How to Setup PuTTY for SSH Key Authentication on Windows 11
SSH key authentication in Windows 11 lets you log into remote servers securely without typing a password, using a matched pair of digital keys instead of standard login credentials.
This setup stops password-guessing attacks by trading typed passwords for cryptographic keys that are nearly impossible to guess. You make these keys using PuTTYgen, a free tool that comes bundled with the PuTTY program.
PuTTYgen creates two files: a public key that you upload to your server and a private key that stays hidden on your PC at all times.
Generate an SSH key pair using PuTTYgen, save both keys, and copy the public key to your server. Then, configure PuTTY by navigating to Connection SSH Auth, browsing to your private key file, and saving the session.
How to download and install PuTTY on 🪟 Windows 11
Connecting securely to other computers starts with downloading and installing PuTTY on Windows 11. Head to the PuTTY download page to grab the 64-bit installer. Save the file to your Downloads folder, open it up, and follow the on-screen prompts to finish the setup.
Select the 64-bit installer and save it to your Downloads folder.
Open your Downloads folder and double-click the installer file to begin.
When you reach the options page, select "Add shortcut to PuTTY on the Desktop" and click Install. Note: This step requires admin privileges.
How to generate a PuTTY SSH key pair
Generating a PuTTY SSH key pair is the crucial first step for setting up secure connections to your server. Use the PuTTYgen tool, which comes with PuTTY, for this process. After opening PuTTYgen, click 'Generate' and move your mouse randomly in the empty space until the progress bar fills up to create your unique key pair.
Find the downloaded file in your Downloads folder and open it.
Click the 'Generate' button. Now, move your mouse cursor randomly around the empty space until the green progress bar fills up.
Once generated, SSH key pairs provide user identification. Adding a descriptive comment to each key pair aids recognition. Save both the public and private key files somewhere safe, such as your user profile directory (C:\Users\your-username):
Your home folder is a good choice, like this: C:\Users\username\.ssh (Replace 'username' with your actual Windows account name).
You might see a warning about not setting a passphrase when saving the Private Key. Click 'Yes' to continue.
Ensure both files are saved in your chosen folder.
How to copy your public key to the server
Copying your public key to the server is the next essential step after generating your SSH key pair, enabling password-free authentication. Access your server, create a `.ssh` directory if it doesn't exist, and then add your public key to the `authorized_keys` file. PuTTYgen provides the public key you need to copy and paste into this file for secure server access.
cd ~/
mkdir .ssh
nano ~/.ssh/authorized_keys
How to turn off password login
Disabling password login on your server boosts security by requiring SSH key authentication. Lock down the server further by editing the main SSH configuration file found at `/etc/ssh/sshd_config`. Change the `PasswordAuthentication` and `ChallengeResponseAuthentication` lines to 'no'. Save the SSH configuration file, then restart the SSH service for these changes to take effect.
On your server, open the configuration file:
sudo nano /etc/ssh/sshd_configFind these lines and make sure they look like this:
PasswordAuthentication no
ChallengeResponseAuthentication no
UsePAM no
Save the file and restart the SSH service:
sudo systemctl restart sshHow to set up PuTTY for your connection
Setting up PuTTY to use your saved SSH key allows you to log in to your server securely without needing a password. In PuTTY, go to the Connection SSH Auth section and browse for your saved private key file. Then, return to the Session tab, enter your username and server IP address, give your session a name, and click 'Save' to store these settings for future access.
Go back to the Session tab. Type your username and server IP address (e.g., username@10.0.2.19). Give it a name and click Save.
This saved session lets you log in securely without a password.
Summary
Setting up PuTTY with SSH keys makes your server connections more secure and faster. By following these steps, you have installed the necessary software, created a secure key pair, updated your server settings, and configured PuTTY for password-free access.
How do I authenticate a private key in PuTTY?
To use your private key in PuTTY, open PuTTY, go to Connection SSH Auth. Click 'Browse' next to 'Private key file for authentication' and select your saved private key file. Then, go to Session and save your settings.
How to do SSH key authentication?
SSH key authentication uses a public and a private key. The public key goes on the server, and your SSH client (like PuTTY) uses the private key to prove your identity instead of a password.
How to add PuTTY public key to Authorized_keys?
Copy your public key from PuTTYgen. Log into your server using PuTTY. Open the 'authorized_keys' file in a text editor. Paste the public key into this file and save it. This lets your private key connect without a password.
What is a PuTTY authentication agent?
A PuTTY authentication agent, like Pageant, holds your private keys securely in memory. This means you don't have to enter your key's passphrase every time you connect to a server, making logins quicker.
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About the Author
Richard
Tech Writer, IT Professional
Richard, a writer for Geek Rewind, is a tech enthusiast who loves breaking down complex IT topics into simple, easy-to-understand ideas. With years of hands-on experience in system administration and enterprise IT operations, he’s developed a knack for offering practical tips and solutions. Richard aims to make technology more accessible and actionable. He's deeply committed to the Geek Rewind community, always ready to answer questions and engage in discussions.
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