Super-Networking Blog

One of the big things a lot of people are doing these days is SEO or search engine optimization. I am not planning on going over a comprehensive guide for SEO right now but as I run into them in my own job I will post them here.

One of the more recent tasks I had was setting up a different robots.txt for our http site vs our https site. It is the same content but Google indexes them as two different copies of the content. Google then penalizes your site for duplicate content. Well you setup your robots.txt file to exclude the files and directories you want from the bots but it doesn’t help the http vs http. Both protocols will use the same robots.txt file and so you will end up with duplicate content in Google’s index.

Here is how to solve this problem when you are running IIS 6.0 on a Windows 2003 server. You will need to also be running ASP .Net 2.0 for this solution to work. You might be able to get this to work on other platforms but I have not tested them. What we will be doing here is creating a dynamic robots.txt file, it is only one file but it will display different results depending on if you connect with http or https.

1) Create your robots.txt file:

<%@ WebHandler Language="C#" Class="MyNamespace.robotshandler" %>

using System;
using System.Web;

namespace MyNamespace {

    public class robotshandler: IHttpHandler {

        public void ProcessRequest (HttpContext context) {

            context.Response.ContentType = "text/plain";
            context.Response.Write("User-agent: *\n");

            if (context.Request.ServerVariables["Https"]=="off"){
                // HTTP
                context.Response.Write("Allow: /\n");
                context.Response.Write("Disallow: /MyDisallowedDirectory/\n");
            } else {
                // HTTPS
                context.Response.Write("Disallow: /");
            }
        }

        public bool IsReusable {
            get {return false;}
        }
    }
}

2) IIS needs to have .txt files passed through ASP .Net

- Open IIS and right click on your website and bring up the properties screen

- Go to Home Directory > Configuration. You will be on the Mappings Tab.

- Locate the ASPX item and click Edit - Copy the path in the Executable Field and cancel out of that window.

-Cancel

-Click “Add”

-Populate the Executable path with the value you copied in the last section

-Extension “.txt”

-Enter “GET” in the “Limit To” field

-Save and Exit

3) Need to modify web.config to process the .txt correctly

-Add the following under system.web:  (Look for these sections in your web.config, most likely don’t have to add the httphandler tags because they will be in there already then just add the lines inside them.)

<httpHandlers>

<add path=”/robots.txt” verb=”GET” type=”System.Web.UI.SimpleHandlerFactory” />

<add path=”*.txt” verb=”GET” type=”System.Web.StaticFileHandler” />

</httpHandlers>

<buildProviders>

<add extension=”.txt” type=”System.Web.Compilation.WebHandlerBuildProvider” />

</buildProviders>

Make sure your new robots.txt file is in your root folder for your website and everything should be good to go. Try your website out with http then https and it should be different. You will have to modify the robots.txt file to exclude what folders and files you want.