Hydra is a parallelized login cracker which supports numerous protocols to attack. It is very fast and flexible, and new modules are easy to add. This tool makes it possible for researchers and security consultants to show how easy it would be to gain unauthorized access to a system remotely.
# sudo apt-get install hydra -y
# hydra -t 10 -V -f -l root -P wordlisst/rockyou.txt ftp://127.0.0.1
-t = How many parallel attempt at a time(1/5/10/100 ?). Don’t use too much otherwise you will get false result
-V = Show output
-f = Stop when found the password.
-l = The Username (-L for username from file)
-P = Dictionary file
To see full list of help
# hydra --help