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This procedure allow to log-in to a ubuntu server with openssh without writing the password every time you access.

Generation of the key:

client$ mkdir ~/.ssh client$ chmod 700 ~/.ssh

client$ ssh-keygen -q -f ~/.ssh/id_rsa -t rsa

Enter passphrase (empty for no passphrase): …

Enter same passphrase again: …

Key protection on the client:

client$ chmod 700 ~/.ssh

client$ chmod go-rwx ~/.ssh/*

Copy of the public key on the server:

client$ scp ~/.ssh/id_rsa.pub <user>@<server>:

Configuration of the public key on the server:

server$ mkdir ~/.ssh

server$ chmod 700 ~/.ssh

server$ cat ~/id_rsa.pub >> ~/.ssh/authorized_keys

server$ chmod 600 ~/.ssh/authorized_keys

server$ rm ~/id_rsa.pub

The command to be executed must be cat ~/id_rsa.pub >> ~/.ssh/authorized_keys and not with a single > wich will overwrite other public keys just present on the server.