I was fortunate enough to take part in Black Hat 2011 EU where was first public presentation of Roboo the HTTP mitigator http://www.ecl-labs.org/2011/03/17/roboo-http-mitigator.html. What is less fortunate is that it can be a pain to install, mostly because of dependency on perl modules. I have tried it a few times and present my experience in here.
Get yourself roboo which comes as a nginx module written in perl. Also get nginx example configuration. Newest versions are available in github https://github.com/yuri-gushin/Roboo. Place these files to those locations
To avoid problem below modify first line of nginx.conf and change user nobody to www-data for example: Starting nginx: [emerg]: getgrnam("nobody") failed in /etc/nginx/nginx.conf:1 configuration file /etc/nginx/nginx.conf test failed
It is tempting to install nginx from reposotory but you will get error.
Starting nginx: [emerg]: unknown directive "perl_modules" in /etc/nginx/nginx.conf:10 configuration file /etc/nginx/nginx.conf test failed