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Can somebody please assist me, i am building a personal web application
in C# and i want to include a Captcha.I have decided to use a number sequence, as in "2,4,_,8". The user must fill in the missing value. Also, the placeholder must change on each attempt. I also want the Captcha to monitor unsuccessful IP(i.e Flag them). Thanks in advance
Updated 29-Sep-11 7:26am

there is already a ASP.NET server control for this called MScaptcha. its a free control. You can download its dll from the following site[^]

You will get proper documentation, regarding how to use it.

Still for youe help, belowgiven are brief steps how to implement it.

Download the dll and add its refrence to your project and then do the following.


<add verb="GET" path="CaptchaImage.axd" type="MSCaptcha.CaptchaImageHandler, MSCaptcha"/>


//In  Aspx page or in user control

<%@ Register Assembly="MSCaptcha"Namespace="MSCaptcha" TagPrefix="cc1" %>

<cc1:CaptchaControl ID="ccJoin" runat="server" CaptchaBackgroundNoise="none" CaptchaLength="5" CaptchaHeight="60" CaptchaWidth="200" CaptchaLineNoise="None" CaptchaMinTimeout="5" CaptchaMaxTimeout="240" />

///C# Code

Button click event


  if (ccJoin.UserValidated)
//submit form
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