Password-less SSH Login

Generating Keys on Source Machine

On the source machine from which you want to initiate password-less ssh connections (admin), run ssh-keygen to generate a public and private key pair.  The following is an example session showing the creation of a personal private/public key pair.

[chris@admin ~]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/chris/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/chris/.ssh/id_rsa.
Your public key has been saved in /home/chris/.ssh/
The key fingerprint is:
f6:61:a8:27:35:cf:4c:6d:13:22:70:cf:4c:c8:a0:23 chris@admin

The command ssh-keygen -t rsa initiated the creation of the key pair. No passphrase was entered (Enter key was pressed instead).  The private key was saved in .ssh/id_rsa. This file is read-only and should be kept private, no one else must see the content of this file, as it is used to decrypt all correspondence encrypted with the public key .ssh/

Adding Public Key to Target Machines

The public key is save in .ssh/  The contents of this file might look something like the following.

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEArkwv9X8eTVK4F7pMlSt45pWoiakFkZMw
WQM= chris@admin

It is one line in length.  To enable password-less ssh logins to a set of machines, slave01, slave02, and slave03, copy the .ssh/ file to all three machines and then concatenate it to the file ~/.ssh/authorized_keys on each of the three machines.  Make sure the file access permissions are correct on all the ssh files and directories. On the source machine (admin):

$ chmod 755 ~
$ chmod 700 ~/.ssh
$ chmod 600 ~/.ssh/id_rsa

On the target machines (slave01, slave02, slave03):

$ chmod 755 ~
$ chmod 700 ~/.ssh
$ chmod 400 ~/.ssh/authorized_keys