SSH is a software package that enables system administrators to securely administer their systems from a remote network with user authentication, commands, output, and file transfers being encrypted to protect against attacks in the network. While it is much more secure than common login services such as telnet, ftp, rlogin, rsh, and rcp, its default installation isn’t hardened.
This advisory covers some of the hardening measures you can take to secure ssh. For details Securing SSH