PuTTY Complete Guide: SSH, Serial, and Session Management

What is PuTTY?

PuTTY is a free, open-source terminal emulator and SSH client for Windows. It supports SSH, Telnet, Serial (COM port), and raw socket connections. Despite Windows now having a built-in SSH client, PuTTY remains popular for its session management and serial console capabilities.

Downloading and Installing

PuTTY is a portable application—no installation required. Download the appropriate version and run it directly.

Included Tools

• PuTTY.exe – The main terminal client
• PuTTYgen.exe – SSH key generator (creates .ppk key files)
• Pageant.exe – SSH authentication agent (manages keys in memory)
• PSFTP.exe – Command-line SFTP client
• PSCP.exe – Command-line SCP client

Connecting via SSH

SSH is the most common use case for PuTTY—connecting to Linux servers, network devices, and cloud instances.

1. Open PuTTY. In the "Session" category, enter the Host Name (IP address or hostname).
2. Ensure Port is set to 22 and Connection type is SSH.
3. (Optional) Enter a name under "Saved Sessions" and click Save to store for later.
4. Click Open. Accept the host key fingerprint on first connect.
5. Enter your username and password (or use key-based authentication).

Connecting via Serial Console

To connect to network devices via a console cable, use PuTTY's Serial connection type.

1. Connect your console cable to the device and your PC's USB port.
2. In Device Manager, find the assigned COM port (e.g., COM3).
3. In PuTTY, select Connection type: Serial.
4. Enter the COM port in "Serial line" (e.g., COM3).
5. Set "Speed" to 9600 (standard for most devices).
6. Click Open. Press Enter to wake the console.

Standard Serial Settings

In PuTTY, these are set under Connection > Serial.

Using SSH Keys with PuTTY

SSH keys are more secure than passwords. PuTTY uses its own .ppk key format, generated with PuTTYgen.

Generating a Key with PuTTYgen

1. Open PuTTYgen.
2. Select key type EdDSA (Ed25519) for modern security.
3. Click Generate and move your mouse randomly over the window.
4. Enter a Key passphrase (optional but recommended).
5. Click Save private key to save the .ppk file.
6. Copy the text from "Public key for pasting..." and add it to your server's ~/.ssh/authorized_keys.

Using the Key in PuTTY

1. In PuTTY, go to Connection > SSH > Auth > Credentials.
2. Under "Private key file for authentication", click Browse and select your .ppk file.
3. Go back to Session, enter the Host Name, save the session, and connect.

Useful PuTTY Settings

Alternatives to PuTTY

While PuTTY is a classic, there are modern alternatives worth considering:

• 🪟
  Windows Terminal + OpenSSH: Built into Windows 10/11. Just run ssh user@host from PowerShell. No .ppk files—uses standard OpenSSH key format.
• 📱
  SecureCRT: Commercial, feature-rich. Excellent for managing hundreds of sessions with tabs, scripting, and synchronization.
• 🆓
  MobaXterm: Free personal edition. Includes SSH, serial, X11 forwarding, and a built-in file browser.