Hi there,
i used the method to generate PKI keys using the description from tennis.ecs.umass.edu/~czou/linux/backupSSH.html.
The command to create public key and private key is basically ssh-keygen -t rsa. After that I then copy the public key to the server that I want to connect to. The purpose of me doing this is that I want to connect to server directly therefore without entering any password. Actually, i managed to connect to the server directly for one server without entering the passwd by using this method. But when i tried the same method with another server I had to key in my passwd. I was just wondering, are there any settings in the server which may have caused this method not to work? Any help will be appreciated.thx

It's possible that the server has disabled public key authenticagtion or that its SSH server software doesn't support it (older versions of some ssh daemons do not). Can you check the server's sshd.conf file and what version of SSH it'srunning (if you use -v to ssh it should print out the server's banner).