To enforce HTTPS in IIS, first install and enable the URL Rewrite module via Server Manager under Role Services, then create a redirect rule in the web.config file to redirect all HTTP traffic to HTTPS with a 301 permanent redirect, and finally test the configuration across multiple URLs to ensure proper functionality; optionally, set up server-level redirects for broader application. Begin by confirming the URL Rewrite module is installed and enabled, either during setup or through your hosting provider if in a shared environment. Next, configure the rewrite rule in the section of your web.config to match all requests, check if HTTPS is off, and redirect to the HTTPS version using {HTTP_HOST} and {R:1} placeholders. After implementation, use tools like curl, Postman, or browsers to verify that all variations of your site—including root, www, and subpages—redirect correctly without loops or mixed content issues, ensuring your SSL certificate is valid. Optionally, apply the redirect at the server level via IIS Manager for multiple sites, noting that these rules affect all hosted sites unless overridden in individual web.config files. Properly configured, this approach secures traffic effectively while maintaining control and scalability.

Switching from HTTP to HTTPS is a standard practice for securing websites, and IIS (Internet Information Services) offers a straightforward way to enforce this redirect. If you're managing a site on IIS and want to make sure all traffic goes through HTTPS, here's how to do it effectively without overcomplicating things.

Install and Enable the URL Rewrite Module

Before setting up the redirect, you need the URL Rewrite module installed in IIS. It’s not enabled by default, so check if it’s available:

• Open Server Manager
• Go to Manage > Add Roles and Features
• Under Role Services, ensure URL Rewrite is checked

If it's already installed, open IIS Manager and look for the URL Rewrite icon under the site or application level.

Note: If you’re using a shared hosting environment, contact your provider — they might need to install it for you.

Once enabled, you can start creating rules that will handle the actual redirection logic.

Create a Redirect Rule Using Web.config

The most common and maintainable way to implement an HTTP to HTTPS redirect in IIS is through the web.config file. This method applies the redirect at the application level and keeps everything version-controllable.

Add or modify the <system.webserver></system.webserver> section in your web.config with the following rule:

<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="HTTP to HTTPS Redirect" stopProcessing="true">
          <match url="(.*)" />
          <conditions>
            <add input="{HTTPS}" pattern="off" ignoreCase="true" />
          </conditions>
          <action type="Redirect" url="https://{HTTP_HOST}/{R:1}" redirectType="Permanent" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

What this does:

• Matches any incoming request ((.*))
• Checks if HTTPS is off
• Redirects to HTTPS version of the same URL with a 301 Permanent redirect

This setup works well for most ASP.NET and static HTML sites hosted on IIS.

Test the Redirect Across Different URLs

After applying the rule, test it thoroughly. Use tools like curl, Postman, or just a browser to hit several variations of your site:

• http://example.com
• http://www.example.com
• http://example.com/some-page

Make sure each one redirects cleanly to its HTTPS counterpart. Also, check that:

• The redirect doesn't cause loops
• Mixed content issues don’t appear after redirecting
• Your SSL certificate is valid and properly configured

A good practice is to use Google Search Console or Screaming Frog to scan your live site and verify that all internal links are now pointing to HTTPS versions.

Optional: Set Up Redirect at Server Level

If you manage the server directly and want to apply the redirect across multiple sites, you can configure the rule at the server level in IIS Manager:

1. Open IIS Manager
2. Select the server node (not a specific site)
3. Double-click URL Rewrite
4. Click Add Rule(s) in the right panel
5. Choose Blank Rule and set it up similarly to the web.config version

Keep in mind that server-level rules affect all sites unless explicitly overridden in their own web.config files. So be careful when applying broad rules — test before pushing to production.

That’s basically it. Once the redirect is working, you can focus on other security improvements like HSTS headers or content security policies. But getting HTTP to HTTPS redirect right in IIS? Not too bad once the URL Rewrite module is in place.

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