How to Setup SSH Keys in Linux

SSH (Secure Shell Protocol) allows you to securely transfer data and files between two computers on a network or over internet. It requires password-based or key-based authentication to allow communication between two computers. In this article, we will learn how to setup SSH keys in Linux.

How to Setup SSH Keys in Linux

Here are the steps to setup SSH keys in Linux.

1. Create SSH keys in Linux

The first step is to generate SSH keys in Linux. For this purpose, open terminal on your local computer and run the following command.

$ ssh-keygen

If you see any prompts, enter y to proceed. You will be asked to enter passphrase, which is optional. If you don’t want to use passphrase, just hit enter to proceed, and once again to confirm the passphrase.

Run the following command to check if the .pub file has been created as a output of SSH key generation.

$ ls -l ~/.ssh/id_*.pub

2. Adding SSH Key to Remote Server

Next, you need to add the key file generated above to your remote server. You can do this using ssh-copy-id command on your local system. This command is pre-installed in almost every Linux system. But for this purpose, you must have password-based access to your remote server. If that is the case, run the following command to securely copy the key file to remote server. In the following command, replace user with your remote username and ip-address with the IP address of remote server.

$ ssh-copy-id user@ip-address

You will be prompted to enter remote user’s password. Enter it to copy the key files to remote server.

3. Login to Server with SSH keys

Run the following command to login to your remote server with SSH keys. Replace user with your remote username and ip-address with the IP address of remote server below.

$ ssh user@ip-address

You will be prompted for remote user’s password. Enter it to login.

4. Disable password-based authentication

Now that you are able to authenticate via SSH keys, it is advisable to disable password-based authentication in SSH. For this purpose, login to SSH server with the above command.

$ ssh user@ip-address

Once you have entered the password and logged in, run the following command to open SSH config file.

$ sudo vi /etc/ssh/sshd_config

Once you have opened SSH configuration file, change the following line

PasswordAuthentication yes

PasswordAuthentication yes

If ‘PasswordAuthentication no’ is commented, then remove # at its beginning to uncomment it.

Also change the following line

ChallengeResponseAuthentication yes

ChallengeResponseAuthentication no

Restart SSH service with the following command.

$ sudo systemctl restart sshd

In this article, we have learnt how to create SSH keys to login to remote server via SSH protocol.

How to Setup SSH Keys in Linux