Only allow captcha solutions from IP which the captcha was given to
Title
Only allow captcha solutions from IP which the captcha was given to
Short, concise description of the idea
Only allow captcha solutions from the IP which the captcha was given to
Full description of the idea
If you're not aware, there are a number of sites that will get humans to solve captchas for you for $2 per 1,000. I suspect the way lj is using recaptcha.net allows these people to sell pre-solved captchas to anyone wishing to spam any site using recaptcha.net. (I know they sell pre-solved captchas for myspace, for example.)
This problem can be reduced by only allowing captcha solutions from the IP the captcha was originally given to.
If the image of the captcha was downloaded from one IP, don't allow another IP to use it for verification just because they have solved it correctly.
An ordered list of benefits
- Less spam.
- A little more load on lj servers?