Key-based authentication in Linux CLI - Mini Project: Build & Apply

Key-based authentication

📖 Scenario: You want to securely connect to a remote server without typing your password every time. Key-based authentication lets you do this by using a pair of keys: a private key on your computer and a public key on the server.This project will guide you through creating a key pair, copying the public key to the server, and testing the connection.

🎯 Goal: Set up key-based SSH authentication to a remote server so you can log in without a password.

📋 What You'll Learn

Create an SSH key pair with ssh-keygen

Copy the public key to the remote server using ssh-copy-id

Test the SSH connection without a password prompt

💡 Why This Matters

🌍 Real World

Key-based authentication is used daily by system administrators and developers to securely access servers without typing passwords.

💼 Career

Knowing how to set up SSH keys is essential for roles in IT support, DevOps, cloud engineering, and cybersecurity.

1

Generate SSH key pair

Use the command ssh-keygen -t rsa -b 2048 -f ~/.ssh/id_rsa -N "" to create an RSA key pair with no passphrase.

Linux CLI

# Run the ssh-keygen command to create the key pair
# Your code here

Need a hint?

This command creates a 2048-bit RSA key pair without a password. The private key is saved as ~/.ssh/id_rsa and the public key as ~/.ssh/id_rsa.pub.

2

Copy public key to remote server

Use the command ssh-copy-id -i ~/.ssh/id_rsa.pub user@remote_host to copy your public key to the remote server. Replace user and remote_host with the actual username and server address.

Linux CLI

ssh-keygen -t rsa -b 2048 -f ~/.ssh/id_rsa -N ""
# Run ssh-copy-id to copy the public key to the remote server
# Your code here

Need a hint?

This command copies your public key to the remote server's ~/.ssh/authorized_keys file, enabling key-based login.

3

Test SSH connection without password

Use the command ssh user@remote_host to connect to the remote server. You should not be asked for a password.

Linux CLI

ssh-keygen -t rsa -b 2048 -f ~/.ssh/id_rsa -N ""
ssh-copy-id -i ~/.ssh/id_rsa.pub user@remote_host
# Connect to the remote server using ssh
# Your code here

Need a hint?

If set up correctly, this command logs you in without asking for a password.

4

Display success message

After connecting, run echo "Login successful without password" on the remote server to confirm key-based authentication works.

Linux CLI

ssh-keygen -t rsa -b 2048 -f ~/.ssh/id_rsa -N ""
ssh-copy-id -i ~/.ssh/id_rsa.pub user@remote_host
ssh user@remote_host
# Run echo command on remote server
# Your code here

Need a hint?

This message confirms you logged in without typing a password.