Captcha to view forum

[00pavan00]

Hello all my forum getting brute force attacks since two day all my users passwords are mostly secured but due to using of 500 bots at a time bandwidth goes down so some one please make a plugin as follows.

When user open the forum the plugin need to check the stopforumspam, if user ip is matches with stopforumspam database then user need to enter recaptcha to access the forum can some one please do it this is really helpful plugin.

OR

captcha is compulsary to view forum once user enter the captcha he can access forum and user no need to enter captcha again until selected number of days.Thanku