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39 >Privoxy Frequently Asked Questions</TH
47 HREF="configuration.html"
82 >4.1. How much does <SPAN
85 > slow my browsing down? This
86 has to add extra time to browsing.</A
89 > It should not slow you down any in real terms, and may actually help
90 speed things up since ads, banners and other junk are not being displayed.
91 The actual processing time required by <SPAN
95 itself for each page, is relatively small in the overall scheme of things,
96 and happens very quickly. This is typically more than offset by time saved
97 not downloading and rendering ad images.</P
106 mechanism may cause a perceived slowdown, since the entire page is buffered
107 before displaying. See below.</P
115 >4.2. I noticed considerable
116 delays in page requests compared to the old Junkbuster. What's wrong?</A
119 >The entire page content must be loaded into memory in order for the filtering
120 mechanism to work, and nothing is sent to the browser during this time. The
121 loading time does not really change in real numbers, but the feeling is
122 different, because most browsers are able to start rendering incomplete
123 content, giving the user a feeling of "it works".
126 > To modify the content of a page (i.e. make frames resizeable again, etc.) and
127 not just replace ads, <SPAN
131 the entire page first, do its content magic and then send the page to the
140 >4.3. What is the "http://p.p/"?</A
146 > sits between your web browser and the Internet, it can be
147 programmed to handle certain pages specially.</P
149 > With recent versions of <SPAN
153 greater), you can get some information about
157 > and change some settings by going to
162 > or, equivalently, <A
163 HREF="http://config.privoxy.org/"
165 >http://config.privoxy.org/</A
167 that p.p is far easier to type but may not work in some configurations. With
168 the name change to <SPAN
171 >, this is changed from
172 the previous http://i.j.b/ and earlier 2.9.x versions).</P
177 > forwarded to a server on the
178 Internet - instead they are handled by a special web server which is built in to
184 > If you are not running <SPAN
192 HREF="http://config.privoxy.org/"
194 >http://config.privoxy.org/</A
196 return a web page telling you you're not running
202 > If you have version 2.0.2, then the equivalent is
203 http://example.com/show-proxy-args (but you get far less information, and
204 you should really consider upgrading to 2.9.15).</P
212 >4.4. Do you still maintain the blocklists?</A
215 > No, not by this name. The format of the blocklists has changed
216 significantly in versions 2.9.x and later. This functionality
220 > file now. See next question ...</P
228 >4.5. How can I submit new ads?</A
236 > This process does not work with earlier versions of <SPAN
251 >4.6. How can I hide my IP address?</A
254 > You cannot hide your IP address with <SPAN
257 > or any other software, since
258 the server needs to know your IP address to send the answers back to you.</P
260 >Fortunately there are many publicly usable anonymous proxies out there, which
261 solve the problem by providing a further level of indirection between you and
262 the web server, shared by many people and thus letting your requests "drown"
263 in white noise of unrelated requests as far as user tracking is concerned.</P
265 >Most of them will, however, log your IP address and make it available to the
266 authorities in case you abuse that anonymity for criminal purposes. In fact
267 you can't even rule out that some of them only exist to *collect* information
268 on (those suspicious) people with a more than average preference for privacy.</P
270 >You can find a list of anonymous public proxies at <A
271 HREF="http://www.multiproxy.org/anon_list.htm"
275 more through Google.</P
286 > guarantee I am anonymous?</A
289 > No. Your chances of remaining anonymous are greatly improved, but unless you
290 are an expert on Internet security it would be safest to assume that
291 everything you do on the Web can be traced back to you.</P
296 > can remove various information about you,
300 > more freedom to decide which sites
301 you can trust, and what details you want to reveal. But it's still possible
302 that web sites can find out who you are. Here's one way this can happen.</P
304 > A few browsers disclose the user's email address in certain situations, such
305 as when transferring a file by FTP. <SPAN
309 does not filter FTP. If you need this feature, or are concerned about the
310 mail handler of your browser disclosing your email address, you might
311 consider products such as <SPAN
316 > Browsers available only as binaries could use non-standard headers to give
317 out any information they can have access to: see the manufacturer's license
318 agreement. It's impossible to anticipate and prevent every breach of privacy
319 that might occur. The professionally paranoid prefer browsers available as
320 source code, because anticipating their behavior is easier. Trust the source,
329 >4.8. Might some things break because header information is
333 > Definitely. More and more sites use HTTP header content to decide what to
334 display and how to display it. There is many ways that this can be handled,
335 so having hard and fast rules, is tricky.</P
340 > in particular is often used in this way to identify
341 the browser, and adjust content accordingly. Changing this now is not
342 recommended, since so many sites do look for this. You may get undesirable
343 results by changing this.</P
345 > For instance, different browsers use different encodings of Russian and Czech
346 characters, certain web servers convert pages on-the-fly according to the
347 User Agent header. Giving a <SPAN
351 operating system or browser manufacturer causes some sites in these languages
352 to be garbled; Surfers to Eastern European sites should change it to
353 something closer. And then some page access counters work by looking at the
357 > header; they may fail or break if unavailable. The
358 weather maps of Intellicast have been blocked by their server when no
362 > or cookie is provided, is another example. There are
363 many, many other ways things can go wrong when trying to fool a web server.</P
365 > If you have problems with a site, you will have to adjust your configuration
366 accordingly. Cookies are probably the most likely adjustment that may
367 be required, but by no means the only one.</P
382 speed up web browsing?</A
385 > No, it does not have this ability at all. You want something like
387 HREF="http://www.squid-cache.org/"
390 > for this. And, yes,
391 before you ask, <SPAN
395 with other kinds of proxies like <SPAN
406 >4.10. What about as a firewall? Can <SPAN
412 > Not in the way you mean, or in the way a true firewall can, or a proxy that
413 has this specific capability. <SPAN
417 protect your privacy, but not really protect you from intrusion attempts.</P
428 > logo that replaces ads is very blocky
429 and ugly looking. Can't a better font be used?</A
432 > This is not a font problem. The logo is an image that is created by
436 > on the fly. So as to not waste
437 memory, the image is rather small. The blockiness comes when the
438 image is scaled to fill a largish area. There is not much to be done
439 about this, other than to use one of the other
450 >, or a URL of your choosing.</P
452 >Given the above problem, we have decided to remove the logo option entirely
461 >4.12. I have large empty spaces now where ads used to be.
465 > It would be easy enough to just eliminate this space altogether, rather than
466 fill it with blank space. But, this would create problems with many pages
467 that use the overall size of the ad to help organize the page layout and
468 position the various components of the page where they were intended to be.
469 It is best left this way.</P
480 > filter Secure (HTTPS) URLs?</A
483 > This is a limitation since HTTPS transactions are encrypted SSL sessions
484 between your browser and the secure site, and are meant to be reliably
488 > and private. This means that all cookies and HTTP
489 header information are also encrypted from the time they leave your browser,
490 to the site, and vice versa. <SPAN
494 try to unencrypt this information, so it just passes through as is.
498 > can still catch images and ads that
499 are embedded in the SSL stream though.</P
514 secure is it? Do I need to take any special precautions?</A
517 > There are no known exploits that might effect
521 >. On Unix-like systems,
525 > can run as a non-privileged
526 user, which is how we recommend it be run. Also, by default
530 > only listens to requests
534 >. The server aspect of
538 > is not itself directly exposed to the
539 Internet in this configuration. If you want to have
543 > serve as a LAN proxy, this will have to
544 be opened up to allow for LAN requests. In this case, we'd recommend
545 you specify only the LAN gateway address, e.g. 192.168.1.1, in the main
549 > config file. All LAN hosts can then use
550 this as their proxy address in the browser proxy configuration. In this way,
554 > will not listen on any external ports.
555 Of course, a firewall is always good too. Better safe than sorry.</P
563 >4.15. How can I temporarily disable <SPAN
569 > The easiest way is to access <SPAN
573 browser by using the special URL: <A
578 and select "Toggle Privoxy on or off" from that page. </P
586 >4.16. Where can I find more information about <SPAN
590 and related issues?</A
593 > Other references and sites of interest to <SPAN
607 HREF="http://www.privoxy.org/"
609 >http://www.privoxy.org/</A
630 HREF="http://www.privoxy.org/faq/"
632 >http://www.privoxy.org/faq/</A
653 HREF="http://sourceforge.net/projects/ijbswa/"
655 >http://sourceforge.net/projects/ijbswa/</A
657 the Project Page for <SPAN
662 HREF="http://sourceforge.net"
681 HREF="http://config.privoxy.org/"
683 >http://config.privoxy.org/</A
685 the web-based user interface. <SPAN
689 running for this to work. Shortcut: <A
709 HREF="javascript:w=Math.floor(screen.width/2);h=Math.floor(screen.height*0.9);void(window.open('http://www.privoxy.org/actions','Feedback','screenx='+w+',width='+w+',height='+h+',scrollbars=yes,toolbar=no,location=no,directories=no,status=no,menubar=no,copyhistory=no').focus());"
711 >http://www.privoxy.org/actions/</A
731 HREF="http://www.junkbusters.com/ht/en/cookies.html"
733 >http://www.junkbusters.com/ht/en/cookies.html</A
735 an explanation how cookies are used to track web users.
751 HREF="http://www.junkbusters.com/ijb.html"
753 >http://www.junkbusters.com/ijb.html</A
755 the original Internet Junkbuster.
771 HREF="http://www.waldherr.org/junkbuster/"
773 >http://www.waldherr.org/junkbuster/</A
775 Stefan Waldherr's version of Junkbuster, from which <SPAN
795 HREF="http://privacy.net/analyze/"
797 >http://privacy.net/analyze/</A
799 to check what information about you is leaked while you browse the web.
815 HREF="http://www.squid-cache.org/"
817 >http://www.squid-cache.org/</A
819 caching proxy, which is often used together with <SPAN
838 HREF="http://www.privoxy.org/developer-manual/"
840 >http://www.privoxy.org/developer-manual/</A
870 HREF="configuration.html"