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Ionic's ISAPI Rewrite Filter aka IIRF for IIS8+

By Nelson Pires
Updated on

Ionic's ISAPI Rewrite Filter is a very popular and free filter for URL rewriting in IIS. The latest official version does not work in IIS8+. I only recently moved from IIS7 to IIS8 and have been using IIRF- for a long time on IIS7 (my preferred URL rewriting mechanism as its easy and fast), so, to my complete dismay, it would not work on IIS8 and I have quite a few sites that depend on it.

After some digging, I realised only the redirect rules fail while the rewrites are ok, this turned out to be an issue with the code and something other people have fixed but did not make the fix publicly available.

I requested the new fixed DLL from a number of people to which Pavel Surikov responded and gave me his new and improved code revision. Thanks Pavel. He added one extra feature besides fixing the broken redirects for IIS8+; support for IPv6. So IIRF- is the version to have if you run IIS8 and above.

One other way to run IIRF on IIS8+ is to use the old IIRF- version from the official website. But there are a couple of issues with it;

  1. This version is only available in 32bit, so in order for it to run in IIS8+ which is 64bit, one would have to go to advanced settings on the application pool of the site running IIRF and set [Enable 32-Bit Applications = True]
  2. We also lose all the bug fixes and new features added after this version

The official IIRF CodePlex project seems to be stuck in version IIRF- for quite a while which is a shame for such a nice filter.

A lot of people now use the Microsoft URL Rewrite module (including myself), but IIRF still has a place in my armoury for its ease of use.

I'm not sure if the license agreement allows me to redistribute this new code revision but if anyone has an objection, please let me know.



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