Generating a SSH keypair in Linux on ESA HPC

In order to generate SSH keypair in Linux, we recommend using a command “ssh-keygen”. If system does not see this packet installed, please install the latest updates using command:

sudo apt-get update && apt-get install openssh-client

(for Ubuntu and Debian family), or

sudo yum install openssh-clients

(for CentOS and Red Hat).

After that, in terminal (in systems with graphic user interface terminal can be acquired by pressing Ctrl + Alt + T) please enter command:

ssh-keygen

(with additional flags:)

-t rsa authentication key type -b 4096 bit length (greater the value, more complicated key will be, available values: 1024, 2048, 4096; 2048 if not specified ) -C “user@server” name for identification at the end of the file -f ~/.ssh/keys/keylocation location of folder with ssh keys -N passphrase passphrase, can be ommited if user prefers connecting without additional key security

../_images/ssh1.png

Application will ask for name of the key (press Enter for defaults - id_rsa for private and id_rsa.pub for public key) and passphrase (press Enter to ignore).

../_images/ssh2.png

Next, ssh-keygen will show location, where the keys are saved, fingerprint of keypair and certain semigraphic image as expression of randomness in generating unique key.

../_images/ssh3.png

To avoid problem with rejecting files due to too open permissions, simply navigate to the folder containing both keys and enter command:

chmod 600 id_rsa && chmod 600 id_rsa.pub