Captcha's & IP Address

I just wanted to ask. Rather then u开发者_如何学Pythonsing a Captcha or as well as using one would there be value in keeping a list of the IP address that have used the form and start to block adding if it breaks a condition like 5 per minute?

any thoughts?

thx

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This solution would block legitimate user who're posting fast - you should present a CAPTCHA to those. Bear in mind that multiple people may share an IP address via NAT.

Also, you would still get spam, but only once per IP address. Since spammers often use large botnets with thousands or millions of IP addresses, they could easily send thousands or millions of spammy messages.

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I wouldn't assume that there is a 1:1 mapping between IP addresses and people, either good people or bad people.

Many universities and large enterprises have thousands of people sat behind one HTTP proxy or NAT device. 5 per minute wouldn't be hard to hit. Some ISPs, particularly mobile ones do this too.

Conversely if someone was really looking to mess with you they probably have access to or could acquire access to a botnet and very quickly could learn the optimal rate at which to try and break your system without getting blocked.