Disable password authentication for SSH

I followed these steps (for Mac).

In /etc/ssh/sshd_config change

#ChallengeResponseAuthentication yes
#PasswordAuthentication yes

to

ChallengeResponseAuthentication no
PasswordAuthentication no

Now generate the RSA key:

ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa

(For me an RSA key worked. A DSA key did not work.)

A private key will be generated in ~/.ssh/id_rsa along with ~/.ssh/id_rsa.pub (public key).

Now move to the .ssh folder: cd ~/.ssh

Enter rm -rf authorized_keys (sometimes multiple keys lead to an error).

Enter vi authorized_keys

Enter :wq to save this empty file

Enter cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

Restart the SSH:

sudo launchctl stop com.openssh.sshd
sudo launchctl start com.openssh.sshd

Here's a one-liner to do this automatically

sed -i -E 's/#?PasswordAuthentication yes/PasswordAuthentication no/' /etc/ssh/sshd_config

The #? is an extended regular expression that matches the line whether it's commented or not. The -E switch enables extended regexp support for sed.

In file /etc/ssh/sshd_config

# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication no

Uncomment the second line, and, if needed, change yes to no.

Then run

service ssh restart

Run

service ssh restart

instead of

/etc/init.d/ssh restart

This might work.