SSH: Copying public key to remote server

Show that there is no public key for this SSH key:

ssh-keygen -l -f ~/.ssh/id_rsa

Generate public key from the private key provided with the -f option:

ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub

Check again:

ssh-keygen -l -f ~/.ssh/id_rsa

Copying to public key to remote server (Linux):

ssh-copy-id username@remote_host

Copying to public key to remote server (Windows):

cat ~/.ssh/id_rsa.pub | ssh username@remote_host "cat >> ~/.ssh/authorized_keys"

Now you can login without password:

ssh username@remote_host