2.1K

SSH (Secure Shell) is a network protocol that allows secure remote access to a Linux server. Normally, users authenticate using a password when connecting via SSH. However, passwordless authentication using SSH keys provides improved security and faster login access.

This guide explains how to configure passwordless SSH login using PuTTY and PuTTYgen.

What Is Passwordless SSH Login?

Passwordless SSH authentication uses a public and private key pair instead of passwords:

• Private key – Stored securely on your local system
• Public key – Added to the remote Linux server

Once configured, you can log in securely without entering a password.

Step 1: Download Required Tools

Download the following utilities:

• PuTTY – SSH and Telnet client
• PuTTYgen – SSH key generation tool

Download the latest versions of putty.exe and puttygen.exe and launch PuTTYgen.

Step 2: Generate SSH Keys

1. Open PuTTYgen
2. Keep the default option SSH-2 RSA
3. Click Generate
4. Move your mouse randomly inside the window to create entropy
5. Click Save private key and store it securely
6. Copy the text shown under Public key

Step 3: Upload Public Key to Linux Server

1. Open PuTTY
2. Connect to the Linux server using username and password
3. Navigate to the home directory

Create the SSH directory if it does not exist:

mkdir -p ~/.ssh

Create the authorized keys file:

vi ~/.ssh/authorized_keys

Paste the copied public key into this file.

Step 4: Set Correct Permissions

Run the following command:

chmod 600 ~/.ssh/authorized_keys

This ensures proper security permissions for SSH authentication.

Step 5: Configure PuTTY for Key Authentication

1. Open PuTTY
2. Enter the server IP address
3. Go to Connection → Data
4. Enter the Auto-login username
5. Navigate to Connection → SSH → Auth
6. Browse and select the saved private key
7. Click Open

Step 6: Login Without Password

After completing the configuration, PuTTY will authenticate using the SSH key, allowing direct login without entering a password.

Benefits of Passwordless SSH Login

• Faster server access
• Stronger authentication security
• Protection against brute-force attacks
• Convenient automated logins

Conclusion

Setting up passwordless SSH login using PuTTY improves both security and usability. By using SSH key authentication, administrators can securely access Linux servers without relying on passwords.

If you require help, contact SupportPRO Server Admin