In this post I'll show you how to install Helicon Ape in Windows Server IIS and how to use .htaccess files for your website. Yes, expect a lot of .htaccess examples for IIS :) Further this post describes some common uses of .htaccess files by PHP applications like WordPress, Joomla, Drupal, or your own coded CMS. For example how to manage subdomains or HTTPS redirections.

.htaccess files are configuration files for Apache-based webservers. Using a .htaccess file allows you to set up rewrite condition and rules, redirects, cache validation / invalidation or password protecting directories. Did you know you can use .htaccess files in Windows Server IIS? This post provides you with easy and ready to use examples for .htaccess files on IIS web servers. To be able to use .htaccess files on IIS, you need to have Helicon Ape installed.

URL Rewriting in IIS with .htaccess files

Before IIS 7 and the IIS URL Rewrite Module, you had to rely on third party extensions to IIS for URL rewriting with .htaccess files. One example of such an extension is the widely used ISAPI_Rewite 3 by Helicon Tech. Helicon ISAPI_Rewrite is superseded by Helicon Ape nowadays. Helicon Ape provides support for Apache .htaccess and .htpasswd configuration files in Microsoft IIS.

Here is some information for you to use .htaccess in IIS.

Using such an extension made search engine friendly URL's with WordPress Permalinks or Joomla SEF possible, and some other neat stuff like protecting your website from 0-day exploits or to hiding the .php extension with URL Rewrite Module & Helicon Ape. Emulating Apache MultiViews on IIS, both web.config and .htaccess examples in that post! :-)

Since IIS 7 and the IIS URL Rewrite module, you can add rewrite rules to your website's web.config file. You can convert your old Apache .htaccess to web.config manually or automatically. Learn how to translate .htaccess content to IIS web.config.

However you can always install and use Helicon Ape on an IIS web servers to process .htaccess files. This makes your website more cross-platform.

About Helicon Ape

Helicon Ape is an Apache emulator for Microsoft IIS. It literally implements Apache configuration model (like .htaccess and httpd.conf files) and all most demanded Apache modules in a single IIS add-on, not only making IIS compatible with Apache, but also extending it’s functionality by a number of highly essential features. You can check all currently available modules in the compatibility chart (the list is growing with new builds).

Helicon Ape is implemented as managed IIS 7 (7.5) module, but can be installed as .NET module on IIS 6 as well. It works transparently for both server and client and can even be installed on a shared hosting account without administrative access.

Includes following modules: mod_rewrite, mod_proxy, mod_auth, mod_gzip, mod_headers, mod_cache, mod_expires, mod_replace and others.

Helicon Ape overview

About IIS URL Rewrite

IIS URL Rewrite 2.0 enables Web administrators to create powerful rules to implement URLs that are easier for users to remember and easier for search engines to find. By using rule templates, rewrite maps, .NET providers, and other functionality integrated into IIS Manager, Web administrators can easily set up rules to define URL rewriting behavior based on HTTP headers, HTTP response or request headers, IIS server variables, and even complex programmatic rules.

In addition, Web administrators can perform redirects, send custom responses, or stop HTTP requests based on the logic expressed in the rewrite rules.

URL Rewrite - THe Official Microsoft IIS Site

All .htaccess examples are for Helicon Ape. Please note Helicon Ape hasn't been updated in years, it's better to use IIS URL Rewrite Module.

.htaccess examples for IIS

The .htaccess examples I describe are:

WordPress Permalinks .htaccess

Helicon Ape recognizes existing directory and existing file as test strings for %{REQUEST_FILENAME}. By negating we turn this around which makes the rules only processed if a request_filename is not an existing file or directory. All those requests are then rewritten to WordPress' index.php file for internal handling.

# Enable the RewriteEngine.
RewriteEngine On

# When the HTTP request doesn't match and existing file 
# or directory, Rewrite the request and send it to the 
# index.php file
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

And some would still say search engine friendly URL's are not possible on IIS with .htaccess files... sigh

Rewrite linked domains to one master website (how to map multiple domains #1)

Most hosting providers offer the ability to map multiple domains to one master domain and/or webspace.

Let's say you have,, and hosts your website. You'd like to have all requests for,,, to be rewritten to, how would you accomplish that?

Of course you can list all domain names in your .htaccess file, but that doesn't scale easily. Therefore, you can map all incoming HTTP request, except for, to your main website on You can choose to rewrite the requests, but for Google Search Engine Optimization (SEO), and duplicate content, it's better to permanently redirect them with a 301 redirect. And here is how!

Add to your .htaccess:

# Enable the RewriteEngine.
RewriteEngine On

# Rewrite the HTTP request for every mapped domain to the 
# master domain. Replace "" with your master 
# domain name.
RewriteCond %{HTTP:Host} ^(?!www\.example\.com)$ [NC]
RewriteCond %{REQUEST_URI} (.+)
RewriteRule .? http://www\.example\.com%1 [L,R=301]

This one also takes care of the REQUEST_URI, meaning that a request for will be redirected to

Linked domains to a subfolder on the master website (how to map multiple domains #2)

The same as above, we want to map multiple domain names to our master domain. But now map them to a subfolder, for example for different languages:,,,

All requests are automatically mapped to a sub-folder with the same name as the domain name. Be aware of that!

# Enable the RewriteEngine.
RewriteEngine On

# Rewrite a HTTP request for a mapped domain to a subfolder, 
# with the name of that domain.
# Replace with your domain name, on the first 
# and third line
RewriteCond %{HTTP:Host} ^(?:www.)?example\.nl$
RewriteCond %{REQUEST_URI} (.+)
RewriteRule .? example%1 [L]

We can probably make this more robust:

# Enable the RewriteEngine.
RewriteEngine On

# assuming the domain is always example, with several ccTLD's.
# We list all ccTLD's for convenience.
RewriteCond %{HTTP:Host} ^(?:www)?\.example\.(nl|be|de|co\.uk|fr)$
RewriteCond %{REQUEST_URI} (.+)
RewriteRule .? %2%3 [L]

This should map to

Manage and rewrite subdomains on IIS with Helicon Ape

As with the above .htaccess to map a linked domain to a subfolder, we can do the same for subdomains. A subdomain substitutes www in the address bar, for example.

# Enable the RewriteEngine.
RewriteEngine On

# Rewrite any subdomain to a folder with the same name, 
# except for www. Nothing is rewritten if no subdomain 
# is used.
# Subdomains like "" are rewritten to "/foo",
# "" to "/".
RewriteCond %{HTTP:Host} ^((?!www.)(.+)|(?:www.)(.+)).(example\.com)$ [NC]
RewriteCond %{REQUEST_URI} (.+)
RewriteRule .? %2%3%5 [L]

How to rewrite your non-www domain to www (canonical domain names, to

In order to not to display double content - which is bad for your Google SEO - we need to rewrite non-www URL's to www. Assuming we want to have our website available on Again we use a 301 permanent redirect.

Again, REQUEST_URI is included too.

# Enable the RewriteEngine
RewriteEngine On

# Rewrite any HTTP request for a domain name without 
# www to www.domain name.
RewriteCond %{HTTP_HOST} ^(?!www.)(.+)$ [NC]
RewriteCond %{REQUEST_URI} (.+)
RewriteRule .? http://www.%1%2 [L,R=301]

Block all visitors, except from some IP addresses

Sometimes you want or need to block access to all visitors, except from your own IP address. Fortunately Helicon Ape supports the REMOTE_ADDR server variable, which you can use to test the visitors IP address against.

Blocked visitors simply receive a Forbidden error message.

# Enable the RewriteEngine.
RewriteEngine On

# Deny access to everyone (all visitors), except the IP addresses 
# below. Change and 555.66.7.888 with the 
# IP addresses.
# You can use this .htaccess file on IIS in separate folders 
# to protect/secure them.
RewriteCond %{REMOTE_ADDR} !(|555.66.7.888)
RewriteRule .* / [F,L]

There are several use cases for blocking visitors with Helicon Ape. For example when you're creating your own .htaccess HTTP blacklist with Helicon Ape, or if you need to temporarily disable your website for maintenace.


Having a managed IIS module like Helicon Ape gives you the possibility to write and use powerfull .htaccess files. You can use these to secure your site by blocking access, redirect URL's or link multiple domains to subfolders in your site. But the only advantage of using .htaccess in IIS is you are using a cross platform solution. For Windows Server IIS, it's still best to use web.config files and IIS URL Rewrite Module.

Helicon Ape uses about 33% or more memory, so it's very memory consuming. Also, the Helicon Ape managed IIS module by Helicon Tech hasn't been updated in years. Be careful when using this module in your webserver.


  1. Hi Andy,

    Thank you for your comment. Something like the following should work:

    # Enable the RewriteEngine.
    RewriteEngine on
    # Rewrite hostheader through to 
    # using a RewriteProxy request.
    # Change with your domainname and 
    # with the IP address of webserver B.
    RewriteCond %{HTTP:Host} ^(?:www.)$
    RewriteCond %{REQUEST_URI} /blog(.+)
    RewriteProxy .? [H]

    You do need to know and use the IP address of in the RewriteProxy rule. But are you sure you want to proxy? Why not rewrite or redirect from to

    Note: provided as-is, not tested.
    Edit: misread original question, edited comment accordingly

    • Andy

      Thank you for your help Jan, the script works perfectly after i got a dedicate ip address for the blog site.

  2. Andy

    Hi Jan

    These are excellent examples you have provided. I’m new to this and was wondering how would i use RewriteProxy in the following situation?

    I have a website hosted by myself (, a wordpress blog hosted by another company (, however how do i proxy the wordpress content when i type in my site?

    I’m using ISAPI_Rewrite 3 from Helicon with IIS6

    Your help will be greatly appreciated!!

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