How to disable password authentication?

To disable password authentication for SSH, you can modify the SSH server configuration file. Here’s how to do it:

Open the SSH configuration file with a text editor (using sudo for superuser privileges):
```
sudo nano /etc/ssh/sshd_config
```
Find the line that says:
```
PasswordAuthentication yes
```
If it doesn't exist, you can add it.
Change it to:
```
PasswordAuthentication no
```
Save the changes and exit the editor.
Restart the SSH service to apply the changes:
```
sudo systemctl restart sshd
```

This will disable password authentication, requiring users to use key-based authentication instead. If you have any further questions, feel free to ask!