The Proxomitron

The Proxomitron is a very powerful local proxy which is useful for removing adverts / popups / rewriting cookies / etc. It rewrites any web page using a very powerful filtering mechanism that enables it to do almost anything. It uses far less processor resource than many other types of ad-removing proxies, and is free to use. It is somewhat intimidating for novice users, but is worth taking the time to learn to use. Filters are based on customised RegExp's.

The original author is deceased, however most of the power of The Proxomitron comes from the filters used, and these are still being developed actively. That means that The Proxomitron can still keep adapting and changing for a good while yet with its power little diminished.

How to Use the Proxomitron to Understand Browsing Problems

One brilliant feature of the Proxomitron (even compared to several packet sniffers that make it harder to get this info in real time, and certainly can't modify requests dynamically) is the "log connections" feature which details the HTTP headers (the hidden conversation between browser and remote server, including POSTed data). This allows one to understand what is happening between the browser and remote server, and analyse whether a problem with a web page is actually a problem from a misconfigured server. By rewriting the HTTP headers sent or recieved in real time, it also becomes much easier to determine what exactly is the problem by testing various hypothesese through header manipulation.

Below are a few filters that help in various ways. To install them select the text in the code box, then copy to clipboard. Go to Proxomitron, open up the filter window, then right-click and 'Import filters from clipboard' to add them to your existing filters.

Fully Cloaking Opera's Identity

Opera allows the User Agent to be changed easily through Quick Prefs (F12) - but this still leaves the word 'Opera' in the identity line, and also sites that check using javascript bypass the identity line altogether. The Proxomitron comes with Header filters to fully change user identity by default, but cannot cloak the javascript mechanism. Andrew Gregory has greatly extended some filters developed by HallVord, now fooling most browser sniffers of the major tell-tale signs of Opera. Used along with the User-Agent Header filters, this will provide almost total cloaking of Opera from browser detection (check here):

Cloaking Opera

Cross-Browser Page Load Timer

The Proxomitron can act as a cross-browser way to measure page-load times! Use these filters:

(add to Web Page Filters)

[[Patterns]
Name = "Page Load Timer I"
Active = TRUE
URL = "$TYPE(htm)"
Limit = 50
Match = "(^(^<head>))"
Replace = "<script type="text/javascript">\n"
		  "<!--\n"
		  "var startDate=new Date();\n"
		  "function endT() {\n"
		  "var endDate=new Date();\n"
		  "loadT=('Load Time: '+(endDate.getTime()-startDate.getTime())/1000+' second(s)');\n"
		  "document.title=document.title.substr(0, 80)+'... '+loadT;\n"
		  "window.defaultStatus=loadT;\n"
		  "}//-->\n"
		  "</script>$STOP()"

Name = "Page Load Timer II"
Active = TRUE
Multi = TRUE
URL = "$TYPE(htm)"
Limit = 4096
Match = "<end>"
Replace = "<script type="text/javascript">window.onload=endT();</script>$STOP()"

Note that Mozilla FireFox has a bug whereby it claims it has loaded a page when it is still loading images or other inline content embedded in a CSS file. For these types of pages, this script will return faster load times for FireFox compared to Opera / IE.

Links:

Proxomitron Home Page
Main Mailing List
Computer Cops Proxomitron Forum
Sidki's Filter set
JD5000's Filter set

Categories

CategoryTechnical CategoryTutorial

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