ssh-keygen: password-less SSH login

ssh-keygen is used to generate that key pair for you. Here is a session where your own personal private/public key pair is created:

cantin@sodium:~> ssh-keygen -t rsa Generating public/private rsa key pair. Enter file in which to save the key (/home/cantin/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/cantin/.ssh/id_rsa. Your public key has been saved in /home/cantin/.ssh/id_rsa.pub. The key fingerprint is: f6:61:a8:27:35:cf:4c:6d:13:22:70:cf:4c:c8:a0:23 cantin@sodium In this case, the content of file id_rsa.pub is ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEArkwv9X8eTVK4F7pMlSt45pWoiakFkZMw G9BjydOJPGH0RFNAy1QqIWBGWv7vS5K2tr+EEO+F8WL2Y/jK4ZkUoQgoi+n7DWQVOHsR ijcS3LvtO+50Np4yjXYWJKh29JL6GHcp8o7+YKEyVUMB2CSDOP99eF9g5Q0d+1U2WVdB WQM= cantin@sodium

It is one line in length.

Its content is then copied in file .ssh/authorized_keys of the system you wish to SSH to without being prompted for a password.