##generate rsa-public-key at client PC with 2048 bit.
#ssh-keygen -t rsa -b 2048
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.
#less /root/.ssh/id_rsa.pub
add to SSH-SERVER as
#vi /home/user/.ssh/authorized_keys
ssh-rsa yourkey
Then test login with
#ssh ssh_server_ip -luser
