In the modern era of hybrid working environments, securing remote connections is paramount. Windows 11, keeping pace with this need, facilitates the integration of OpenSSH server for a secure remote login, utilizing key-based authentication. This post delineates a step-by-step approach to set up OpenSSH server, manage key-based authentication, and handle service operations seamlessly using PowerShell.

Installing OpenSSH Server using PowerShell

1. Launch PowerShell as an Administrator.
2. Execute the following command to install OpenSSH Server:

Add-WindowsFeature -Name OpenSSH.Server

3. Once installed, you can check the installation with:

Get-WindowsFeature -Name OpenSSH.*

Managing SSH Public Key

For User Access:

• Save the public key in C:\Users\<username>\.ssh\authorized_keys.

For Administrator Access:

• Save the public key in C:\ProgramData\ssh\administrators_authorized_keys.

Adding the Key using PowerShell:

Add-Content -Path "C:\Users\<username>\.ssh\authorized_keys" -Value $(Get-Content -Path "<path_to_public_key>")

Managing OpenSSH Service

# check service status
Get-Service -Name sshd
# start service
Start-Service sshd
# stop service
Stop-Service sshd
# restart service
Restart-Service sshd

Understanding SSH-Agent

SSH-Agent is a background program that handles private key operations. It stores your private keys securely, requiring you to unlock them only once, thus easing the authentication process.

Generating SSH Key using PowerShell

ssh-keygen -t ed25519

Follow the on-screen instructions to specify a path and passphrase for your keys.

Adding Key to SSH-Agent

Start-Service ssh-agent ssh-add $env:USERPROFILE\.ssh\id_ed25519

Utilizing the Key for Secure Connection

For using the stored keys in SSH Agent, just run a SSH client as always:

ssh username@server_address

By following the above-mentioned steps, you not only set up a robust OpenSSH server on Windows 11 but also ensure a secure remote connectivity through key-based authentication.

Reference

• Key-based authentication in OpenSSH for Windows
• Get-Service