how to prevent proxyusers?

[fffeee]

i have a platform where i give away free bitcoins.. (it is allowed to order some coins every 12 hours..)

is there a good way to prevent proxyusers or worse.. proxybots!??

[hamdi]

use captchas
use cookies

maybe check the IP address for typical open proxy ports

[Tuxavant]

I use random short urls, captchas, pre-programed campaigns, and random release times to prevent abuse at Coin4.me. It's not perfect, but it at least levels the playing field.

Example: http://coin4.me/pizza

[gweedo]

I know you can detect tor proxies and just kill those off, but some people only will with use the web so you have to accept that you could be cutting those people out.