Different Ways to SSH into a Linux VM on Azure

Introduction

Connecting to a Linux Virtual Machine (VM) on Azure via SSH is essential for managing and interacting with your VM. Azure provides multiple ways to achieve this, catering to different scenarios and security requirements. This guide outlines all the popular methods, including Azure-specific options and generic SSH methods.

1. SSH with Public Key Authentication

This is the most common and secure method to SSH into a VM.

Steps:

• Generate an SSH Key Pair: Use ssh-keygen on your local system to create a public and private key.

• Add the Public Key to Your VM: During VM creation, upload your public key so it’s added to the VM’s ~/.ssh/authorized_keys file.

• Connect to the VM: Use the private key to connect:

  ssh -i /path/to/private_key username@vm_ip_address

When to Use: When security is a priority and you want passwordless login.

2. SSH with Password Authentication

Steps:

• Ensure Password Authentication is Enabled: Configure your VM to allow password-based SSH.

• Connect: Use an SSH client and your username/password combination:

  ssh username@vm_ip_address

When to Use: When you haven’t set up SSH keys, but note that this is less secure.

3. Azure Bastion Service

Azure Bastion allows you to securely SSH into your VM without exposing it to the public internet.

Steps:

• Deploy Azure Bastion: Set up Bastion in the same virtual network as your VM.

• Connect via Azure Portal: Navigate to your VM, select “Connect” > “Bastion”, and start the session.

When to Use: When you need a secure, browser-based SSH session without configuring SSH keys or exposing your VM.

4. Azure Cloud Shell

Azure Cloud Shell is an in-browser terminal that comes with Azure tools pre-installed.

Steps:

• Launch Cloud Shell: Open the Azure portal and start Cloud Shell.

• Connect to the VM: Use the SSH command:

  ssh username@vm_ip_address

When to Use: When you want to quickly access your VM from any browser without local SSH client setup.

5. SSH via Azure CLI

You can SSH into a VM directly from the Azure Command-Line Interface (CLI).

Steps:

• Install Azure CLI: Ensure Azure CLI is installed on your system.

• Use the az ssh Command:

  az ssh vm --name VMName --resource-group ResourceGroupName

When to Use: When you already use Azure CLI for managing Azure resources.

6. SSH with Azure Active Directory (AAD) Authentication

Authenticate using Azure AD credentials for centralized identity management.

Steps:

• Enable AAD Login: Configure your VM to allow Azure AD login.

• Assign Roles: Assign the required Azure roles like "Virtual Machine User Login."

• Connect: Use an SSH client that supports Azure AD authentication.

When to Use: When you want to centralize identity and access management for your VMs.

7. PuTTY (Windows-Specific Option)

PuTTY is a popular SSH client for Windows users.

Steps:

• Download PuTTY: Get it from the official site.

• Convert Keys (if needed): Use PuTTYgen to convert OpenSSH keys to .ppk format.

• Configure and Connect:

  • Enter your VM’s IP in the “Host Name” field.

  • Go to “Connection > SSH > Auth” and load your .ppk key.

  • Click “Open” to connect.

When to Use: When you’re on Windows and need a graphical SSH client with advanced features like saved sessions or tunneling.

Choosing the Right Option

Conclusion

By understanding these options, we can choose the most appropriate method for our use case and ensure secure and reliable access to our Azure Linux VM. Let us know in the comments which method you prefer or if you have any tips to share!