Use Only Key File to Login Linux Server

This is a simple guide only for Linux beginners, showing the steps to use only key file to login Linux server and disable password login.

• Assume that you are now logged as root

adduser ariel
usermod -aG sudo ariel
nano /etc/ssh/sshd_config

• Modify the following:
  PasswordAuthentication no
PubkeyAuthentication yes
  Note: If you have any .conf file in /etc/ssh/sshd_config.d/, which has any content of PasswordAuthentication yes, you can either change the value to no or simply delete the conf file(s).
• Generate key file (for the prompts just hit enter)

su - ariel
cd ~/.ssh
ssh-keygen -t rsa

• Copy publickey

cat id_rsa.pub >> authorized_keys

• Save the privatekey to local

cat id_rsa

Copy the content and paste it to your_key_name.pem in your local computer

• Restart sshd of your server

systemctl restart sshd

• On your local, change permission

chmod 400 /your/key/path/your_key_name.pem

• Login with key file

ssh -i /your/key/path/your_key_name.pem ariel@your-server-ip

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