Knowledgebase

SSH server in most systems is by default configured to allow public-key authentication. The method will enable you to use your public and private key pair to log in to an SSH server without using a username.

When you are using public-key authentication in your server, then you can't ssh from another server to your server .When you try to ssh from another server It shows like this:-

Steps to disable public key authentication in SSH:

1.Login to your server via ssh.

2.Open SSHd configuration file with any editor. 

• $ sudo vi /etc/ssh/sshd_config

3.Then search for PubkeyAuthentication and set the option to yes(for enabling public key authentication) or no(to disable public key authentication).in Vi editor for searching  the word "PubkeyAuthentication" enter "/" and type PubkeyAuthentication . Or in nano editor CTRL+w.

• PubkeyAuthentication   no.

4.Then Enable Password Authentication. For enabling password authentication search the word PasswordAuthentication 

then remove # on this line 

• PasswordAuthentication   yes.

             

        And also comment (put #) on line 

• PasswordAuthentication   no.

5. And also search the word ChallengeResponseAuthentication and disable it by adding no.

6. Then save and exit the editor.

7.Then restart ssh service by the following command

• sudo systemctl restart sshd

8. Now you have successfully disabled public-key authentication.