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Synetech
Asked: 2009-07-31 07:55:23 +0800 CST

Apache Rewrite Based on Mime Type

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I’ve got a virtual host in my Apache config to deal with ads, spam, and malware sites. It works by having bad servers redirect to a specific loopback address that is mapped to the virtual host via the HOSTS file.

Using the following directives, I have been able to replace any pages from bad servers with something like [ad] and any graphics from bad servers with a local 1x1, transparent PNG file.

RewriteRule \.(gif|jpg|png|jpeg)$ /1x1-trans.png
ErrorDocument 404 "<p>[ad]</p>"

However recently, I have seen pages with broken IMG tags because they use a SRC without a file extension.

<img src="http://badserver.com/adsandjunk/foobar;tile=4;sz=575x90;othervariables=stuff?">

I tried using

RewriteRule ^.*$ "<p>ad</p>" [L]

But that gives the broken image placeholders again. Using this

RewriteRule ^.*$ /1x1-trans.png [L]

Fixes the images, but then any non-images (like pages, frames, etc.) pop up a Save As dialog for the PNG.

How can I get Apache to replace graphics (ie any IMG tag) with a graphic and everything else with a bit of HTML?

Thanks a lot.

apache-2.2 spam rewrite mime

2 Answers

  1. Just out of curiosity, are you using Apache as a reverse proxy here? That's the only context I can understand you having a virtual host to "deal with ads, spam, and malware sites."

    I'm not sure this is a mod_rewrite issue. You may be better off using filtering:

    http://httpd.apache.org/docs/2.0/mod/mod_ext_filter.html

    Particularly the section where they use sed to replace text. You can use just about anything really, perl, etc.

    I have not done this myself, but the sed route looks promising if you can cobble together the specific search and replace criteria.

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  2. You're doing this the hard way. Just use Privoxy.

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