Secure Shell (SSH) Explained

SSH (Secure Shell) is a widely-used protocol for secure communication over a network.


SSH (Secure Shell) is a widely-used protocol for secure communication over an unsecured network. It provides encrypted communication between two devices, preventing unauthorized access and ensuring data integrity.

Understanding SSH Keys

SSH authentication relies on cryptographic keys rather than passwords. A pair of keys is generated: a private key (kept secret) and a public key (shared with others or stored on servers).

Generating SSH Keys with OpenSSH (Command Line)

OpenSSH is a popular open-source implementation of the SSH protocol. Use the following commands to generate SSH keys:

# Generate SSH key pair
ssh-keygen -t rsa -b 2048 -C ""
# Follow the prompts to save the key in the default location (usually ~/.ssh/id_rsa)

This creates a private key (id_rsa) and a corresponding public key ( Share the public key with services or servers where you want to authenticate.

PuTTY: Generating SSH Keys with PuTTYgen

PuTTY is a widely-used SSH client for Windows. PuTTYgen is a key generator tool that comes with PuTTY.

  1. Open PuTTYgen.
  2. Click "Generate" to create a new key pair.
  3. Save the private key.

Connecting with SSH

OpenSSH (Command Line)

To connect to a server using OpenSSH, use the following command:

ssh username@hostname -p port_number -i path/to/private/key
  • username: Your username on the remote server.
  • hostname: The IP address or domain of the remote server.
  • port_number: The SSH port (default is 22).
  • -i path/to/private/key: Path to your private key.


PuTTY provides a graphical interface for SSH. Enter the hostname or IP address, specify the port, and load your private key under "Connection > SSH > Auth."

SSH Configurations

OpenSSH Config File

Create or edit the ~/.ssh/config file to simplify SSH connections:

# Example SSH Config File
Host myserver
  User username
  Port 2222
  IdentityFile ~/.ssh/id_rsa

Now you can connect with:

ssh myserver

PuTTY Session Saving

Save sessions in PuTTY for quick access. Load a saved session to connect without entering details each time.


SSH, with implementations like OpenSSH and tools like PuTTY, provides a secure way to access and manage remote systems. Understanding key generation, connection commands, and configuration options enhances your ability to use SSH effectively in various scenarios. Whether you're a Linux enthusiast or a Windows user, SSH is a fundamental tool for secure communication and remote management.