"This guide describes how to generate and use a private/public
key pair to log in to a remote system with SSH using PuTTY. PuTTY
is an SSH client that is available for Windows and Linux (although
it is more common on Windows systems). Using key-based SSH logins,
you can disable the normal username/password login procedure which
means that only people with a valid private/public key pair can log
in. That way, there is no way for brute-force attacks to be
successful, so your system is more secure..."