Captcha recommendations and alternatives

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Forbairt

Forbairt

Teaching / Designing / Developing
Tom said:
What are the best captcha's or alternatives out there to help fight spam?
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What system are you using ? language ... ? ... or is it for a custom build ?
 
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Tom

Member
Php and Javascript mostly but really any recommendations no matter what technology they use.

Came across a nice page with some tips here AS Workshop » The CAPTCHA Alternatives

this tip sounds good... quoted from above page

I am surprised no-one has mentioned a variation on the session idea where you record the time the form was loaded. Then on the post you calculate the time difference and if its less than say 5 seconds you ignore it as spam. Of course spam bots could easily adjust for this by building in a delay, but imagine if we all did this forcing all spam bots to work more slowly we could reduce the total amount of spam for everyone. Since implementing such a system about a week ago I have not had a single item of spam get through.
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I just checked a lot of spam I've been receiving and unfortunately it seems to be 30secs or so apart, so either bots are now going slower to mimic humans or the spam was entered manually.
 
mneylon

mneylon

Administrator
Staff member
One of the things I do on here is check against DNS blacklists.

If someone's IP is listed in SpamHaus they're automatically banned when they try to signup :)

It means that the amount of junk posted is significantly lower!
 
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CiaranR

Weeno Ltd + Skimlinks.com
I just wrote a custom challenge based one and it easily the best, simply and box to your reg page saying "What is 2 plus Three?" the in the reg page check for 5 or Five or five
 
Forbairt

Forbairt

Teaching / Designing / Developing
They are good to a certain extent ... you need a fairly decent sized question base ... if you make it too difficult it will disuade users ...

some of the bots are already able to handle some of the challenges ...
 
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Tom

Member
I don't really like the idea of asking questions or picking images, I worry that less web savvy folk might read it and think "What the heck is this? Why is this website asking me a silly question? What is 2+2? Or what year is it? Or pick the elephant." Even if you explain why I still don't think it looks the best, especially for certain types of sites.

Standard captchas have been around longer and I imagine more people would be used to them. Imo I think they look better than asking a silly question too.

I wonder how an animated gif or flash captcha might work, I haven't seen any of these in action. Surely they would be very hard for a bot to recognize and nearly everyone has flash these days.
 
Forbairt

Forbairt

Teaching / Designing / Developing
georgiecasey said:
There are a few animated captchas. Georgie Casey » Blog Archive » Most annoying captchas ever
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Oh god ... I don't even think I'd get them right :D

georgiecasey said:
They'd be easy enough for a bot to do if they could do static captchas. Captcha solvers are highly advanced, nothing really stopping them if the volume is there. So I'd say just use a unique captcha and the spammers wouldnt be bothered writing something to solve it.
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I think the problem is bots can identify the captcha on your page ... its not whether you do a custom captcha or not ...

possibley saying please pick the first letter and last number from this image might work ... again you're making the user have to think about it all and as Tom said .. these days .. people are used to Catchas ...
 
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Tom

Member
Yikes that animated captcha is insane :) I was thinking of the characters slowly moving up and down in a wave like motion or something that wouldn't be so hard on the eyes. Maybe even slowly animating inverting colour changes or something.
 
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TheMenace

New Member
Tom said:
I don't really like the idea of asking questions or picking images, I worry that less web savvy folk might read it and think "What the heck is this? Why is this website asking me a silly question? What is 2+2? Or what year is it? Or pick the elephant." Even if you explain why I still don't think it looks the best, especially for certain types of sites.
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The idea of a Captcha at all isn't particularly pretty. But it's better than your customers or clients getting emails of links to pictures of gigantic black cocks.

I implemented a simple logic test on one of my sites and my own blog (for example here and here) and it's almost completely erradicated the amount of filth being sent from my forms.

Tom said:
I wonder how an animated gif or flash captcha might work, I haven't seen any of these in action. Surely they would be very hard for a bot to recognize and nearly everyone has flash these days.
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I built a Flash-based Captcha (using ASP classic) a good while back. It was used on one of my friend's old forums and really worked a treat. Feel free to download it here.
 
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