View source for SSH Keys

With any SSH connection the user must be authenticated by ways of a password.  SSH keys contain the IP of the machine, username and a public/private key which are used for the authentication of SSH connections.

=== Create SSH keys ===
To create the SSH keys you run this command on each node;

<pre>
[root@localhost ~]# ssh-keygen -t rsa
</pre>

The output will look like this;
<pre>
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
2b:7d:e0:7c:ca:7b:46:95:fd:94:9e:55:be:c5:8d:07 root@localhost
</pre>

You do not want to enter a passphrase as you will be required to enter this for each SSH connection (defeating our purpose of no manual intervention).  

=== Copy keys ===
On each node you must copy the '''/root/.ssh/id_rsa.pub''' to the other nodes but into the file '''/root/.ssh/authorized_keys''''.  For example;

<pre>
[root@localhost ~]# scp /root/.ssh/id_rsa.pub root@otherhost:/root/.ssh/authorized_keys
</pre>

This will over write '''authorized_keys''' if it exists so you may be better off copying it to a temporary file like '''temp_key''' and then adding it into '''authorized_keys'''

[[Category: Linux]]