Proxomitron's filtering limitations
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The Proxomitron can filter most web pages. However, there are a few types of pages and data it won't filter. These include...

Pages that use your browser's security layer (SSL) - These pages usually begin with https:// and are encrypted. They use a different protocol from normal web pages and normally will not be filtered. Since these are most often used for sensitive transactions like on-line purchases or banking this may be for the best. However with Proxomitron Naoko-4 it is possible at least to filter them (although not necessarily trivial or recommended). See the ReadMe.txt file for all the ugly details. In any case use extreme caution before deciding to filter SSL pages. As SSL/TLS has become nearly mandatory and ubiquitous, with Proxomitron Reborn it is highly recommended to configure and turn on HTTPS filtering for best results.

Protocols other than HTTP: The Proxomitron does not filter FTP, gopher, or any other Internet protocol besides HTTP. These protocols are rarely used to display web pages. Don't set your browser's proxy options for other protocols to use the Proxomitron - they won't work (normally ;-).

An important exception: As it turns out, much to my own surprise - if you're using an external proxy server that supports it, you can, in fact, set at least the FTP and Gopher options in your browser to pass through the Proxomitron. This is because the remote proxy server handles all the ugly details involved with each particular protocol - useful for those who make use of the proxy switching feature.

'Websocket' connections - This is a "sneaky" way of tunneling another protocol inside HTTP, and some sites (e.g. those with realtime data updates) may depend on websockets to function. Proxomitron knows nothing about websockets, so when it's filtering, attempts at websocket communication will fail. You can bypass if you trust the site and it can't work without websockets, but Proxomitron currently won't be able to tell you what's flowing through a websocket connection nor do any filtering.

Content types other than html, javascript, and gif images - The Proxomitron will send any other type of data unchanged. This ensures zip files and other binary data are never corrupted. Note that the HTTP headers for other data types can be affected - so be careful here. Also, you can manually override this by using the $FILTER(True) matching command in a header filter, but if you do, be careful. At the very least, make sure what you're filtering is text-based.


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