Dave Burke : Freelance .NET Web Developer specializing in Online Communities

Children of a Lesser CAPTCHA

My CAPTCHA Add-on for Community Server 2.1 is now available in my Files area Community Server Add-Ons Folder

What can I say, I used CAPTCHA for almost two years now and have never had to think about Spam.  CAPTCHA puts the burden on my friends who are good enough to add comments on this site (and your friends who add comments to your site), but this CAPTCHA displays a clearly visible 3-digit code and is a small request to make for the benefit of being completely Spam-free. 

There have been significant improvements made in Spam prevention, no question, and I can begin to accept the idea that my embrace of CAPTCHA may be coming to an end.  (Wow, that was quite a collective gasp!)  Releasing a CAPTCHA Add-On also makes me feel like I'm dissing one of the best developers and greatest guys that I know, Jose Lema, by not using the rock solid Spam Blocker he designed for Community Server.  There's no question the CS Spam Blocker works and with additions like those added just today, in fact, with Askimet and 3rd party integration (thanks primarily to the work of Thomas Freudenberg), you can't find better Spam Prevention.  But darn it, I'm an oldster who can't even spell "threashold" let alone configure for it, and I never could understand the difference between a "bad word" and a "forbidden word."  Bad words have four letters in them and forbidden words start with an "F" as far as I know.  On the other hand, I do understand asking for 3 numbers to make Spam a non-issue.

I just searched my blog and found the description of my first CAPTCHA mod back in October, 2004.  That was for dotText, and seems like such a long time ago.  CAPTCHA mods for CS 1.0, 1.1 and 2.0 followed, and now CAPTCHA for CS 2.1.   You could say I'm like Sam Weber in The Big Chill, throwing a spaghetti noodle against the wall in Harold and Sarah Cooper's kitchen to test whether its done or not.  Meg (Mary Kaye Place) says to Sam, "Do you mean after all these years that's the only thing you know how to make?" to which Sam Weber replies, "But I've improved on it!"

This tribute-to-sticky-spaghetti-noodle CAPTCHA Add-On is, incredibly, my first Drop and Pop version of CAPTCHA for Community Server.  Every previous version required changing the source.  Bad.  This version has a drop-in \bin\DLL, a drop-in \blogs\.ASPX file, and some HTML snippets for the appropriate .ASCX files.  So the bad news is that there's another Community Server CAPTCHA Mod in the world; the good news is that I'm getting better at it. heh.

Speaking of getting it better, a big thank you to The Wizard, Rick Reszler, who helped me work out the kinks in supporting the new CS 2.1 themes like Paperclip that inherit from \default View controls and for improving the installation process in general. 

Comments (11) | Post RSS RSS comment feed

Posted on 8/30/2006 9:29:00 PM by Dave Burke
Categories: Community Server
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Comments (11) -

8/30/2006 10:57:56 PM Permalink

One day you'll leave this CAPTCHA finally, I'm sure Wink

Although I haven't used CAPTCHA so far but don't get any public spam since there are great tools to block them in hand.  I just get them as Spam or Possible Spam so I think it's time to say using CAPTCHA or CS spam blocker add-ons don't have any difference except that CAPTHCA isn't user friendly Smile

Keyvan Nayyeri |

8/31/2006 12:30:20 AM Permalink

You've inspired me, Dave. I've downloaded those new spam rules and, having enabled the "duplicate" and "post length" rules, I've disabled ReverseDOS. We'll see how well it works!

mabster |

8/31/2006 9:07:03 AM Permalink

Set it and Forget it! Smile

The Wizard |

12/4/2006 7:44:49 AM Permalink

I have added the CAPTCHA and it seems to be set up correctly except I just get a red X where the image of numbers is supposedto be. Any ideas why? I have the 'JpegImage.aspx' file in my /blogs folder and the 'DaveBurke.CS21.Captcha.dll' file in my /bin folder. I have modified all 4 of the other files and it just isn't showing up. I am running CS 2.1 with .NET 2. You can see an example here www.jeffandtami.com/.../My-First-Post.aspx
Thanks for the help.

Jeff |

12/4/2006 8:46:35 AM Permalink

Hi, Jeff!  It's because the CAPTCHA control assumes /blogs is in your site root directory.  It's looking for   It will work on your production blog.  You can change the commentform skin for the sample weblog to use /cstest/blogs/jpegimage.aspx and it would work.

daveburke |

12/8/2006 11:03:43 AM Permalink

Can we make the captcha image more difficult to read. Now it is very easy to read the letters.

stephen |

12/8/2006 11:31:19 AM Permalink

Was that a joke, Stephen?  HA!  I HATE difficult to read captcha images.  All I can say is that the captcha I've been using as you see here over the last two years has never been cracked by a machine.

You can make the numbers more difficult to see by changing the values in the matrix.Translate(float, float) function in the CaptchaService.GenerateImage() method.

daveburke |

12/8/2006 11:54:37 AM Permalink

No. It is not a joke. Since there are some softwares which look for easy to read code, my boss wants me to skew the image a little and make it more difficult to read. How can we make it skew?  I changed the method and it makes it difficult to read, but if you can help me with the skewing, I appreciate it. anyway thanks for the prompt reply.Your site is awesome!!

stephen |

12/8/2006 1:37:50 PM Permalink

Thanks for the kind words, Stephen.

The best way to distort the numbers if you really need to do it is to twist the rectangular display.  Look for the code in GenerateImage() that looks like this.  Add the +/- # to the end of each line as you see here.  Twist as much as you like.

PointF[] points =
{
  new PointF(this.random... / v - 5),
  new PointF(rect.Width... / v + 10),
  new PointF(this.random.Next... v + 5),
  new PointF(rect.Width - this.random... / v - 7)
};

daveburke |

1/23/2007 2:20:34 PM Permalink

Installed and works like a charm. Thanks Dave!

Steve

steveso |

1/23/2007 2:35:01 PM Permalink

Cheeseflavor!  Great to hear it.  I'm wondering if I'll need a Community Server 2007 CAPTCHA control?  I might have to bite the bullet and figure out CS's Spam Filter settings. Smile  Thanks for the comments.

daveburke |


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