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2.4.2. Configure SSH

SSH is a convenient and secure way to copy files and perform commands remotely. For the purposes of this guide, we will create a key without a password (using the -N “” option) so that we can perform remote actions without being prompted.


Unprotected SSH keys, those without a password, are not recommended for servers exposed to the outside world.
Create a new key and allow anyone with that key to log in:
Creating and Activating a new SSH Key
# ssh-keygen -t dsa -f ~/.ssh/id_dsa -N ""
Generating public/private dsa key pair.
Your identification has been saved in /root/.ssh/id_dsa.
Your public key has been saved in /root/.ssh/
The key fingerprint is:

The key's randomart image is:
+--[ DSA 1024]----+
|==.ooEo..        |
|X O + .o o       |
| * A    +        |
|  +      .       |
| .      S        |
|                 |
|                 |
|                 |
|                 |

# cp .ssh/ .ssh/authorized_keys
Install the key on the other nodes and test that you can now run commands remotely, without being prompted
# scp -r .ssh pcmk-2:
The authenticity of host 'pcmk-2 (' can't be established.
RSA key fingerprint is b1:2b:55:93:f1:d9:52:2b:0f:f2:8a:4e:ae:c6:7c:9a.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'pcmk-2,' (RSA) to the list of known hosts.root@pcmk-2's password:                           100%  616     0.6KB/s   00:00
id_dsa                               100%  672     0.7KB/s   00:00
known_hosts                          100%  400     0.4KB/s   00:00
authorized_keys                      100%  616     0.6KB/s   00:00
# ssh pcmk-2 -- uname -npcmk-2
Figure 2.22. Installing the SSH Key on Another Host