System administrators have implemented Secure Shell (ssh) to provide protected access to a remote Linux system, but don’t realize that by allowing password authentication, they are still open to brute-force attacks from anywhere on the internet. There are worms running rampant on the internet which do an effective job finding weak username/password combinations, and these are not stopped by the use of Secure Shell. We explain how to setup PuTTY private RSA keys by using PuTTYgen.exe, PuTTY.exe, Pageant.exe and other utilities. We also explain howto setup the server side to keep you Unix machine secure.