Introduction:
Secure Shell (SSH) is a cryptographic network protocol that provides a secure way to access and manage remote servers. SSH keys offer a more secure and convenient alternative to password-based authentication. In this article, we will walk you through the process of setting up SSH keys on Ubuntu 22.04.
Step 1: Check for Existing SSH Keys
Before generating new SSH keys, it’s important to check if you already have any existing keys. Open a terminal and execute the following command:
ls ~/.ssh
If you see files named id_rsa and id_rsa.pub or any other key files, it means you already have SSH keys. You can skip to Step 4 to configure your existing keys.
Step 2: Generate a New SSH Key Pair
To generate a new SSH key pair, use the following command in the terminal:
ssh-keygen -t rsa -b 4096
You will be prompted to provide a location to save the key pair. Press Enter to accept the default location (~/.ssh/id_rsa). You can also specify a custom path if desired.
Next, you’ll be prompted to enter a passphrase. While optional, setting a passphrase adds an extra layer of security to your key pair. Remember to use a strong, unique passphrase and keep it safe.
Step 3: Add the SSH Key to the SSH Agent
The SSH agent is a program that holds your private keys in memory, allowing you to authenticate with the server without typing your passphrase every time. Start the SSH agent by running the following command:
eval "$(ssh-agent -s)"
Next, add your private key to the SSH agent using the following command:
ssh-add ~/.ssh/id_rsa
If you set a passphrase in Step 2, you’ll be prompted to enter it.
Step 4: Configure SSH Access on the Server
To enable SSH access using your SSH key, you need to copy your public key to the remote server. Assuming you already have SSH access to the server, use the following command to copy your public key:
ssh-copy-id user@server_ip
Replace user with your username and server_ip with the IP address or domain name of the remote server. You will be prompted to enter your password for authentication.
If you don’t have SSH access yet, you can manually copy the contents of your public key file (~/.ssh/id_rsa.pub) to the ~/.ssh/authorized_keys file on the remote server. Use the following command to open the authorized_keys file:
nano ~/.ssh/authorized_keys
Paste the contents of your public key file, save the changes, and exit the editor.
Step 5: Test SSH Key Authentication
To verify that SSH key authentication is working correctly, run the following command:
ssh user@server_ip
Replace user with your username and server_ip with the IP address or domain name of the remote server. If everything is set up correctly, you should be logged in without being prompted for a password.
Conclusion:
You have successfully set up SSH keys on your Ubuntu 22.04 system. By using SSH keys for authentication, you have enhanced the security and convenience of remote server access. Remember to keep your private key safe and use SSH key-based authentication wherever possible to protect your systems from unauthorized access.
Nilesh R. Agrawal 