Due to the fact that Apple OS-X is based on the Unix operating system, there are already tools installed on your Mac to access SSH, albeit, not with a graphical interface like PuTTY.
To access the Terminal application on your Mac, select the Go option from the main menu bar and select the Utilities menu. From there, select the Terminal Application.
prompt, type the following:
You will then be prompted for your password, enter this now. You may also be prompted to confirm authenticity of the RSA key. If the appears, follow the on-screen instructions on what to do. From here, you can access your server with SSH via Mac OS X Terminal.