🚀 **Mastering PuTTY for SSH Key Authentication: A Complete Guide for IT Pros**

PuTTY is a versatile Windows tool for secure remote server access. By using SSH key authentication, you replace passwords with cryptographic keys, boosting both security and convenience. This guide walks you through key generation, configuration, and connection, making your remote sessions seamless.

➤ Installing PuTTY and PuTTYgen

1. Download PuTTY from the official site and run the installer.
2. Installation is straightforward: Next → Next → Install.
3. PuTTYgen, included in the installation, is used to generate and manage SSH keys.

➤ Generating SSH Keys

1. Launch PuTTYgen (C:\Program Files\PuTTY\puttygen.exe).
2. Select a key type (RSA or Ed25519 recommended) and click Generate.
3. Move your mouse randomly to create entropy for the key.
4. Save the private key locally using Save private key.
5. Copy the public key from the field Public key for pasting into OpenSSH authorized_keys file.

💡 Tip: Keep your private key secure. Do not share it.

➤ Configuring PuTTY for SSH Key Authentication

1. Open PuTTY and enter your server’s hostname or IP address.
2. In the left panel: Connection → SSH → Auth → Browse → select your saved private key (.ppk).
3. (Optional) Go to Connection → Data and set a default username for auto-login.
4. Return to Session, give your connection a name, and click Save.

➤ Connecting to the Server

1. On your server, add the public key to ~/.ssh/authorized_keys.
2. Ensure proper permissions: chmod 600 ~/.ssh/authorized_keys.
3. Back in PuTTY, click Open to initiate the session.
4. Enter your username if not pre-set; PuTTY will authenticate via the key.
5. If successful, you’ll see a confirmation like: “Authenticating with public key”.

➤ Tips and Best Practices

• Always backup your private key in a secure location.
• Keep PuTTY updated to the latest version for security improvements.
• If connection fails, verify key paths, permissions, and server SSH settings.
• Use session bookmarks for frequently accessed servers.

➤ Advantages of SSH Key Authentication

• 🔒 Stronger security compared to passwords
• ⚡ Faster login without repeated password entry
• 🛠️ Automation-friendly for scripts and server management
• 🌐 Centralized control for multiple servers

📈 Summary

Using SSH key authentication with PuTTY enhances both the security and efficiency of remote server management. Once set up, you can connect to multiple servers quickly and safely, making it ideal for IT specialists and SMBs managing remote infrastructure.

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