This is a small application built to test the performance of a http authentication system using a lot of concurrent connections. It can also be used to try lots of password against a http server. It is capable of using up to 1024 (or more using multiple processes). However with this amount it is capable or reducing internet connections to a crawl and also greatly increasing the load on the server.
You can download it from the following link: https://packetstormsecurity.com/files/download/109278/brute-http-2012-01-30.c
Source: https://packetstormsecurity.com/files/109278/HTTP-Brute-Force.html