View Full Version : Preventing Web Form Spam

28th March 2006, 09:44 PM
Hi all,

Just wondering if anyone has any clues on preventing web forms being spamed by computers...

Ultimately, the best thing would be a page with one of those kind of garbled looking images contining an alpha numeric code, which the user has to enter, but I'm sure this would be a costly exercise, probably involving secure servers etc.

The scenario is a web form to submit links to a links page, but it is getting hit with undesireable links all too often.

Is there some sort of cgi or php script which might solve the problem? Or a better way of having links submitted?

Any clues appreciated.


28th March 2006, 09:49 PM
DO a google, I am sure you will find some php classes to do the garbled image on your forms so that it has to match each time..

28th March 2006, 10:31 PM
Thanks purana, I had no idea what I should be searching for on google.... Haven't done any php up until very recently, and even then it has only been installing/setting up a blog with pre written code.

Google of "php classes" brought up a link to this:

Looks like exactly what I was after, cheers

29th March 2006, 05:15 AM
There are a few methods but the most reliable IMO is to use cookies or sessions to restrict a user from submitting a form more than once.

Another method could be to set a cookie with the time a form was submitted, then you could restrict it to being submitted once every hour, half hour, 10 mins or whatever. This would work kind of like a flood control.

There are downsides to all methods, you need to weight up your concern for usability with the need for form protection.