When managing a Linux Virtual private server (VPS), security is one of the highest priorities. One key method to enhance server security is to disable password login for Secure Shell (SSH). This method compels users to utilize more secure authentication methods such as public and private keys, significantly reducing the risk of brute force attacks and securing your data against unauthorized access.
Why Disable Password Login for SSH
- Enhanced Security: Key-based authentication is more secure than traditional passwords because potential attackers cannot easily guess or crack the private key.
- Mitigation of Brute Force Attacks: By disabling password login, you eliminate the possibility of brute force attacks attempting to guess a user's password.
- Reduced Administrative Overhead: Managing keys is simpler than regularly changing and managing complex passwords for each user.
How to Disable Password Login
1. Generate SSH Keys
Before disabling password login, ensure you have an alternative authentication method set up, such as SSH keys. You can generate a key pair using the following command on your local machine:
ssh-keygen -t rsa -b 4096
Upload Public Key to the Server
After generating SSH keys, you need to upload the public key to the server. You can do this using the ssh-copy-id command, like so:
ssh-copy-id username@your_server
3. Configure SSH Daemon
Now that you have the public key uploaded to the server, it's time to configure the SSH daemon to disallow password login. This is done by editing the SSH configuration file, typically located at /etc/ssh/sshd_config.
Open this file in a text editor and make the following changes:
PasswordAuthentication no
ChallengeResponseAuthentication no
UsePAM no
After making the changes, save the file and restart the SSH service:
sudo systemctl restart sshd
Testing the Configuration
Before disconnecting, it's crucial to test whether you can still connect to the server using SSH keys. Try to connect to the server using the new key from your local machine:
ssh -i /path/to/your/private_key username@your_server
If you can successfully log in, it indicates that the configuration was successful, and password login has been disabled.
By disabling password login for SSH and transitioning to key-based authentication, you significantly enhance the security of your Linux VPS. This step is one of many in securing your server, but it's a fundamental and highly recommended practice. Always ensure you have a backup access method to the server in case of issues with key-based authentication.
