Before adding a new SSH key to the ssh-agent, you should have checked for existing SSH keys and generated a new SSH key. Ensure ssh-agent is enabled: start the ssh-agent in the background. Eval '$(ssh-agent -s)' Agent pid 59566. Add your SSH key to the ssh-agent. If you used an existing SSH key rather than generating a new SSH key, you'll need. Furthermore SSH key authentication can be more convenient than the more traditional password authentication. When used with a program known as an SSH agent, SSH keys can allow you to connect to a server, or multiple servers, without having to remember or enter your password for each system.
-->Most authentication in Windows environments is done with a username-password pair.This works well for systems that share a common domain.When working across domains, such as between on-premise and cloud-hosted systems, it becomes vulnerable to brute force intrusions.
By comparison, Linux environments commonly use public-key/private-key pairs to drive authentication which doesn't require the use of guessable passwords.OpenSSH includes tools to help support this, specifically:
- ssh-keygen for generating secure keys
- ssh-agent and ssh-add for securely storing private keys
- scp and sftp to securely copy public key files during initial use of a server
This document provides an overview of how to use these tools on Windows to begin using key authentication with SSH.If you are unfamiliar with SSH key management, we strongly recommend you review NIST document IR 7966 titled 'Security of Interactive and Automated Access Management Using Secure Shell (SSH).'
About key pairs
Key pairs refer to the public and private key files that are used by certain authentication protocols.
SSH public-key authentication uses asymmetric cryptographic algorithms to generate two key files – one 'private' and the other 'public'. The private key files are the equivalent of a password, and should stay protected under all circumstances. If someone acquires your private key, they can log in as you to any SSH server you have access to. The public key is what is placed on the SSH server, and may be shared without compromising the private key.
Apple mac update 2020. When using key authentication with an SSH server, the SSH server and client compare the public keys for username provided against the private key. If the server-side public key cannot be validated against the client-side private key, authentication fails.
Multi-factor authentication may be implemented with key pairs by requiring that a passphrase be supplied when the key pair is generated (see key generation below).During authentication the user is prompted for the passphrase, which is used along with the presence of the private key on the SSH client to authenticate the user.
Host key generation
Public keys have specific ACL requirements that, on Windows, equate to only allowing access to administrators and System.To make this easier,
- The OpenSSHUtils PowerShell module has been created to set the key ACLs properly, and should be installed on the server
- On first use of sshd, the key pair for the host will be automatically generated. If ssh-agent is running, the keys will be automatically added to the local store.
Macbook pro late 2011 latest update. To make key authentication easy with an SSH server, run the following commands from an elevated PowerShell prompt:
Since there is no user associated with the sshd service, the host keys are stored under ProgramDatassh.
User key generation
To use key-based authentication, you first need to generate some public/private key pairs for your client.From PowerShell or cmd, use ssh-keygen to generate some key files.
This should display something like the following (where 'username' is replaced by your user name)
You can hit Enter to accept the default, or specify a path where you'd like your keys to be generated.At this point, you'll be prompted to use a passphrase to encrypt your private key files.The passphrase works with the key file to provide 2-factor authentication.For this example, we are leaving the passphrase empty.
Now you have a public/private ED25519 key pair(the .pub files are public keys and the rest are private keys):
Remember that private key files are the equivalent of a password should be protected the same way you protect your password.To help with that, use ssh-agent to securely store the private keys within a Windows security context, associated with your Windows login.To do that, start the ssh-agent service as Administrator and use ssh-add to store the private key.
After completing these steps, whenever a private key is needed for authentication from this client, ssh-agent will automatically retrieve the local private key and pass it to your SSH client.
Note
It is strongly recommended that you back up your private key to a secure location,then delete it from the local system, after adding it to ssh-agent.The private key cannot be retrieved from the agent.If you lose access to the private key, you would have to create a new key pairand update the public key on all systems you interact with.
Deploying the public key
To use the user key that was created above, the public key needs to be placed on the server into a text file called authorized_keys under usersusername.ssh.The OpenSSH tools include scp, which is a secure file-transfer utility, to help with this.
Ssh Key Github
To move the contents of your public key (~.sshid_ed25519.pub) into a text file called authorized_keys in ~.ssh on your server/host.
This example uses the Repair-AuthorizedKeyPermissions function in the OpenSSHUtils module which was previously installed on the host in the instructions above.
These steps complete the configuration required to use key-based authentication with SSH on Windows.After this, the user can connect to the sshd host from any client that has the private key.
Enable the SSH server in Windows
You need to add the optional feature ‘OpenSSH Server’ in Windows 10 first by going to Settings -> search for Add an optional feature -> search again for OpenSSH Client and choose to install.
Configure SSH service to automatically start
By default Windows won’t start the ssh-agent. You can tell Windows to start the service automatically in the future by running the following command in PowerShell (as Administrator).
But right now, manually start the service by running
Generate the key
Open PowerShell and follow these commands to generate SSH key on your machine.
Keep the default location for where to save the key. This should be C:Users<username>/.ssh/id_rsa.
Generate a complex password and store in safe place, ideally a password manager.Enter this password when prompted. When complete you’ll be shown the key fingerprint and the key's randomart image.
Add key to the SSH Agent
We need to add the key to our ssh-agent so we don’t have to type the key each time we use it.
The agent will recognise that a new key is present and will ask for the passphrase.
Once entered you’ll see the confirmation message Identity added.
I still needed to manually add the key to the ssh-agent. To do so navigate to the .ssh folder where we stored our keys earlier C:Users<username>/.ssh/ and run the following with the correct key name.
This will prompt you to enter the passphrase in and once again you should see the Identity added confirmation.
Access your public key
Now we have our key we can add it to systems such as GitHub or Bitbucket. To do so follow the instructions for that particular service. We’ll need to retrieve the public key from our machine to do so.
Ssh Key Agent Gnome Keyring
Navigate to the .ssh folder and find the file <private-key>.pub. Open this in a text editor. The contents of this file is what you need to copy and paste into the relevant service you’re wanted to add the key to.
Testing the keys
In this example lets assume we’ve added our key to Bitbucket. We can test that the key is correctly set up by running the following command.
If all is well then we should see the logged in as message without needing to enter the passphrase
Using with Git
By now we have our key correctly stored in the SSH agent and we’re allowed to connect to the Bitbucket servers using SSH. However we might still be prompted to enter our passphrase whenever we try to perform a git command that talks to the remote.
The ssh -T command uses the Windows 10 agent so all appears to be correct, but it won’t behave the same in Git. This is due to the fact Git is using it’s own ssh agent, not the Windows 10 agent that we’ve added our keys to.
We need to tell Git to use the Windows SSH agent instead of it’s own. We do this by updating the git config.
Ssh Key Agent Add
Now when we use Git, we won’t be prompted for our passphrase, even after a restart.
Ssh Key Agent Mac
References