connect to an Ubuntu server via SSH without a password

To connect to an Ubuntu server via SSH without a password, you need to set up SSH key-based authentication. The steps are:

1. Generate an SSH key pair on your local machine:

ssh-keygen

This will create a public key (id_rsa.pub) and a private key (id_rsa) in the ~/.ssh/ directory.

1. Copy the public key to the remote Ubuntu server:

ssh-copy-id remote_username@server_ip_address

This will append the public key to the ~/.ssh/authorized_keys file on the remote server.

1. Disable password authentication on the remote server by editing the /etc/ssh/sshd_config file:

sudo nano /etc/ssh/sshd_config

Find the lines:

PasswordAuthentication yes
ChallengeResponseAuthentication yes

and change them to:

PasswordAuthentication no 
ChallengeResponseAuthentication no

Then save the file and restart the SSH service:

sudo systemctl restart ssh
```[1][3][5]

After completing these steps, you should be able to log in to the remote Ubuntu server using SSH without entering a password.[1][2][3]