Medusa is intended to be a speedy, massively parallel, modular, login brute-forcer. The goal is to support as many services which allow remote authentication as possible.

The author considers following items as some of the key features of this application:

• Thread-based parallel testing. Brute-force testing can be performed against multiple hosts, users or passwords concurrently.
• Flexible user input. Target information (host/user/password) can be specified in a variety of ways. For example, each item can be either a single entry or a file containing multiple entries. Additionally, a combination file format allows the user to refine their target listing.
• Modular design. Each service module exists as an independent .mod file. This means that no modifications are necessary to the core application in order to extend the supported list of services for brute-forcing.

Testing password bruteforce with Medusa , THC hydra and Ncrack showed a better result with this tool:

Speed comparison: password list of 20 entries (valid entry at #20)
FTP / Ubuntu 11.10 vsftp 2.3.2
        [1 task]    [4 tasks]    [16 tasks] 
Medusa  1:03.53     15.727         7.658     (e.g., -t 16)
Hydra     57.527    16.545         8.013     (e.g., -t 16)
Ncrack  1:00.01     24.017        15.009     (e.g., -g cl=16,CL=16)

Speed comparison: password list of 1003 entries (valid entry at #1000)
HTTP / Windows 2008 IIS 7.0
        [1 task]    [4 tasks]    [16 tasks] 
Medusa  1.390       0.803        0.626       (e.g., -v 4 -t 16)
Hydra   1.443       0.855        0.790       (e.g., -t 16)
Ncrack  3.108       3.016        3.013       (e.g., -g cl=16,CL=16)

Speed comparison: password list of 1003 entries (valid entry at #986)
SMB / Windows 2008 
        [1 task]    [4 tasks]    [16 tasks] 
Medusa  6.859       0.919        0.500       (e.g., -v 4 -t 16)
Hydra   8.216                                (doesn't handle parallel connections)
Ncrack                                       (failed to auth to test server) 

Speed comparison: password list of 10 entries (valid entry at #10)
SSH Ubuntu 11.10 OpenSSH 5.8p1
        [1 task]    [4 tasks]    [16 tasks] 
Medusa  38.039      11.943       8.067       (e.g., -v 4 -t 16)
Hydra   32.122      12.208       8.457       (e.g., -t 16)
Ncrack  30.023      27.012       24.013      (e.g., -g cl=16,CL=16)

When you plan to run a pentest you will need to have several tools for running the scan and password attack and depending on the protocol or service you want to attack you may need this tool and more.

You can read more and download this tool over here: https://github.com/jmk-foofus/medusa