Learn how to connect to Linux Virtual Machines on Azure

To connect to a Linux Virtual Machine (VM) in Azure, you primarily use SSH (Secure Shell) to establish a remote terminal session.

Below are the various methods to connect to a Linux VM, with step-by-step instructions for each.

Using SSH (Secure Shell)

Steps

Ensure the VM has a Public IP

1. In the Azure portal, navigate to the Linux VM you want to connect to.

2. Ensure the VM has a Public IP address (check the Overview section of the VM).

3. If it doesn’t have a public IP, you can either assign one or use Azure Bastion or VPN.

Check Network Security Group (NSG) Rules

1. Make sure that the Network Security Group (NSG) attached to your VM or its subnet allows inbound traffic on port 22 (SSH).

2. Go to the Networking tab of the VM in the Azure portal.

3. Verify or create an NSG rule that allows TCP traffic on port 22.

Connect Using SSH

If you’re using Linux or macOS, you can use the built-in Terminal.

On Windows, you can use Windows Subsystem for Linux (WSL), PowerShell, or third-party tools like PuTTY or MobaXterm.

Command

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ssh -i /path/to/your/private-key username@<VM-public-IP>

Replace:

1. /path/to/your/private-key: The path to your private SSH key.

2. username: The username you configured for the Linux VM.

3. <VM-public-IP>: The public IP address of the VM.

Login

If the private key is correctly configured, you should connect to the VM without entering a password (if using key-based authentication).

If you set up password-based authentication, you will be prompted to enter the password.

Note

Ensure that you are using an SSH key pair for more secure access.

If you didn’t set up an SSH key during VM creation, you can also use a username and password to log in (though SSH key-based authentication is preferred for security reasons).

Using Azure Bastion (For Secure Access Without Public IP)

Azure Bastion allows you to securely connect to your Linux VM without exposing it to the public internet (no need for a public IP on the VM).

Steps

Deploy Azure Bastion

In the Azure portal, search for Azure Bastion and create a Bastion host in the same virtual network (VNet) as your Linux VM.

Connect Using Bastion

1. Navigate to the VM in the Azure portal.

2. Click on the Connect button at the top of the VM Overview page.

3. Select the Bastion option.

4. Enter your username and SSH private key or password to authenticate.

Access the VM

After authentication, a browser-based SSH session will open, allowing you to manage the Linux VM securely without needing a public IP.

Benefits

1. No Public IP Exposure: Keeps your Linux VM private and secure by only allowing access through Bastion.

2. Security: Secure, encrypted connection, reducing the attack surface.

Using VPN (Private Network Access)

You can set up a VPN connection to your Azure Virtual Network (VNet), then access your Linux VM using SSH over its private IP address.

Steps

Set Up a VPN Gateway

1. In the Azure portal, create a VPN Gateway for your VNet.

2. Configure a Point-to-Site VPN (for individual clients) or Site-to-Site VPN (for connecting entire networks) to securely connect from your local machine to the Azure VNet.

Connect to the VNet

Once the VPN gateway is set up, connect to your Azure VNet using your VPN client. This creates a secure tunnel between your local machine and Azure.

SSH to the VM Using Private IP

After connecting to the VNet via VPN, use the private IP of the Linux VM to SSH into it:

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ssh -i /path/to/your/private-key username@<VM-private-IP>

The private IP can be found on the Networking tab of the VM in the Azure portal.

Benefits

1. Avoids the need for public IP exposure.

2. Offers a more secure connection by keeping traffic within your private network.

Using Azure Cloud Shell (Browser-Based SSH)

Azure Cloud Shell is a browser-based shell that allows you to interact with your Azure resources, including VMs, without needing any local setup.

Steps

Open Azure Cloud Shell

In the Azure portal, click the Cloud Shell icon at the top-right of the portal.

You can choose either Bash or PowerShell for your environment (Bash is preferred for Linux VMs).

Get the VM's Public IP

Use the following command to retrieve the public IP address of your Linux VM:

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az vm show \
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--name <VM-name> \
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--resource-group <Resource-group-name> \
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--query "publicIps" \
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--output tsv

SSH Using Cloud Shell

Once you have the public IP, use SSH from the Cloud Shell:

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ssh -i /path/to/your/private-key username@<VM-public-IP>

If you are using password authentication, simply enter the password when prompted.

Benefits

1. No local setup required: Everything runs directly in the Azure portal.

2. Convenient for quick access to Azure resources.

Using Serial Console (for Troubleshooting)

The Azure Serial Console provides a way to interact with your Linux VM at a lower level, even if the networking configuration isn’t working (e.g., SSH is misconfigured).

Steps

Access Serial Console

In the Azure portal, navigate to the VM’s Overview page.

Under Support + troubleshooting, click Serial Console.

Login to the Console

A terminal window will appear. Enter the username and password to access your Linux VM.

This method provides direct, low-level access to the VM.

Benefits

1. Useful for recovering from network or SSH failures.

2. Provides out-of-band access to the VM for troubleshooting.

Third-Party SSH Clients (e.g., PuTTY, MobaXterm, Termius)

If you prefer not to use the built-in terminal or Azure Cloud Shell, third-party tools like PuTTY, MobaXterm, or Termius can also be used to SSH into your Linux VM.

Steps

Install Third-Party Client

Download and install your preferred SSH client (e.g., PuTTY, MobaXterm, or Termius).

Configure SSH Client

Launch the client and provide the following details:

1. Host: The public IP address of the Linux VM.

2. Port: 22 (the default SSH port).

3. Authentication: Choose public key or password as per your setup.

Connect

Click Connect, and authenticate using your private key or password.

Using Azure CLI/PowerShell (With Managed Identity)

If you’ve set up Managed Identity on your Linux VM, you can interact with the VM through Azure CLI or PowerShell for automated tasks, but direct SSH will still be needed for interactive access.

Steps

Enable Managed Identity

Ensure the Managed Identity is enabled on your Linux VM.

Use Azure CLI/PowerShell

You can interact with the VM or manage resources using Azure CLI or PowerShell for tasks like retrieving credentials or managing services.

SSH

For actual access, SSH is still required, but Managed Identity helps automate tasks or secure the connection.

Summary

Here are the connections means we learned.

1. SSH (Public IP): The most common method using SSH from your local machine.

2. Azure Bastion: Secure SSH access without a public IP (no exposure to the internet).

3. VPN: Private SSH access via a VPN (no public IP exposure).

4. Azure Cloud Shell: A browser-based shell to SSH into the VM directly.

5. Serial Console: Low-level troubleshooting access if the VM is unresponsive.

6. Third-Party SSH Clients: Tools like PuTTY, MobaXterm, or Termius.

7. Azure CLI/PowerShell with Managed Identity: For automated or scripted access to Azure resources.

By selecting the appropriate method based on your security needs, VM configuration, and access requirements, you can securely and efficiently connect to your Linux VMs on Azure.