thc-hydra
Shows how easy it would be to gain unauthorized access to a system
...This tool is a proof of concept code, to give researchers and security consultants the possibility to show how easy it would be to gain unauthorized access from remote to a system. There are already several login hacker tools available, however, none does either support more than one protocol to attack or support parallelized connects. It was tested to compile cleanly on Linux, Windows/Cygwin, Solaris, FreeBSD/OpenBSD, QNX (Blackberry 10) and MacOS. However the module engine for new services is very easy so it won't take a long time until even more services are supported. ...