SSH Keys

system security linux ssh
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The objective of the generation and export of the SSH keys is the possibility to connect to the server without typing a login / password.


On the server, .ssh directory must be present in home directory of the user used by the client. For instance, if the client use vincent account to the connection to the server :

$ mkdir /home/vincent/.ssh


Two steps are necessary on client side to allow a connection to a distant server with SSH Keys : Generationn, Export.


You can generate SSH Keys with the following command :

$ ssh-keygen -t rsa 

If have already keys, .ssh directory in your home directory is not empty. (~./ssh/ exists)

For more security, you can add a passphrase during keys creation with command :

$ ssh-keygen -t rsa -p


There are two ways to export keys to a server :

$ cat ~/.ssh/ | ssh user@distant_host "cat >> .ssh/authorized_keys"


$ ssh-copy-id -i ~/.ssh/ user@distant_host

Now, you can connect to the server without typing a password :

$ ssh user@distant_host

Change SSH Key passphrase

You can change your ssh passphrase :

$ ssh-keygen -f ~/.ssh/id_rsa -p

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