Varnish 3 - Memcached - with Captcha in C++, with pcre (or equivalent) to detect spam/hackers

Varnish 3 - Memcached - with Captcha in C++, with pcre (or equivalent) to detect spam/hackers client -> Varnish -> C++ -> memcached sessions+http url (hit rate) if (hit rate > 30){ activate captcha; } client verifies captcha, clear information from memcached else block client for 3 days. please give me the quote for this.