You can create a Linux VM in Azure with password or SSH keys. In this blog, we will see how to create a Linux VM using SSH key pair and connect from Azure CLI and Windows Powershell.
For creating Azure VM you need to have a valid Azure account. If you do not have it, you can create using Azure Portal for free.
SSH Keypair includes two keys one is public and the other one is private. The public key is kept on the server, and the server can be connected only to clients having corresponding private keys. Public keys are added to the authorized_keys file.
This is a tool to create new authentication key pair, this key pair can be used for automating logins, single sign-on, and for authenticating host machines. You can use the ssh-keygen command on Azure cloud shell, macOS, Linux, or Windows 10.
Start Azure Cloud shell from Azure Portal and execute the below code to create SSH Keypair.
ssh-keygen \ -m PEM \ -t rsa \ -b 4096 \ -C "azureuser@testserver" \ -f ~/.ssh/officekey
This generates an SSH Key pair and store in ~/.ssh directory.
Azure CLI will ask Enter Passphrase. You can secure SSH Keys by using Passphrase, you will have to enter this Passphrase every time while connecting to VM. You can use an SSH agent to configure authentication so that you do not need to re-enter the password after the first successful VM connection.
This command will show output like this.
Generating public/private rsa key pair. Created directory '/home/user/.ssh'. Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/user/.ssh/officekey. Your public key has been saved in /home/user/.ssh/officekey.pub. The key fingerprint is: SHA256:HCm+GuettwrkeU05i13fUvQfsVtBjjG7Ks7JP21XR8w azureuser@testserver The key's randomart image is: +---[RSA 4096]----+ | o . | | . B | | . o o.* | | . o o ...E| | . . S . ..+o| | o . * + ..o B| | = = +. .+ ..+| | B .= o. + . | | . ++o*..o . | +----[SHA256]-----+
You can list all SSH Keys by using the following command.
ls -al ~/.ssh
You can create an Azure Linux Virtual Machine using Azure CLI, Azure Portal, Powershell, or ARM templates. For this tutorial, we will use Azure CLI.
Execute the following command using Azure CLI to create Linux VM with the officekey SSH Key created in the previous step.
az vm create \ --resource-group cloud-shell-storage-centralindia \ --name testserver \ --image UbuntuLTS\ --admin-username azureuser \ --ssh-key-value ~/.ssh/officekey.pub
az vm create \ --resource-group cloud-shell-storage-centralindia \ --name testserver \ --image UbuntuLTS\ --admin-username azureuser \ --generate-ssh-keys
Execution takes 1-2 minutes and shows a JSON with newly created Linux VM details as output.
Your VM is ready to connect. Note the public IP address of VM listed in the JSON file. Or you can search Virtual Machine in Azure Portal -> Click on testserver, this displays details of testserver Linux VM.
The VM I created has the public IP address - 184.108.40.206 and we have used the admin user as azureuser while creating VM. So connect this Linux VM using Azure CLI you can use the following command.
ssh -i ~/.ssh/officekey firstname.lastname@example.org
Following are details of the SSH command
The Linux VM created in previous step can be connect from Windows Powershell commands. In this step you will create a SSH key using Powershell.
Start Powershell from your machine and execute the following command.
ssh-keygen -m PEM -t rsa -b 4096 -f "L:\sshkeys\homeuserkeys"
This creates a SSH key pair and stores it to the location L:\sshkeys. If you do not specify location, SSH key will be stored at default location - C:\Users\<user name>\.ssh
You can verify the SSH key pair, private key in homeuserkeys file and public key in homeuserkeys.pub.
The private key will be like this.
----BEGIN RSA PRIVATE KEY----- MIIJKQIBAAKCAgEAsnnR3CRGGb6hRLZXMZXMKdFcc3eNg/XE9ZHNDgyiBSP4T2Tw /RKac6g2qoM3bZfiuq9t44IPzIi2nIN9qVIAywS24Z+w+TSP4KcVi/uiYNiSVJlQ qpgvM1kVPcmt0BtvHMjvWp6QRFeo5ARi0zhtcoxc/yLWI4oLEJVnXQlU629OsvgL 9CEQHto01GuZ+dBlEB6rTuvZ0PfSJCWGnc0X5X0JzpNwyZLaRqzQxadLsmlwVvxQ JiBMK/aKUX4cBFi4BjD1OVq1PgAOLs75S9bpe2W2p+KcQwizL6B895L7+K7BDjGJ 3O5E2q4yvU1uh/5xdgkn6pG1cFvdTdufTSXMabbjMuXwP0T0xRQ6b9jIPhSQwraj 0yuyD/xTxJiBHyyPMrtyARvFi0HsVSpBZodIowlxbaBt6GNH613Vs+llu8qjZi+s --more encrypted text -----END RSA PRIVATE KEY-----
SSH key generated through Windows Powershell can be used to connect Azure Linux VM. For this, you will have to update VM's SSH details with an SSH public key.
From Azure Portal search for the VM you created in previous steps. Virtual Machines -> testserver.
Under Support + Troubleshooting Click on Reset Password.
On the right side of the window, Select Reset SSH Public Key as mode, then for Username enter homeuser.
Copy all the content from homeuserkeys.pub generated on your windows machine, and paste to VM's SSH Public Key as shown in the following picture.
As SSH Public key content generated on Windows machine is updated to Azure Linux VM SSH and private key resides in local windows machine. You should be able to connect this VM using Windows Powershell.
Open the Powershell as Administrator and execute below command.
ssh -i L:\sshkeys\homeuserkeys email@example.com -v
Summary: Now you should be able to connect the same Azure Linux VM from Azure CLI as well as Windows Powershell.