be no obvious clues as
- to just what went wrong, or why. Nowhere will there be a message
- that says <span class="QUOTE">"<span class="emphasis"><i class=
- "EMPHASIS">Turn off <tt class="LITERAL">fast-redirects</tt> or
- else!</i></span> "</span>
- </p>
- <p>
- Similar thoughts apply to modifying JavaScript, and, to a lesser
- degree, HTML elements.
- </p>
- <p>
- If you have problems with a site, you will have to adjust your
- configuration accordingly. Cookies are probably the most likely
- adjustment that may be required, but by no means the only one.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="CACHING">4.12. Can Privoxy act as a <span class=
- "QUOTE">"caching"</span> proxy to speed up web browsing?</a>
- </h3>
- <p>
- No, it does not have this ability at all. You want something like
- <a href="http://www.squid-cache.org/" target="_top">Squid</a> or <a
- href="http://www.pps.jussieu.fr/~jch/software/polipo/" target=
- "_top">Polipo</a> for this. And, yes, before you ask, <span class=
- "APPLICATION">Privoxy</span> can co-exist with other kinds of
- proxies like <span class="APPLICATION">Squid</span>. See the <a
- href="../user-manual/config.html#FORWARDING" target=
- "_top">forwarding chapter</a> in the <a href=
- "../user-manual/index.html" target="_top">user manual</a> for
- details.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="FIREWALL">4.13. What about as a firewall? Can Privoxy
- protect me?</a>
- </h3>
- <p>
- Not in the way you mean, or in the way some firewall vendors claim
- they can. <span class="APPLICATION">Privoxy</span> can help protect
- your privacy, but can't protect your system from intrusion
- attempts. It is, of course, perfectly possible to use <span class=
- "emphasis"><i class="EMPHASIS">both</i></span>.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="WASTED">4.14. I have large empty spaces / a checkerboard
- pattern now where ads used to be. Why?</a>
- </h3>
- <p>
- It is technically possible to eliminate banners and ads in a way
- that frees their allocated page space. This could easily be done by
- blocking with <span class="APPLICATION">Privoxy's</span> filters,
- and eliminating the <span class="emphasis"><i class=
- "EMPHASIS">entire</i></span> image references from the HTML page
- source.
- </p>
- <p>
- But, this would consume considerably more CPU resources (IOW, slow
- things down), would likely destroy the layout of some web pages
- which rely on the banners utilizing a certain amount of page space,
- and might fail in other cases, where the screen space is reserved
- (e.g. by HTML tables for instance). Also, making ads and banners
- disappear without any trace complicates troubleshooting, and would
- sooner or later be problematic.
- </p>
- <p>
- The better alternative is to instead let them stay, and block the
- resulting requests for the banners themselves as is now the case.
- This leaves either empty space, or the familiar checkerboard
- pattern.
- </p>
- <p>
- So the developers won't support this in the default configuration,
- but you can of course define appropriate filters yourself to
- achieve this.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="SSL">4.15. How can Privoxy filter Secure (HTTPS) URLs?</a>
- </h3>
- <p>
- Since secure HTTP connections are encrypted SSL sessions between
- your browser and the secure site, and are meant to be reliably
- <span class="emphasis"><i class="EMPHASIS">secure</i></span>, there
- is little that <span class="APPLICATION">Privoxy</span> can do but
- hand the raw gibberish data though from one end to the other
- unprocessed.
- </p>
- <p>
- The only exception to this is blocking by host patterns, as the
- client needs to tell <span class="APPLICATION">Privoxy</span> the
- name of the remote server, so that <span class=
- "APPLICATION">Privoxy</span> can establish the connection. If that
- name matches a host-only pattern, the connection will be blocked.
- </p>
- <p>
- As far as ad blocking is concerned, this is less of a restriction
- than it may seem, since ad sources are often identifiable by the
- host name, and often the banners to be placed in an encrypted page
- come unencrypted nonetheless for efficiency reasons, which exposes
- them to the full power of <span class=
- "APPLICATION">Privoxy</span>'s ad blocking.
- </p>
- <p>
- <span class="QUOTE">"Content cookies"</span> (those that are
- embedded in the actual HTML or JS page content, see <tt class=
- "LITERAL"><a href=
- "../user-manual/actions-file.html#FILTER-CONTENT-COOKIES" target=
- "_top">filter{content-cookies}</a></tt>), in an SSL transaction
- will be impossible to block under these conditions. Fortunately,
- this does not seem to be a very common scenario since most cookies
- come by traditional means.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="SECURE">4.16. Privoxy runs as a <span class=
- "QUOTE">"server"</span>. How secure is it? Do I need to take any
- special precautions?</a>
- </h3>
- <p>
- On Unix-like systems, <span class="APPLICATION">Privoxy</span> can
- run as a non-privileged user, which is how we recommend it be run.
- Also, by default <span class="APPLICATION">Privoxy</span> listens
- to requests from <span class="QUOTE">"localhost"</span> only.
- </p>
- <p>
- The server aspect of <span class="APPLICATION">Privoxy</span> is
- not itself directly exposed to the Internet in this configuration.
- If you want to have <span class="APPLICATION">Privoxy</span> serve
- as a LAN proxy, this will have to be opened up to allow for LAN
- requests. In this case, we'd recommend you specify only the LAN
- gateway address, e.g. 192.168.1.1, in the main <span class=
- "APPLICATION">Privoxy</span> configuration file and check all <a
- href="../user-manual/config.html#ACCESS-CONTROL" target=
- "_top">access control and security options</a>. All LAN hosts can
- then use this as their proxy address in the browser proxy
- configuration, but <span class="APPLICATION">Privoxy</span> will
- not listen on any external interfaces. ACLs can be defined in
- addition, and using a firewall is always good too. Better safe than
- sorry.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="TURNOFF">4.17. Can I temporarily disable Privoxy?</a>
- </h3>
- <p>
- <span class="APPLICATION">Privoxy</span> doesn't have a transparent
- proxy mode, but you can toggle off blocking and content filtering.
- </p>
- <p>
- The easiest way to do that is to point your browser to the remote
- toggle URL: <a href="http://config.privoxy.org/toggle" target=
- "_top">http://config.privoxy.org/toggle</a>.
- </p>
- <p>
- See the <a href="../user-manual/appendix.html#BOOKMARKLETS" target=
- "_top">Bookmarklets section</a> of the <i class="CITETITLE">User
- Manual</i> for an easy way to access this feature. Note that this
- is a feature that may need to be enabled in the main <tt class=
- "FILENAME">config</tt> file.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="REALLYOFF">4.18. When <span class=
- "QUOTE">"disabled"</span> is Privoxy totally out of the
- picture?</a>
- </h3>
- <p>
- No, this just means all optional filtering and actions are
- disabled. <span class="APPLICATION">Privoxy</span> is still acting
- as a proxy, but just doing less of the things that <span class=
- "APPLICATION">Privoxy</span> would normally be expected to do. It
- is still a <span class="QUOTE">"middle-man"</span> in the
- interaction between your browser and web sites. See below to bypass
- the proxy.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="TURNOFF2">4.19. How can I tell Privoxy to totally ignore
- certain sites?</a>
- </h3>
- <p>
- Bypassing a proxy, or proxying based on arbitrary criteria, is
- purely a browser configuration issue, not a <span class=
- "APPLICATION">Privoxy</span> issue. Modern browsers typically do
- have settings for not proxying certain sites. Check your browser's
- help files.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="CRUNCH">4.20. My logs show Privoxy <span class=
- "QUOTE">"crunches"</span> ads, but also its own internal CGI pages.
- What is a <span class="QUOTE">"crunch"</span>?</a>
- </h3>
- <p>
- A <span class="QUOTE">"crunch"</span> simply means <span class=
- "APPLICATION">Privoxy</span> intercepted <span class="emphasis"><i
- class="EMPHASIS">something</i></span>, nothing more. Often this is
- indeed ads or banners, but <span class="APPLICATION">Privoxy</span>
- uses the same mechanism for trapping requests for its own internal
- pages. For instance, a request for <span class=
- "APPLICATION">Privoxy's</span> configuration page at: <a href=
- "http://config.privoxy.org" target=
- "_top">http://config.privoxy.org</a>, is intercepted (i.e. it does
- not go out to the 'net), and the familiar CGI configuration is
- returned to the browser, and the log consequently will show a <span
- class="QUOTE">"crunch"</span>.
- </p>
- <p>
- Since version 3.0.7, Privoxy will also log the crunch reason. If
- you are using an older version you might want to upgrade.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="DOWNLOADS">4.21. Can Privoxy affect files that I download
- from a webserver? FTP server?</a>
- </h3>
- <p>
- From the webserver's perspective, there is no difference between
- viewing a document (i.e. a page), and downloading a file. The same
- is true of <span class="APPLICATION">Privoxy</span>. If there is a
- match for a <tt class="LITERAL"><a href=
- "../user-manual/actions-file.html#BLOCK" target=
- "_top">block</a></tt> pattern, it will still be blocked, and of
- course this is obvious.
- </p>
- <p>
- Filtering is potentially more of a concern since the results are
- not always so obvious, and the effects of filtering are there
- whether the file is simply viewed, or downloaded. And potentially
- whether the content is some obnoxious advertisement, or Mr. Jimmy's
- latest/greatest source code jewel. Of course, one of these
- presumably is <span class="QUOTE">"bad"</span> content that we
- don't want, and the other is <span class="QUOTE">"good"</span>
- content that we do want. <span class="APPLICATION">Privoxy</span>
- is blind to the differences, and can only distinguish <span class=
- "QUOTE">"good from bad"</span> by the configuration parameters
- <span class="emphasis"><i class="EMPHASIS">we</i></span> give it.
- </p>
- <p>
- <span class="APPLICATION">Privoxy</span> knows the differences in
- files according to the <span class="QUOTE">"Content Type"</span> as
- reported by the webserver. If this is reported accurately (e.g.
- <span class="QUOTE">"application/zip"</span> for a zip archive),
- then <span class="APPLICATION">Privoxy</span> knows to ignore these
- where appropriate. <span class="APPLICATION">Privoxy</span>
- potentially can filter HTML as well as plain text documents,
- subject to configuration parameters of course. Also, documents that
- are of an unknown type (generally assumed to be <span class=
- "QUOTE">"text/plain"</span>) can be filtered, as will those that
- might be incorrectly reported by the webserver. If such a file is a
- downloaded file that is intended to be saved to disk, then any
- content that might have been altered by filtering, will be saved
- too, for these (probably rare) cases.
- </p>
- <p>
- Note that versions later than 3.0.2 do NOT filter document types
- reported as <span class="QUOTE">"text/plain"</span>. Prior to this,
- <span class="APPLICATION">Privoxy</span> did filter this document
- type.
- </p>
- <p>
- In short, filtering is <span class="QUOTE">"ON"</span> if a) the
- content type as reported by the webserver is appropriate <span
- class="emphasis"><i class="EMPHASIS">and</i></span> b) the
- configuration allows it (or at least does not disallow it). That's
- it. There is no magic cookie anywhere to say this is <span class=
- "QUOTE">"good"</span> and this is <span class="QUOTE">"bad"</span>.
- It's the configuration that lets it all happen or not.
- </p>
- <p>
- If you download text files, you probably do not want these to be
- filtered, particularly if the content is source code, or other
- critical content. Source code sometimes might be mistaken for
- Javascript (i.e. the kind that might open a pop-up window). It is
- recommended to turn off filtering for download sites (particularly
- if the content may be plain text files and you are using version
- 3.0.2 or earlier) in your <tt class="FILENAME">user.action</tt>
- file. And also, for any site or page where making <span class=
- "emphasis"><i class="EMPHASIS">any</i></span> changes at all to the
- content is to be avoided.
- </p>
- <p>
- <span class="APPLICATION">Privoxy</span> does not do FTP at all,
- only HTTP and HTTPS (SSL) protocols.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="DOWNLOADS2">4.22. I just downloaded a Perl script, and
- Privoxy altered it! Yikes, what is wrong!</a>
- </h3>
- <p>
- Please read above.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="HOSTSFILE">4.23. Should I continue to use a <span class=
- "QUOTE">"HOSTS"</span> file for ad-blocking?</a>
- </h3>
- <p>
- One time-tested technique to defeat common ads is to trick the
- local DNS system by giving a phony IP address for the ad generator
- in the local <tt class="FILENAME">HOSTS</tt> file, typically using
- <tt class="LITERAL">127.0.0.1</tt>, aka <tt class=
- "LITERAL">localhost</tt>. This effectively blocks the ad.
- </p>
- <p>
- There is no reason to use this technique in conjunction with <span
- class="APPLICATION">Privoxy</span>. <span class=
- "APPLICATION">Privoxy</span> does essentially the same thing, much
- more elegantly and with much more flexibility. A large <tt class=
- "FILENAME">HOSTS</tt> file, in fact, not only duplicates effort,
- but may get in the way and seriously slow down your system. It is
- recommended to remove such entries from your <tt class=
- "FILENAME">HOSTS</tt> file. If you think your hosts list is
- neglected by <span class="APPLICATION">Privoxy's</span>
- configuration, consider adding your list to your <tt class=
- "FILENAME">user.action</tt> file:
- </p>
- <p>
- </p>
- <table border="0" bgcolor="#E0E0E0" width="100%">
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
<tr>
- <td>
-<pre class="SCREEN">
- { +block }
- www.ad.example1.com
- ad.example2.com
- ads.galore.example.com
- etc.example.com
-</pre>
- </td>
+ <td><a href="https://sourceforge.net/projects/ijbswa/" target=
+ "_top">https://sourceforge.net/projects/ijbswa/</a>, the Project Page for <span class=
+ "APPLICATION">Privoxy</span> on <a href="https://sourceforge.net" target="_top">SourceForge</a>.</td>
</tr>
- </table>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="SEEALSO">4.24. Where can I find more information about
- Privoxy and related issues?</a>
- </h3>
- <p>
- Other references and sites of interest to <span class=
- "APPLICATION">Privoxy</span> users:
- </p>
- <p>
- </p>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="https://www.privoxy.org/" target=
- "_top">https://www.privoxy.org/</a>, the <span class=
- "APPLICATION">Privoxy</span> Home page.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="https://www.privoxy.org/faq/" target=
- "_top">https://www.privoxy.org/faq/</a>, the <span class=
- "APPLICATION">Privoxy</span> FAQ.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="https://www.privoxy.org/developer-manual/" target=
- "_top">https://www.privoxy.org/developer-manual/</a>, the
- <span class="APPLICATION">Privoxy</span> developer manual.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="https://sourceforge.net/projects/ijbswa/" target=
- "_top">https://sourceforge.net/projects/ijbswa/</a>, the
- Project Page for <span class="APPLICATION">Privoxy</span> on
- <a href="http://sourceforge.net" target=
- "_top">SourceForge</a>.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="http://config.privoxy.org/" target=
- "_top">http://config.privoxy.org/</a>, the web-based user
- interface. <span class="APPLICATION">Privoxy</span> must be
- running for this to work. Shortcut: <a href="http://p.p/"
- target="_top">http://p.p/</a>
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href=
- "https://sourceforge.net/tracker/?group_id=11118&atid=460288"
- target=
- "_top">https://sourceforge.net/tracker/?group_id=11118&atid=460288</a>,
- to submit <span class="QUOTE">"misses"</span> and other
- configuration related suggestions to the developers.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="http://www.squid-cache.org/" target=
- "_top">http://www.squid-cache.org/</a>, a popular caching
- proxy, which is often used together with <span class=
- "APPLICATION">Privoxy</span>.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href=
- "http://www.pps.univ-paris-diderot.fr/~jch/software/polipo/"
- target=
- "_top">http://www.pps.univ-paris-diderot.fr/~jch/software/polipo/</a>,
- <span class="APPLICATION">Polipo</span> is a caching proxy
- with advanced features like pipelining, multiplexing and
- caching of partial instances. In many setups it can be used
- as <span class="APPLICATION">Squid</span> replacement.
- </td>
- </tr>
- </tbody>
- </table>
- <table border="0">
- <tbody>
- <tr>
- <td>
- <a href="https://www.torproject.org/" target=
- "_top">https://www.torproject.org/</a>, <span class=
- "APPLICATION">Tor</span> can help anonymize web browsing, web
- publishing, instant messaging, IRC, SSH, and other
- applications.
- </td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="MICROSUCK">4.25. I've noticed that Privoxy changes <span
- class="QUOTE">"Microsoft"</span> to <span class=
- "QUOTE">"MicroSuck"</span>! Why are you manipulating my
- browsing?</a>
- </h3>
- <p>
- We're not. The text substitutions that you are seeing are disabled
- in the default configuration as shipped. You have either manually
- activated the <span class="QUOTE">"<tt class=
- "LITERAL">fun</tt>"</span> filter which is clearly labeled <span
- class="QUOTE">"Text replacements for subversive browsing
- fun!"</span> or you are using an older Privoxy version and have
- implicitly activated it by choosing the <span class=
- "QUOTE">"Advanced"</span> profile in the web-based editor. Please
- upgrade.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="VALID">4.26. Does Privoxy produce <span class=
- "QUOTE">"valid"</span> HTML (or XHTML)?</a>
- </h3>
- <p>
- Privoxy generates HTML in both its own <span class=
- "QUOTE">"templates"</span>, and possibly whenever there are text
- substitutions via a <span class="APPLICATION">Privoxy</span>
- filter. While this should always conform to the HTML 4.01
- specifications, it has not been validated against this or any other
- standard.
- </p>
- </div>
- <div class="SECT2">
- <h3 class="SECT2">
- <a name="SURPRISE-PRIVOXY">4.27. How did you manage to get Privoxy
- on my computer without my consent?</a>
- </h3>
- <p>
- We didn't. We make Privoxy available for download, but we don't go
- around installing it on other people's systems behind their back.
- If you discover Privoxy running on your system and are sure you
- didn't install it yourself, somebody else did. You may not even be
- running the real Privoxy, but maybe something else that only
- pretends to be Privoxy, or maybe something that is based on the
- real Privoxy, but has been modified.
- </p>
- <p>
- Lately there have been reports of problems with some kind of
- "parental control" software based on Privoxy that came preinstalled
- on certain <a href="https://sourceforge.net/p/ijbswa/bugs/813/"
- target="_top">ASUS Netbooks</a>. The problems described are
- inconsistent with the behaviour of official Privoxy versions, which
- suggests that the preinstalled software may contain vendor
- modifications that we don't know about and thus can't debug.
- </p>
- <p>
- Privoxy's <a href="copyright.html">license</a> allows vendor
- modifications, but the vendor has to comply with the license, which
- involves informing the user about the changes and to make the
- changes available under the same license as Privoxy itself.
- </p>
- <p>
- If you are having trouble with a modified Privoxy version, please
- try to talk to whoever made the modifications before reporting the
- problem to us. Please also try to convince whoever made the
- modifications to talk to us. If you think somebody gave you a
- modified Privoxy version without complying to the license, please
- let us know.
- </p>
- </div>
- </div>
- <div class="NAVFOOTER">
- <hr align="LEFT" width="100%">
- <table summary="Footer navigation table" width="100%" border="0"
- cellpadding="0" cellspacing="0">
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- Configuration
- </td>
- <td width="34%" align="center" valign="top">
-
- </td>
- <td width="33%" align="right" valign="top">
- Troubleshooting
- </td>
- </tr>
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><a href="http://config.privoxy.org/" target="_top">http://config.privoxy.org/</a>, the web-based user
+ interface. <span class="APPLICATION">Privoxy</span> must be running for this to work. Shortcut: <a href=
+ "http://p.p/" target="_top">http://p.p/</a></td>
+ </tr>
+ </tbody>
</table>
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><a href="https://sourceforge.net/p/ijbswa/actionsfile-feedback/" target=
+ "_top">https://sourceforge.net/p/ijbswa/actionsfile-feedback/</a>, to submit <span class=
+ "QUOTE">"misses"</span> and other configuration related suggestions to the developers.</td>
+ </tr>
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><a href="http://www.squid-cache.org/" target="_top">http://www.squid-cache.org/</a>, a popular caching
+ proxy, which is often used together with <span class="APPLICATION">Privoxy</span>.</td>
+ </tr>
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><a href="https://www.irif.fr/~jch/software/polipo/" target=
+ "_top">https://www.irif.fr/~jch/software/polipo/</a>, <span class="APPLICATION">Polipo</span> is a caching
+ proxy with advanced features like pipelining, multiplexing and caching of partial instances. In many setups
+ it can be used as <span class="APPLICATION">Squid</span> replacement.</td>
+ </tr>
+ </tbody>
+ </table>
+ <table border="0">
+ <tbody>
+ <tr>
+ <td><a href="https://www.torproject.org/" target="_top">https://www.torproject.org/</a>, <span class=
+ "APPLICATION">Tor</span> can help anonymize web browsing, web publishing, instant messaging, IRC, SSH, and
+ other applications.</td>
+ </tr>
+ </tbody>
+ </table>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="MICROSUCK" id="MICROSUCK">4.26. I've noticed that Privoxy changes <span class=
+ "QUOTE">"Microsoft"</span> to <span class="QUOTE">"MicroSuck"</span>! Why are you manipulating my
+ browsing?</a></h3>
+ <p>We're not. The text substitutions that you are seeing are disabled in the default configuration as shipped.
+ You have either manually activated the <span class="QUOTE">"<tt class="LITERAL">fun</tt>"</span> filter which is
+ clearly labeled <span class="QUOTE">"Text replacements for subversive browsing fun!"</span> or you are using an
+ older Privoxy version and have implicitly activated it by choosing the <span class="QUOTE">"Advanced"</span>
+ profile in the web-based editor. Please upgrade.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="VALID" id="VALID">4.27. Does Privoxy produce <span class="QUOTE">"valid"</span> HTML
+ (or XHTML)?</a></h3>
+ <p>Privoxy generates HTML in both its own <span class="QUOTE">"templates"</span>, and possibly whenever there are
+ text substitutions via a <span class="APPLICATION">Privoxy</span> filter. While this should always conform to the
+ HTML 4.01 specifications, it has not been validated against this or any other standard.</p>
+ </div>
+ <div class="SECT2">
+ <h3 class="SECT2"><a name="SURPRISE-PRIVOXY" id="SURPRISE-PRIVOXY">4.28. How did you manage to get Privoxy on my
+ computer without my consent?</a></h3>
+ <p>We didn't. We make Privoxy available for download, but we don't go around installing it on other people's
+ systems behind their back. If you discover Privoxy running on your system and are sure you didn't install it
+ yourself, somebody else did. You may not even be running the real Privoxy, but maybe something else that only
+ pretends to be Privoxy, or maybe something that is based on the real Privoxy, but has been modified.</p>
+ <p>Lately there have been reports of problems with some kind of "parental control" software based on Privoxy that
+ came preinstalled on certain <a href="https://sourceforge.net/p/ijbswa/bugs/813/" target="_top">ASUS
+ Netbooks</a>. The problems described are inconsistent with the behaviour of official Privoxy versions, which
+ suggests that the preinstalled software may contain vendor modifications that we don't know about and thus can't
+ debug.</p>
+ <p>Privoxy's <a href="copyright.html">license</a> allows vendor modifications, but the vendor has to comply with
+ the license, which involves informing the user about the changes and to make the changes available under the same
+ license as Privoxy itself.</p>
+ <p>If you are having trouble with a modified Privoxy version, please try to talk to whoever made the
+ modifications before reporting the problem to us. Please also try to convince whoever made the modifications to
+ talk to us. If you think somebody gave you a modified Privoxy version without complying to the license, please
+ let us know.</p>
</div>
- </body>
+ </div>
+ <div class="NAVFOOTER">
+ <hr align="left" width="100%">
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