Create And Generating Ssh Keys
- Create And Generating Ssh Keys On Linux
- How To Create A New Ssh Key
- Generating An Ssh Key Pair
- Generating A New Ssh Key
- Create And Generating Ssh Keys On Windows
With a secure shell (SSH) key pair, you can create a Linux virtual machine on Azure that defaults to using SSH keys for authentication, eliminating the need for passwords to sign in. VMs created with the Azure portal, Azure CLI, Resource Manager templates, or other tools can include your SSH public key as part of the deployment, which sets up SSH key authentication for SSH connections.
This article provides detailed background and steps to create and manage an SSH RSA public-private key file pair for SSH client connections. If you want quick commands, see How to create an SSH public-private key pair for Linux VMs in Azure.
For additional ways to generate and use SSH keys on a Windows computer, see How to use SSH keys with Windows on Azure.
- Aug 19, 2019 Using SSH keys for authentication is highly recommended, as a safer alternative to passwords. This tutorial will guide you through the steps on how to generate and set up SSH keys on CentOS 7. We also cover connecting to a remote server using the keys.
- Generating a Secure Shell (SSH) Public/Private Key Pair Several tools exist to generate SSH public/private key pairs. The following sections show how to generate an SSH key pair on UNIX, UNIX-like and Windows platforms.
Overview of SSH and keys
SSH is an encrypted connection protocol that allows secure sign-ins over unsecured connections. SSH is the default connection protocol for Linux VMs hosted in Azure. Although SSH itself provides an encrypted connection, using passwords with SSH connections still leaves the VM vulnerable to brute-force attacks or guessing of passwords. A more secure and preferred method of connecting to a VM using SSH is by using a public-private key pair, also known as SSH keys.
Creating an SSH key on Windows 1. Check for existing SSH keys. You should check for existing SSH keys on your local computer. You can use an existing SSH key with Bitbucket Server if you want, in which case you can go straight to either SSH user keys for personal use or SSH access keys for system use. Open a command prompt, and run. Mar 31, 2020 By creating and managing SSH keys, you can let users access a Linux instance through third-party tools. An SSH key consists of the following files: A public SSH key file that is applied to.
The public key is placed on your Linux VM, or any other service that you wish to use with public-key cryptography.
The private key remains on your local system. Protect this private key. Do not share it.
When you use an SSH client to connect to your Linux VM (which has the public key), the remote VM tests the client to make sure it possesses the private key. If the client has the private key, it's granted access to the VM. Mac mail for windows download. /java-server-generate-key-pair.html.
Depending on your organization's security policies, you can reuse a single public-private key pair to access multiple Azure VMs and services. You do not need a separate pair of keys for each VM or service you wish to access.
Your public key can be shared with anyone, but only you (or your local security infrastructure) should possess your private key.
Private key passphrase
The SSH private key should have a very secure passphrase to safeguard it. This passphrase is just to access the private SSH key file and is not the user account password. When you add a passphrase to your SSH key, it encrypts the private key using 128-bit AES, so that the private key is useless without the passphrase to decrypt it. If an attacker stole your private key and that key did not have a passphrase, they would be able to use that private key to sign in to any servers that have the corresponding public key. If a private key is protected by a passphrase, it cannot be used by that attacker, providing an additional layer of security for your infrastructure on Azure.
Supported SSH key formats
Azure currently supports SSH protocol 2 (SSH-2) RSA public-private key pairs with a minimum length of 2048 bits. Other key formats such as ED25519 and ECDSA are not supported.
SSH keys use and benefits
When you create an Azure VM by specifying the public key, Azure copies the public key (in the .pub
format) to the ~/.ssh/authorized_keys
folder on the VM. SSH keys in ~/.ssh/authorized_keys
are used to challenge the client to match the corresponding private key on an SSH connection. In an Azure Linux VM that uses SSH keys for authentication, Azure configures the SSHD server to not allow password sign-in, only SSH keys. Therefore, by creating an Azure Linux VM with SSH keys, you can help secure the VM deployment and save yourself the typical post-deployment configuration step of disabling passwords in the sshd_config
file.
If you do not wish to use SSH keys, you can set up your Linux VM to use password authentication. If your VM is not exposed to the Internet, using passwords may be sufficient. However, you still need to manage your passwords for each Linux VM and maintain healthy password policies and practices, such as minimum password length and regular updates. Using SSH keys reduces the complexity of managing individual credentials across multiple VMs.
Generate keys with ssh-keygen
To create the keys, a preferred command is ssh-keygen
, which is available with OpenSSH utilities in the Azure Cloud Shell, a macOS or Linux host, the Windows Subsystem for Linux, and other tools. ssh-keygen
asks a series of questions and then writes a private key and a matching public key.
SSH keys are by default kept in the ~/.ssh
directory. If you do not have a ~/.ssh
directory, the ssh-keygen
command creates it for you with the correct permissions.
Basic example
The following ssh-keygen
command generates 2048-bit SSH RSA public and private key files by default in the ~/.ssh
directory. If an SSH key pair exists in the current location, those files are overwritten.
Detailed example
The following example shows additional command options to create an SSH RSA key pair. If an SSH key pair exists in the current location, those files are overwritten.
Command explained
ssh-keygen
= the program used to create the keys
-m PEM
= format the key as PEM
-t rsa
= type of key to create, in this case in the RSA format
-b 4096
= the number of bits in the key, in this case 4096
-C 'azureuser@myserver'
= a comment appended to the end of the public key file to easily identify it. Normally an email address is used as the comment, but use whatever works best for your infrastructure.
-f ~/.ssh/mykeys/myprivatekey
= the filename of the private key file, if you choose not to use the default name. A corresponding public key file appended with .pub
is generated in the same directory. The directory must exist.
-N mypassphrase
= an additional passphrase used to access the private key file.
Example of ssh-keygen
Saved key files
Enter file in which to save the key (/home/azureuser/.ssh/id_rsa): ~/.ssh/id_rsa
The key pair name for this article. Having a key pair named id_rsa
is the default; some tools might expect the id_rsa
private key file name, so having one is a good idea. The directory ~/.ssh/
is the default location for SSH key pairs and the SSH config file. If not specified with a full path, ssh-keygen
creates the keys in the current working directory, not the default ~/.ssh
.
List of the ~/.ssh
directory
Key passphrase
Enter passphrase (empty for no passphrase):
It is strongly recommended to add a passphrase to your private key. Without a passphrase to protect the key file, anyone with the file can use it to sign in to any server that has the corresponding public key. Adding a passphrase offers more protection in case someone is able to gain access to your private key file, giving you time to change the keys.
Generate keys automatically during deployment
If you use the Azure CLI to create your VM, you can optionally generate SSH public and private key files by running the az vm create command with the --generate-ssh-keys
option. The keys are stored in the ~/.ssh directory. Note that this command option does not overwrite keys if they already exist in that location.
Provide SSH public key when deploying a VM
To create a Linux VM that uses SSH keys for authentication, provide your SSH public key when creating the VM using the Azure portal, CLI, Resource Manager templates, or other methods. When using the portal, you enter the public key itself. If you use the Azure CLI to create your VM with an existing public key, specify the value or location of this public key by running the az vm create command with the --ssh-key-value
option.
If you're not familiar with the format of an SSH public key, you can see your public key by running cat
as follows, replacing ~/.ssh/id_rsa.pub
with your own public key file location:
Output is similar to the following (here redacted):
If you copy and paste the contents of the public key file into the Azure portal or a Resource Manager template, make sure you don't copy any additional whitespace or introduce additional line breaks. For example, if you use macOS, you can pipe the public key file (by default, ~/.ssh/id_rsa.pub
) to pbcopy to copy the contents (there are other Linux programs that do the same thing, such as xclip
).
If you prefer to use a public key that is in a multiline format, you can generate an RFC4716 formatted key in a pem container from the public key you previously created.
To create a RFC4716 formatted key from an existing SSH public key:
SSH to your VM with an SSH client
With the public key deployed on your Azure VM, and the private key on your local system, SSH to your VM using the IP address or DNS name of your VM. Replace azureuser and myvm.westus.cloudapp.azure.com in the following command with the administrator user name and the fully qualified domain name (or IP address):
If you provided a passphrase when you created your key pair, enter the passphrase when prompted during the sign-in process. (The server is added to your ~/.ssh/known_hosts
folder, and you won't be asked to connect again until the public key on your Azure VM changes or the server name is removed from ~/.ssh/known_hosts
.)
If the VM is using the just-in-time access policy, you need to request access before you can connect to the VM. For more information about the just-in-time policy, see Manage virtual machine access using the just in time policy.
Use ssh-agent to store your private key passphrase
To avoid typing your private key file passphrase with every SSH sign-in, you can use ssh-agent
to cache your private key file passphrase. If you are using a Mac, the macOS Keychain securely stores the private key passphrase when you invoke ssh-agent
.
Verify and use ssh-agent
and ssh-add
to inform the SSH system about the key files so that you do not need to use the passphrase interactively.
Now add the private key to ssh-agent
using the command ssh-add
.
The private key passphrase is now stored in ssh-agent
.
Use ssh-copy-id to copy the key to an existing VM
If you have already created a VM, you can install the new SSH public key to your Linux VM with a command similar to the following:
Create and configure an SSH config file
You can create and configure an SSH config file (~/.ssh/config
) to speed up log-ins and to optimize your SSH client behavior.
The following example shows a simple configuration that you can use to quickly sign in as a user to a specific VM using the default SSH private key.
Create the file
Edit the file to add the new SSH configuration
Example configuration
Create And Generating Ssh Keys On Linux
Add configuration settings appropriate for your host VM.
You can add configurations for additional hosts to enable each to use its own dedicated key pair. See SSH config file for more advanced configuration options.
Now that you have an SSH key pair and a configured SSH config file, you are able to sign in to your Linux VM quickly and securely. When you run the following command, SSH locates and loads any settings from the Host myvm
block in the SSH config file.
The first time you sign in to a server using an SSH key, the command prompts you for the passphrase for that key file.
Next steps
Next up is to create Azure Linux VMs using the new SSH public key. Azure VMs that are created with an SSH public key as the sign-in are better secured than VMs created with the default sign-in method, passwords.
On Windows, you can create SSH keys in many ways. This document explains how to use two SSH applications, PuTTY and Git Bash.
Joyent recommends RSA keys because the node-manta CLI programs work with RSA keys both locally and with the ssh agent. DSA keys will work only if the private key is on the same system as the CLI, and not password-protected.
PuTTY
PuTTY is an SSH client for Windows. You can use PuTTY to generate SSH keys. PuTTY is a free open-source terminal emulator that functions much like the Terminal application in macOS in a Windows environment. This section shows you how to manually generate and upload an SSH key when working with PuTTY in the Windows environment.
About PuTTY
PuTTY is an SSH client for Windows that you will use to generate your SSH keys. You can download PuTTY from www.chiark.greenend.org.uk.
When you install the PuTTY client, you also install the PuTTYgen utility. PuTTYgen is what you will use to generate your SSH key for a Windows VM.
This page gives you basic information about using PuTTY and PuTTYgen to log in to your provisioned machine. For more information on PuTTY, see the PuTTY documentation |
---|
Generating an SSH key
To generate an SSH key with PuTTYgen, follow these steps:
- Open the PuTTYgen program.
- For Type of key to generate, select SSH-2 RSA.
- Click the Generate button.
- Move your mouse in the area below the progress bar. When the progress bar is full, PuTTYgen generates your key pair.
- Type a passphrase in the Key passphrase field. Type the same passphrase in the Confirm passphrase field. You can use a key without a passphrase, but this is not recommended.
- Click the Save private key button to save the private key. You must save the private key. You will need it to connect to your machine.
- Right-click in the text field labeled Public key for pasting into OpenSSH authorized_keys file and choose Select All.
- Right-click again in the same text field and choose Copy.
Importing your SSH key
Now you must import the copied SSH key to the portal.
- After you copy the SSH key to the clipboard, return to your account page.
- Choose to Import Public Key and paste your SSH key into the Public Key field.
- In the Key Name field, provide a name for the key. Note: although providing a key name is optional, it is a best practice for ease of managing multiple SSH keys.
- Add the key. It will now appear in your table of keys under SSH.
PuTTY and OpenSSH use different formats of public SSH keys. If the text you pasted in the SSH Key starts with —— BEGIN SSH2 PUBLIC KEY
, it is in the wrong format. Be sure to follow the instructions carefully. Your key should start with ssh-rsa AAAA…
.
How To Create A New Ssh Key
Once you upload your SSH key to the portal, you can connect to your virtual machine from Windows through a PuTTY session.
Git Bash
The Git installation package comes with SSH. Using Git Bash, which is the Git command line tool, you can generate SSH key pairs. Git Bash has an SSH client that enables you to connect to and interact with Triton containers on Windows.
To install Git:
- (Download and initiate the Git installer](https://git-scm.com/download/win).
- When prompted, accept the default components by clicking Next.
- Choose the default text editor. If you have Notepad++ installed, select Notepad++ and click Next.
- Select to Use Git from the Windows Command Prompt and click Next.
- Select to Use OpenSSL library and click Next.
- Select to Checkout Windows-style, commit Unix-style line endings and click Next.
- Select to Use MinTTY (The default terminal of mYSYS2) and click Next.
- Accept the default extra option configuration by clicking Install.
When the installation completes, you may need to restart Windows.
Launching GitBash
To open Git Bash, we recommend launching the application from the Windows command prompt:
- In Windows, press Start+R to launch the Run dialog.
- Type
C:Program FilesGitbinbash.exe
and press Enter.
Generating SSH keys
First, create the SSH directory and then generate the SSH key pair.
One assumption is that the Windows profile you are using is set up with administrative privileges. Given this, you will be creating the SSH directory at the root of your profile, for example:
Generating An Ssh Key Pair
- At the Git Bash command line, change into your root directory and type.
Change into the .ssh directory
C:Usersjoetest.ssh
- To create the keys, type:
- When prompted for a password, type apassword to complete the process. When finished, the output looks similar to:
Uploading an SSH key
To upload the public SSH key to your Triton account:
- Open Triton Service portal, select Account to open the Account Summary page.
- From the SSH section, select Import Public Key.
- Enter a Key Name. Although naming a key is optional, labels are a best practice for managing multiple SSH keys.
- Add your public SSH key.
Generating A New Ssh Key
When Triton finishes the adding or uploading process, the public SSH key appears in the list of SSH keys.
What are my next steps?
Create And Generating Ssh Keys On Windows
- Adding SSH keys to agent.
- Set up the Triton CLI and CloudAPI on Windows.
- Set up the Triton CLI and CloudAPI.
- Create an instance in the Triton Service Portal.
- Set up the
triton-docker
command line tool. - Visit PuTTYgen to learn more about the PuTTYgen and to seethe complete installation and usage guide.