Hi there, Sorry for my stupid questions. I'm new to linux and just learning. Appreciate to ur help in advance. I've done everything of the ssh part from tutorial. I made the ssh work. however there are two things that I don't understand. 1. I copied id_rsa.pub to .ssh/authorized_keys. every time when I use ssh to log in, it asks for my .pib publickey. shouldn't ask for my private key? shouldn't be public key on server side and use private key on client side for logging in? otherwise what does private key do if server side use public key and require client side for public as well? private key is not using when auth? 2. I set "PasswordAuthentication no" and "PermitRootLogin no" and run "sudo service ssh restart". why it doesn't ask for passphrase when i use key to login anymore? I thought these two command only have something to do with password login and root login. why does it make passphrase not work anymore? Kind Regards Yan