Password-less login over SSH

You can login to a remote Linux server without entering password using ssky-keygen and ssh-copy-id.

ssh-keygen creates the public and private keys. ssh-copy-id copies the local-host’s public key to the remote-host’s authorized_keys file.
ssh-copy-id also assigns proper permission to the remote-host’s home, ~/.ssh, and ~/.ssh/authorized_keys.

1, Create public and private keys using ssh-key-gen on local-host

me@local-host$ ssh-keygen

Generating public/private rsa key pair.
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is:
33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9 jsmith@local-host

Step 2: Copy the public key to remote-host using ssh-copy-id

me@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host
    me@remote-host's password:

Now try logging into the machine, with

ssh 'remote-host'"

 check in .ssh/authorized_keys

Login to remote-host without entering the password

me@local-host$ ssh remote-host
Last login: Sun Nov 15 12:22:33 2008 from 191.128.6.2

me@remote-host$   [Note: You are on remote-host here]