How to Set Up SSH Key Authentication on Ubuntu 24.04

🔐 How to Set Up SSH Key Authentication on Ubuntu 24.04

If you're tired of typing your password every time you connect to your server — or you're aiming for stronger security — using SSH keys is the way to go. This guide will walk you through generating an SSH key and setting it up on an Ubuntu 24.04 server.

✅ Step 1: Generate SSH Key Pair (on your local machine)

Open your terminal and run:

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

 -t rsa: specifies RSA encryption.
 
 -b 4096: sets the key length to 4096 bits.
 
 -C: adds a comment (usually your email).

When prompted:

Press Enter to accept the default location (~/.ssh/id_rsa).

Enter a passphrase for extra protection (optional).

This will generate two files:

~/.ssh/id_rsa → your private key (keep it safe and never share it).
 
~/.ssh/id_rsa.pub → your public key (you'll upload this to your server).

✅ Step 2: Copy the Public Key to Your Ubuntu Server

Connect to your server (temporarily using a password):

ssh username@your-server-ip Now, on the server:

Create the .ssh directory (if it doesn't exist):

mkdir -p ~/.ssh
chmod 700 ~/.ssh

Add your public key to the authorized_keys file:

You can paste it manually:

nano ~/.ssh/authorized_keys

Paste the contents of id_rsa.pub, save and exit (Ctrl + O, Enter, then Ctrl + X).

Then set proper permissions:

chmod 600 ~/.ssh/authorized_keys

✅ Step 3: (Optional) Disable Password Authentication

To enhance security, you can disable password logins:

sudo nano /etc/ssh/sshd_config

Ensure these lines are uncommented:

PubkeyAuthentication yes
PasswordAuthentication no

Then restart the SSH service:

sudo systemctl restart ssh

✅ Step 4: Log In with SSH Key

From your local machine, connect again:

ssh username@your-server-ip

You should be logged in without being asked for a password.

🎉 Done! You’ve successfully set up SSH key authentication on Ubuntu 24.04. It’s faster, safer, and one step closer to being a true Linux pro 💻🔐