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Surfing with the Proxomitron

A Series of Explorations

by AnonyMouse

This is an essay/tutorial to introduce new users to some of the functions of the Proxomitron Universal Web Filter, an essentially freeware creation by Scott R. Lemmon. It is available for download at http://members.tripod.com/Proxomitron/ The Proxomitron runs under any 32 bit version of Windows. The default set of filters easily runs on a 120 MHZ Pentium; adding more filters requires more power, while a less powerful machine will probably require disabling some of the default filters for best performance.

The power of the Proxomitron lies in its ability to rewrite webpages on the fly, filter communications between your computer and the web servers of the sites you visit, and to allow easy management of external proxy use. Among the people with whom I've corresponded who use it, it's primarily valued for its ad filtering and privacy enhancing potential, although a multitude of other uses are examined on the Proxomitron website.

This essay will consist of a series of hands‑on explorations and exercises specifically designed to allow intelligent but possibly inexperienced Net surfers to use and customize the Proxomitron in ways to enhance their privacy while surfing the Web. All references to the Proxomitron in this essay refer to version 3b and the default.cfg filter file. Other versions and .cfg files will differ in some details. Users concerned with issues other than privacy will find the general descriptions applicable to customizing the Proxomitron for other purposes as well. Descriptions in this essay rely heavily on mouse clicking, but keyboard shortcuts are usually specified on the Proxomitron's windows and dropdown lists for those who prefer using their keyboards.

Getting Started.

Begin by surfing to http://members.tripod.com/Proxomitron/download.html and downloading the Proxomitron version with full installation (ProxN3i.zip, not ProxN3.zip). Unzip it, double click the setup.exe file, and click a few buttons on pop‑up screens to allow the default installer to do its thing: Yes, Next, Next, Next, Next, Install, Finish. A "Read Me" file will then pop‑up and give you a brief overview of the history of the program. Click out of it when you've satisfied your historian's instincts and we'll get down to configuring your browser to use your new tool. This differs slightly from browser to browser. Begin by launching you browser of choice.

* If you use Netscape, click on "Edit". Select "Preferences", click on the + sign next to "advanced", then click on "proxies". Click on "Manual proxy configuration", then "View". Next to "HTTP:" type "localhost" (without the quotes) and for the port type "8080" (without the quotes). The Proxomitron only supports the HTTP protocol (the ones used by webpages that have a URL beginning with "http://"), so don't try to use it for the other settings. Click OK to save your new settings.

* If you use Internet Explorer 3 or 4, click on "View", then "Internet options...", then the "Connections" tab. Click on "Use proxy server", then "settings" or "advanced" (different versions use different words here). Next to "HTTP:" type "localhost" (without the quotes) and for the port type "8080" (without the quotes). The Proxomitron only supports the HTTP protocol

(the ones used by webpages that have a URL beginning with "http://"), so don't try to use it for the other settings. Click OK to save your new settings.

* If you use Internet Explorer 5, click on "Tools", then "Internet Options...", then the "Connections" tab. Important: Do not click on "LAN Settings" unless you are actually on a LAN. Everyone else should click on "Settings..." and place a check mark in the box next to "Use a proxy server" by clicking on the box until a check mark appears there. Make sure that you do not have "Use automatic configuration script" checked just above there. Now click on "Advanced..." and next to "HTTP:" type "localhost" (without the quotes) for the "Proxy address to use" and "8080" (without the quotes) for the port. The Proxomitron only supports the HTTP protocol (the ones used by webpages that have a URL beginning with "http://"), so don't try to use it for the

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other settings. Click OK to save your new settings.

* If you use Opera, click on "Preferences", select "Proxy Servers", then next to "HTTP:" type "localhost" (without the quotes) and "8080" (without the quotes) for the port. The Proxomitron only supports the HTTP protocol (the ones used by webpages that have a URL beginning with "http://"), so don't try to use it for the other settings. Click OK to save your new settings.

Whatever browser you use, in general, just launch your browser and open up your browser's proxy configuration window. Next to "HTTP:" enter the proxy name as "localhost" (without the quotes) and the port number as "8080" (again, without the quotes). Click OK to save your new settings.

Now click on the green triangular Proxomitron icon that is on your desktop. This launches the Proxomitron and places a small green triangular icon on the toolbar next to your clock.

That's it. Yes, really, that's all there is to it! From now on, every HTTP webpage you visit will be filtered through the Proxomitron before it reaches your browser. Just remember to launch the Proxomitron by clicking on its desktop icon every time you want to surf. If you've configured you browser this way, if you forget to launch the Proxomitron, you won't be able to access any webpages.

The "default.cfg" file of filters works fine for most people, and you can probably skip this paragraph, but if you use Opera, IE3, or if you have problems with low bandwidth ("slow modem") connections, special filter files are provided. To use one of these, right click on the Proxomitron triangular icon next to your clock and select "Load Config File". This opens a window which lists several config files you may choose from. If you use Opera, IE3, or have "Low Bandwidth", click on the file most appropriate for you, then click on "Open" to load it for you to use by default. The other files listed here mostly change the appearance of the Proxomitron, but explore loading them if you wish. Now that you know how easy it is to select another filter file, you can easily change back to the one most appropriate for you any time you wish. Each time the Proxomitron is launched, the filter that is automatically loaded is the one named "default.cfg". If you want to use one of the other filters all the time, you might change the name of the original "default.cfg" to something else like "original.cfg" and rename the .cfg file you want to use as "default.cfg" to avoid having to change to it manually every time. Advanced users may later want to have several different .cfg files which they switch between depending on what kinds of sites they're surfing to: one for business, one for checking online email accounts, one for "underground" sites, etc. to easily fine tune the filters they're using.

Exploring.

For those satisfied with Scott Lemmon's excellent default filters, you can stop reading this and start surfing. For those who want to explore the Proxomitron's capabilities and enhance the default settings to better meet their specific needs, read on...

(Please note that this essay will _not_ be exploring _every‑ option the Proxomitron offers, only the most basic ones. Feel free to consult the Proxomitron's Help file at any time for further information about the options we look at and, more importantly, the ones we leave out. After you have chosen the .cfg file which is most appropriate for you, I would suggest that you leave all the filters that are turned on by default turned on. As we examine them, I'll also be suggesting that you might want to activate some of the filters that are left turned off by default.)

Ready? First right click on the Proxomitron icon next to the clock and choose "Open Proxomitron" and let's start exploring. (We'll examine the other options on the right click dropdown menu at the end of this essay.)

The Main Window.

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The Proxomitron's main window that opens has a toolbar at the top that contains the words "File" and "Help" and three icons: a floppy disk with an arrow pointing left, a floppy disk with an arrow pointing right, and an up arrow. Clicking on "File" brings up a menu which allows you to manage the "config files" that make the Proxomitron perform its various tasks. Clicking on "Help" opens the Help file which will provide much more in depth information about how to use the Proxomitron than this little essay can attempt to do. Clicking the floppy disk with an arrow pointing left saves any changes you make to your config file, so that the changes will now be in effect. Clicking the floppy disk with an arrow pointing right reloads your config file in case you ‑don'twant to save any changes you've made, much like a Reset or Undo button, reloading the config file you had the last time you saved it. Clicking the up arrow launches any program or URL you specify, such as your browser or your homepage. (We'll see how to make that specification in a moment.)

In the middle of the Proxomitron's main window are two boxes. The box on the left is "Active Filters". The check mark next to a filter name means that set of filters is active, that it is in effect or "on". No check mark means you're not using that specific set of filters. Clicking check marks on or off here is an easy way to enable or disable groups of filters. The box on the right is "Edit Filters".Clicking on any of these buttons opens up a window listing the filters in that group. (We'll look at these in some detail in a moment.)

At the bottom of the Proxomitron's main window are three buttons. Clicking on "Bypass" means that you're not using any of the Proxomitron's filters, that you're seeing the webpages just as you saw them before you ever installed the Proxomitron. (If you are using an external proxy, however, you will still be surfing through that proxy even if you click on "Bypass".) Clicking on "Abort" closes any currently loading webpage, acting as a fallback in case your browser's "Stop" button doesn't work. Clicking on "Log Window" opens an "HTTP Message Log" window that shows you the information passed back and forth between the Proxomitron and the sites you surf to, the Proxomitron filters that are operating on the page you're at, and information useful for debugging filters. (Advanced users report that they routinely open this Log window to monitor their Net surfing activities, but even novices often find it interesting to watch and learn what's going on "behind the scenes" in the flow of information between their browser, the Proxomitron, and the web servers for the sites they surf to.) Below these three buttons is a status window that lists the current number of active connections your browser is filtering through the Proxomitron; it also lists various messages about what the Proxomitron is doing.

For all those things I promised to explore with you later, well, it's "later"...

Edit Filters.

The "Edit Filters" box on middle right box on the main screen contains four buttons. Clicking on any of them opens up a window that lists all the filters in that group. Let's briefly examine each one.

Web page.

Click on "Web page" and you'll open a window which lists all the preconfigured HTML Web Page Filters. Each one that is turned "on" in this group has a check mark next to it and its title is written in bold print. A filter without a check mark next to it is turned "off". You can easily change the filters you want to use in a group by adding or deleting a check mark next to it.

(Remember, though, that for the checked members‑ of a group to really be in effect, that group‑ must be checked on the main window!) To the right of this list of filters are several "Options" buttons that allow you customize specific filters to meet your individual needs. These are the controls that let you write and test your own filters and to add other filters to the ones that come with the Proxomitron. More advanced users will spend a lot of time doing just that, but for now we'll pretty much stick to using or not using the filters that are already provided, slightly modifying a few of them.

The default settings are excellent choices for most surfers, but I've been asked

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to make suggestions about how to enhance the defaults to promote privacy when surfing, so that's what we'll do in some examples to demonstrate the basics of some of these filters.

First, you should have already have clicked on "Web page" on the main window and you should be seeing a window with "HTML Web Page Filters" written at the top. many of these that are checked already provide a measure of privacy enhancements, but several of the ones which are unchecked by default could be checked to enhance surfing privacy, too.

For those concerned about JavaScript, the Proxomitron offers a flexibility your web browser lacks. You can disable all JavaScripts or pick and choose to disable only the ones that you find irritating. To kill all JavaScript, scroll down the list and check the filter called "Disable JavaScript". To selectively disable some JavaScripts while allowing others to run, consider leaving that one unchecked and check one or more of the following: "Kill Nosey JavaScripts" (this one kills all JavaScripts that record your browser's referer, cookies, plugins, color depth, pixel depth, and history), "Disable JavaScript cookies" (one type of cookie; note that blocking JavaScript cookies does not block cookies passed via HTTP Headers and blocking cookies passed via HTTP Headers does not block JavaScript cookies, so if cookies concern you, be sure to block both kinds), "Hide Browser's Version from JS", and "Hide Browser's Identity from JS" (what browser you're using). If you check any of these, though, be aware that some sites will appear very differently or block you from accessing them at all. On the other hand, some sites will now allow you in that may have blocked you before, since now you have the "correct" browser or you didn't click on the link from a "bad" site to get to their's. For those who "want to selectively kill only some of the "nosey" JavaScripts without using the "Kill Nosey JavaScripts" filter, BrasldaS has developed a series of filters for doing that and has made them available for download at http://home.cyberarmy.com/brasidas/proxomitron.html . He has added HTTP Header filters and JavaScript filters to kill other privacy intruder JavaScripts as well. Download his Privacy Packl.zip now and I'll show you how to install his filters later in this essay.

Before you check "Hide Browser's Version from JS" and "Hide Browser's Identity from JS", though, we need to edit them to be less conspicuous than the default settings of "2.1" and the mythical "ShonenScape" respectively. To edit a filter, click on the filter's name to highlight it, then click on the "Edit" button. First, click on "Hide Browser's Version from JS" and click on "Edit" to bring up a filter editing window. At the bottom, just replace '2.1' with 'S.0' and click OK. Click on "Apply" to save the change (and put a check mark next to "Hide Browser's Version from JS" by clicking on the empty box if you really want to use this filter). That's it! Now click on "Hide Browser's Identity from JS" and click on "Edit" to bring up a filter editing window. At the bottom replace 'ShonenScape' with 'Internet Explorer' and click OK. Click on "Apply" to save the change (and put a check mark next to "Hide Browser's Identity from JS" by clicking on the empty box if you really want to use this filter). From now on, regardless of what browser you really use, sites that use JavaScript to detect your browser will believe that you're using Internet Explorer 5.0, a browser common enough to allow you toblend into the crowd of ordinary web surfers without attracting attention to yourself! (Obviously you can change this to whatever browser you like.)

Once you've finished selecting all the filters you want to use in this section, click on OK to return to the main window. Now click on "Headers" and we'll examine using those filters to enhance privacy.

Headers.

HTTP Headers are the messages you browser passes back and forth with webpage servers that allow you to connect to them to see a webpage. Next to each of the filter names is an "In" box and an "Out" box, reflecting that some headers are sent into_ your browser from the web server and others are sent ‑out_ of your browser to the web server. Again, you should be aware that using any of these filters may prevent you from accessing some sites or seeing some pages. If your main concern is privacy, it's the ones going out that are of major interest.

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If you're concerned about cookies, note that you can either block all cookies coming into your browser via HTTP Headers by checking "Set‑cookie: Never accept cookies (In)", block all HTTP Header cookies from leaving your browser by checking "Cookie: Kill a cookie (out)", or (for more advanced spoofers) you can write your own cookies and send them to sites using "Cookie: Fake a cookie (out)". Again, killing cookies may block you from some sites and learning how to fake cookies requires some additional reading beyond the scope of this essay. Also, remember that blocking cookies passed via HTTP Headers does not block JavaScript cookies and blocking JavaScript cookies does not block cookies passed via HTTP Headers, so if cookies concern you, be sure to block both kinds.

Advanced users might consult: http://info.internet.isi.edu/in‑notes/rfc/files/rfc2lO9.txt http://home.netscape.com/newsref/std/cookie_spec.html http://www.cookiecentral.com/

If you're concerned about the HTTP headers that show up in ENV variables your browser sends out, you can also kill or fake those using additional filters in this section. These are important enough to examine them individually.

"Forwarded:" if checked, fakes the path you use in connecting to a web server. You can edit the default by changing the /h to read whatever you wish. Using this filter makes it hard to tell where you're coming from.

"User‑Agent:" if checked, fakes the browser and Operating System you use. Again, to more easily blend in, we need to edit the default if you want to use this filter. Click on "User‑Agent:" to select it and click on "Edit" to bring up a filter editing window. At the bottom replace the mythical SpaceBison/0.01 [fu] (Win67; X; ShonenKnife) with Mozilla/4.0 [fr] (compatible; MSIE 5.0; Windows 98) and click OK. Click on "Apply" to save the change (and put a check mark next to "User‑Agent:" by clicking on the empty box if you really want to use this filter). Notice that this identifies you as using Internet Explorer 5.0 and Windows 98 with a language preference for French. If you want to use other choices, several can be found in online logfiles; search for the phrase "Web Browser Agent statistics" and scroll down the page to the section called "Detailed:". From now on you can appear to have any browser and Operating System you like, or even be a search engine spider or bot if you want.

"X‑Forwarded‑For:" if checked, fakes where you've been routed from. Again, to more easily look like other surfers, you might change the default to /h so that the site you're on would tell itself that you've been at that very site the whole time and that you've never been anywhere else. Talk about loyalty!

Other ENV variables can be controlled by constructing your own filters. Advanced users might consult: http://www.w3.org/Protocols/HTTP/HTRQ‑Headers.html http://perlfect.com/articles/cgi env.shtml or just examine the variables listed on an ENV test page like the ones at http://www.interlacken.com/tricks/exec/trick02/egyprop.asp http://cgi.tky.3web.ne.jp/‑aniki/cgi‑bin/env.cgi or the sites that BrasldaS and I collected at http://proxys4all.cgi.net/envcheckers.html

Once you've finished selecting all the filters you want to use in this section, click on OK to return to the main window. If you want to use the filters for header information going out of your browser, place a check mark next to "Outgoing Header Filters". If you want to use the filters for header information going into your browser, place a check mark next to "Incoming Header Filters". If you never want to see another animated .gif like those opening and closing mailboxes and spinning skulls, place a check mark next to "Freeze .GIF Animation" and you'll only see their first frame.

Config.

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Now click on "Config". On the left you'll see controls that allow you to change the Proxomitron's appearance. On the right is the "Listener Port", which defaults to 8080. (Now you know why we entered port 8080 into your browser's proxy configuration. If you want to change it to a different port, here's where you can do that, but if you do, be sure to change the port in your browser, too.) There's also a place to enter a program or URL to run. Entering the location of your browser's .exe or your homepage URL here will launch your browser every time you launch the Proxomitron, a handy automation. A check mark next to "Minimize to System Tray" makes the Proxomitron open to an icon next to your clock when you launch it. The defaults here are fine, but play with them if you like. Once you've finished, click on OK to return to the main window.

Proxy.

Click on "Proxy" to open the "External Proxy Selector" window. Click on "Add" and you'll get a window to write in a proxy you'd like to use. These must be written in the form IP:port or hostname:port. If no port is specified, 8080 is assumed. Any of these would be fine: 128.61.15.11:3128 oregano.ulcc.wwwcache.ja.net:8080 owl.tezukayama‑u.ac.jp Once you've typed in a proxy's IP or hostname and port, click on "Test" to see if the proxy is working. If it is, click OK and it's ready to use. If it doesn't work, click "Cancel" and it won't be added to your proxy list. Once you've entered a proxy you'd like to use, be sure to put a check mark next to "Use Remote Proxy" on the main screen so that the Proxomitron knows you actually want to use a proxy.

Some external proxy users have lists of several proxies they like to rotate between as they surf. Here is another of the Proxomitron's strong points. To manage such a list, click on "Proxy" again to open up the "External Proxy Selector" window. Now right click on the bar where your proxy name and port is listed. You'll get a dropdown menu with several choices.

Selecting "Advanced Proxy settings" opens up a window that lets you add a check mark to rotate your proxies to use a new one every 5 connections. (If you check it, you may change the 5 to whatever number you please, allowing you to use a different proxy as often as you like.) Selecting "Remove proxy from list" will delete only the currently displayed proxy, while choosing "Clear proxy list" deletes all the proxies you've entered. "Cut", "Copy", "Paste", "Delete", and "Select All" allow you to edit your lists easily and the "Undo" option restores your old list if you make a mistake. If you right click the window that pops up when you click the "Add" button, you'll also get a dropdown menu for "Undo", "Cut", "Copy", "Paste", "Delete", and "Select All" as another aid in editing.

To add new filters or proxy lists.

Individual new filters or proxies can be entered manually by clicking on the appropriate filter group name, clicking on "New" or "Add", typing in the information in the appropriate spaces, then clicking OK and either "Apply" or OK again to save the new information. For those wanting to add several new filters at once or to add large lists of proxies, there's a shortcut. Go back to the main window and click on "File" and choose "Merge config filters". You'll get the "Config Filter Merge‑O‑Matic" which allows you to locate where your list of new filters is, then select by checking the appropriate box whether this new list contains "Global Settings", "Web Filters", "Header Filters", or an "External Proxy List".

Hopefully by now you've gotten BrasldaS's JavaScript filters. To add these filters to the ones the Proxomitron already has, go to the main screen, click on "File" and select "Merge config filters". Find where you saved BrasldaS's filter .cfg file and click on it to select it so that its name appears in the box called "File Name". This file contains both "Header Filters" and "Web Filters", so make sure that both those boxes have a check mark in them. Now click on "Open" and all of BrasldaS's filters will be added to your list. I'll let you explore them at your leisure and select which ones you want to use. If

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you want to keep them, be sure to click the green floppy disk with an arrow pointing left at the top of the Proxomitron's main window.

You can open BrasldaS's .cfg file in a text editor like Notepad to see how he wrote it if you'd like to write your own filters and distribute them. The Proxomitron's Help file contains detailed instructions about the grammar used in writing new filters. Several other filters are available for downloading at: http://members.tripod.com/Proxomitron/newfilters.html

Adding proxy lists is just as easy, but most people will have to write their own list rather than using one someone else has already prepared. Luckily, this is easy. Open a text editor like Notepad and write [Proxies] one the first line, including the brackets. Leave the next line blank, then list all the proxies you want to use, making sure that you have each one on a separate line. If you want to, you can write comments for any of the proxies by skipping a space after the port number and writing whatever you please. These would be acceptable: oregano.ulcc.wwwcache.ja.net:8080 not anonymous 128.61.15.11:3128 but this would not be, since no space was skipped: 128.61.15.11:3128fast and anonymous When you've entered them all, leave two blank lines at the end of the list and save the list to a file. To add these proxies to your Config file, go to the main screen, click on "File" and select "Merge config filters". Find where you saved your proxy list file and click on it to select it so that its name appears in the box called "File Name". These are all items on your "External Proxy List", so make sure that box has a check mark in it. Now click on "Open" and all of these proxies have been added to Proxomitron's proxy list. If you want to keep them, be sure to click the green floppy disk with an arrow pointing left at the top of the Proxomitron's main window.

Extensive lists of proxies are available at several sites such as these: http://fsu.virtualave.net/cgi‑bin/fp.pl/showlines?lines=2000 http://proxys4all.cgi.net/proxy.html http://www.lightspeed.de/irc4all/eproxy.htm http://www.ijs.co.nz/proxies.htm (and subsequent pages)

Not all of the proxies listed at these sites are anonymous, so if privacy is important to you, you'll need to test each one by following the directions at this page: http://proxys4all.cgi.net/env‑checkers.html In addition to enhancing privacy while surfing, external proxies can be used to perform a wide variety of different tasks as is discussed at: http://proxys4all.cgi.net/files/why_proxy.txt Proxies often become unuseable, so that your list will need to be updated periodically by deleting any dead proxies and adding new ones from the sites listed above.

Troubleshooting and fine tuning using the main right click menu.

Once you've selected which filters you want to use in each group, you've entered your proxy list, you've launched your browser and the Proxomitron, and you're connected to the internet, most users find that the Proxomitron's settings rarely need to be managed. If you encounter some difficulties, such as being blocked from a site because you won't accept cookies or your JavaScript filters prevent you from seeing a page, you can easily change the filters that are in effect by toggling the Proxomitron's groups of filters off and on using a simple dropdown menu.

Right click on the triangular Proxomitron icon next to your clock and you'll see several options. Select "Open Proxomitron" to see the main Proxomitron window. Selecting "Web Page Filters", "Outgoing Header Filters", "Incoming Header Filters", or "Freeze .GIF Animation" to turn each of these groups of filters on or off, activating them or deactivating them. (A check mark in front of its name means a filter group in "on" and no check mark means it's "off".) Selecting "Bypass" means that you're not using the Proxomitron filters any more

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to do anything other than to use a remote proxy if you have entered one to use. Placing a check mark next to "Use Remote Proxy" means that you'll be surfing through the last selected proxy you've added to your proxy list. To easily see which proxy that was, select "Switch Proxy" from the right click dropdown list and the proxy you're using will have a check mark next to it. To manually change the proxy you're using, select "Switch Proxy" and click on a different proxy from your list. Selecting "Open Log window" opens the "HTTP Message Log" window that we've already looked at. Selecting "Load Config File" lets you use a different set of filters than the one you currently have in use. "Exit program" simply shuts the Proxomitron down.

Conclusion.

I hope that going through these exercises has helped you to see some of the ways the Proxomitron can be used when web surfing. Questions, comments, or suggestions you may have concerning this essay may be addressed to AnonyMouseat‑dragoncon.net . If you want to distribute this essay to anyone else in any shape, form, or fashion, please don't do that. If you want to thank me for my work, share a copy of any new filters you run across which are not posted on the official Proxomitron site or which you have created yourself. I want to thank Scott Lemmon, BrasldaS, and Bone Digger for the invaluable work they've done and the suggestions they've made to improve this essay. Any errors or confusions that remain are entirely my own fault.

October 25, 1999

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